Small molecule xenobiotics known to be chemotherapeutic and those with chemotherapeutic potential were identified for the database. Freely available and validated online biochemical molecule databases including http://www.chemicalize.org and http://www.chemspider.com were utilized for determinations of 2-dimensional (2-D) molecular structures and ionization state at physiologic pH of ~7.4, analogous to previous methodology for endogenous biomolecules (8). Molecular structure and configurations of xenobiotics were assessed for the type of covalent bonds within the structure, and to the backbone as is the presence or absence of associated molecular charge. The presence of halogenation (0), hydroxylation (0, −1), phosphorylation (−1, −2), carboxylation (−1), carbonylation (C=O), sulfonation (0, +1) and amination (0, +1), whether primary, secondary, tertiary or quaternary (+1) is noted. The amount of polar surface area (psa) is also noted.

The predicted octanol-to-water partition coefficient (poOWPC or OWPC; unitless), the predicted Log Pow, was applied for molecules in neutral or unionized states, and the predicted Log Dow, was applied for molecules in the ionized state. The predicted vdWD (nm) was applied as the measure of estimated molecular size, obtained from the predicted spherical van der Waals volume. The predicted Log OWPC-to-vdWD (nm⁻¹) was determined for the whole molecule, while the predicted incorporating lipophilicity octanol-to-water partition coefficient-to-van der Waals diameter ratio (Log incorpOWPC-to-vdWD; nm⁻¹) was determined for the hydrophobic cores and moieties (hydrophobic moiety/core Log OWPC-to-vdWD; nm⁻¹), and the predicted interactability octanol-to-water partition coefficient-to-van der Waals diameter ratio (Log interactOWPC-to-vdWD; nm⁻¹) was determined for the hydrophilic moieties [or cores] (hydrophobic moiety Log OWPC-to-vdWD; nm⁻¹).

The presence of charge and its distribution over biomolecular space were assessed based on visual inspection of 2-D molecular structures. The classification scheme, as devised with slight modifications, was applied for the characterization of molecular charge over molecular space, as follows:

I. No overall charge: neutral (0), which can be a combination of hydroxylo (OH), carbonylo (C=O), etheroylo (O-CH₃), amidylo (N-C=O), where the presence of peripheral neutral groups in a circumferential or semi-circumferential arrangement around a lipophilic core is designated as Peri or semi-Peri;

II. Sufficient molecular space separation of charge (S) was defined as the presence of focal charges separated in molecular space, in the form of sufficiently separated attractive + or - charge that results in sufficiently separated contributions of cationicity (S 1+ 1+) or of anionicity (S 1- 1-);

III. Insufficient molecular space separation of charge (IS) was defined as the presence of focal charge in molecular space, in the form of insufficiently separated attractive + or - charge that results in insufficiently separated contributions of cationicity (IS 1+ 1+) or of anionicity (IS 1- 1-), where cationoneutral molecular charge is defined as IS 1+ 1-.

Small molecule xenobiotic mode and character of CM cholesterol/phospholipid glycerol-to-fatty acid-ester, CM protein channel or CM receptor interaction were classified, as follows:

I. Pure hydrophiles, defined as xenobiotics without intervening lipophilicity with predicted hydrophilic (−) Log OWPC-to-vdWD ratio (nm⁻¹) at a physiologic pH of 7.4, with non-charged pure hydrophiles being CM aqueous channel pore permeable at vdWDs <0.78 nm and intra-cellularly localizing (0 1- 1+).

II. Hydro-lipophiles, defined as xenobiotics with intervening lipophilicity (Log incorpOWPC-to-vdWD; nm⁻¹) with predicted hydrophilic (−) Log OWPC-to-vdWD ratio (nm⁻¹) at physiologic pH of 7.4, and being CM aqueous channel pore impermeable, with CM non-channel receptor or CM receptor interaction instead, as follows: a) cationic polyhydroxylated/carbonylated/etheroylated [1+ Peri (0)]: channel receptor-mediated CM endocytosis (i.e. doxorubicin); b) cationic-cationic polyhydroxylated/carbonylated/etheroylated [S 1+ 1+ Peri (0)]: channel receptor-mediated CM endocytosis (i.e. vincristine); c) di-cationic-cationic [S IS 1+ 1+ IS 1+ 1+ (0)]: effective cationicity 2+ 2+): non-channel receptor-mediated CM endocytosis (i.e. AMD3100); d) di-carboxylated neutral [S 1- 1- 0 (0)]: non-channel folic acid receptor-mediated CM endocytosis (i.e. methotrexate).

III. Lipohiles, defined as non-charged less lipophilic toxicants with vdWDs <0.78 nm (CM channel pore permeable sub-CM interactors), and as xenobiotics with vdWDs >0.78 nm and overall lipophilicity [(+) Log OWPC-to-vdWD ratio (nm⁻¹)] with sufficient (S) intervening lipophilicity (Log incorpOWPC-to-vdWD; nm⁻¹) in the presence of molecular hydrophilicity (monohydroxylation/monocarbonylated/monoetheroylated/monocarboxylated; polyhydroxylated/polycarbonylated/polyetheroylated; charge) either present isotropically [CM receptor hydrophobic core interactors with vdWDs >0.78 nm (receptor-mediated CM endocytosis)], or present anisotropically (CM cholesterol/phospholipid glycerol-to-fatty acid-ester or CM receptor hydrophobic core interactors with vdWDs >0.78 nm): a) anisotrophic anionic [1- (0)] with linear structure (i.e. chlorambucil), anisotrophic cataniononeutral [IS 1+ 1- (0)] with linear structure (i.e. melphalan), anisotropic polyneutral [0 (0)] with linear structure (i.e. capecitabine), anisotropic polyneutral circular [circ (0)] (i.e. cyclosporine A): CM cholesterol or phospholipid glycerol-to-fatty acid-ester association or disruption; b) isotropic di-neutral [0 (0) 0] with sterol structure: non-channel steroid receptor-mediated pressuromodulation antagonism (i.e. abiraterone); non-channel receptor-mediated pressuromodulation (endogenous sex steroids, i.e. testosterone, estradiol); c) isotropic cationic-neutral [1+ (0) 0] with sterol mimicking structure: non-channel steroid receptor-mediated pressuromodulation antagonism (i.e. hydroxytamoxifen); d) isotrophic cationic semi-polyneutral [1+ semi-Peri (0)] with flexible linear structure: potential for channel receptor-mediated CM endocytosis (i.e. verapamil); e) esotrophic polyneutral [Peri (0)] with compact non-linear structure: non-channel receptor-mediated CM endocytosis (i.e. colchicine); isotrophic polyneutral [Peri (0)] with non-compact non-linear structure: non-channel receptor-mediated CM endocytosis (i.e. etoposide); f) anisotropic di-neutral [0 0 (0)] with part-sterol structure: non-channel receptor P-glycoprotein (P-gp)-mediated pressuromodulation (i.e. artemisinin); g) anisotropic polyneutral [semi-Peri (0)] with sterol structure: non-channel receptor-mediated pressuromodulation (endogenous corticosteroids, i.e. cortisol, aldosterone); h) anisotropic cationic neutral [1+ 0 (0)], isotropic cationic neutral [1+ (0) 0], anisotropic non-cationic di-neutral [0 0 (0)] or isotropic non-cationic di-neutral [0 (0) 0] with non-linear L-to-U-type step-like structure: non-channel receptor-mediated pressuromodulation antagonism (i.e. growth factor and cytokine receptor antagonists).

The poOWPC or OWPC represents the presence of molecular surface area hydrophilicity due to the presence of functional groups of hydrophilic character, and in the case of small molecule xenobiotics of hydrophilic character, the predicted overall Log OWPC is the sole determinant of the overall tendency for interaction with the aqueous phase and represented by the predicted hydrophilic (−) Log OWPC-to-vdWD ratio (nm⁻¹), whereas, in the case of small molecule xenobiotics of lipophilic character with the concomitant presence of hydrophilic moieties sufficiently separated in molecular space (S), the predicted incorporating Log OWPC of the hydrophobic portion is the sole determinant of the specific tendency for interaction with the hydrophobic phase and represented by the predicted lipophilic (+) Log incorpOWPC-to-vdWD ratio (nm⁻¹) to interact or associate with the hydrophobic constituents of the CM, either with the CM bilayer cholesterols and phospholipid fatty acid-esters or with CM protein/receptor hydrophobic cores.

Based on assessment of the 2-D molecular structures of small molecule xenobiotics, those of pure hydrophilic character have a cyclic or linear backbone containing hydrophilic groups, and therefore, pure hydrophilic xenobiotics neither associate with CM phospholipids nor CM proteins and receptors, while those with lower hydrophilicity (−) Log OWPC-to-vdWD ratios (nm⁻¹) can permeate across CM protein channel aqueous pores analogous to permeation across barrier pores, molecular size permitting (8), which, in the case of the least hydrophilic pure hydrophile xenobiotics is ≤0.78 nm (Tables I and II).

Xenobiotics of overall hydrophilic character with incorporating lipophilicity (small molecule hydro-lipophiles) and of overall lipophilic character in the absence or presence of hydrophilic portions/hydrophilic functional groups (small molecule lipophiles) that are larger than vdWD ~0.78 nm do not permeate across CM aqueous channel pores due to a molecular size limitation to permeation, and therefore, instead associate with CM constituents, either with CM phospholipids or with CM phospholipid bilayer bilayer-associated proteins. Based on the structural arrangement of atoms, xenobiotics larger than vdWD ~0.78 nm can be categorized, as follows:

i) Those with non-charged backbone atoms in central linear arrangement in the form of cyclic rings alternating with atoms in chains in the presence or absence of structural anisotropic hydrophilicity (uni-polar hydrophilicity), which results in unstable association with CM associated-protein core hydrophobicity, whereby such xenobiotics associate within CM phospholipid bilayers instead, and pertubation disrupt due to non-biologic interaction spatial displacement of bilayer fatty acid-esters, with the potential for 1ary indirect pressuromodulation at lower concentrations (17) and include cyclosporine A with the capacity for phospholipid interspace widening-disruption upon insertion (Tables III–V).

ii) Those with backbone atoms arranged in non-linear non-compact, or in a step-like configuration of inter-connected cyclic rings, in the presence or absence of alternating with atoms in linear arrangement (L-to-U-type), which results in stable association with CM proteins/CM peptide receptors and non-interaction with CM bilayers (Tables VI–XI).

This category includes the least hydrophilic pure hydrophile small molecule xenobiotics that permeate across CM protein channel aqueous pore nuclear membrane (NM) fenestrations and outer-to-inner mitochondrial membrane (MM) aqueous pores to arrest nuclear DNA transcription and RNA translation function (i.e. Ki67) as well as mitochondrial DNA transcription and RNA translation function, followed by arrest of DNA replication function (Tables I and II, Figs. 1 and 2).

This category of CM, NM and MM pore permeable small molecule xenobiotics include:

i) The DNA and RNA alkylating adductors, nitroso-N-methylurea (EMU) (Log OWPC, −0.55; vdWD, 0.54 nm; Log OWPC-to-vdWD ratio, −1.20 nm⁻¹), temozolomide (TMZ) (Log OWPC, −0.45; vdWD, 0.65 nm; Log OWPC-to-vdWD ratio, −0.70 nm⁻¹) (18) and nitroso-N-ethylurea (ENU) (Log OWPC, −0.22; vdWD, 0.57 nm; Log OWPC-to-vdWD ratio, −0.38 nm⁻¹) (19,20). EMU, TMZ and ENU arrest replicative nuclear function via association with nitrogenous bases, of DNA, and RNA, strand nucleotides with sufficient affinity to alkylate nucleotide nucleosides involved in base pairing hydrogen bonding, which renders alkylated base segments of DNA, and RNA, non-functional; these DNA and RNA alkylating small molecule xenobiotics, but are not P450 cytochrome inducers due to insufficient lipophilicities for size of their hydrophobic moiety (Table I and Fig. 1).

ii) The nucleoside substitutors, decitabine (Log OWPC, −2.35; vdWD, 0.70 nm; Log OWPC-to-vdWD ratio, −3.35 nm⁻¹), gemcitabine (Log OWPC, −1.65; vdWD, 0.72 nm; Log OWPC-to-vdWD ratio, −2.29 nm⁻¹), 5-fluorouracil (5-FU) (Log OWPC, −0.66; vdWD, 0.56 nm; Log OWPC-to-vdWD ratio, −1.18 nm⁻¹) (21) and 3-methyladenine (3-MA) (Log OWPC, −0.31; vdWD, 0.61 nm; Log OWPC-to-vdWD ratio, −0.51 nm⁻¹). Decitabine, gemcitabine and 5-FU arrest replicative function via competitive inhibition with endogenous nitrogenous bases for phosphorylation and/or ribosylation enzyme active sites, by substitution into DNA and RNA strands, thereby rendering substituted nucleotide segments of DNA and RNA non-functional. 3-MA, although a nucleotide substitute for adenosine upon ribosylation phosphorylation, does not interfere with DNA helix base pairing upon substitution due to the exterior presence of the methyl group (CH₃) (as opposed to interior), whereby, the functionality of 3-MA substituted nucleotide segments of DNA is maintained, that which results in increased burst nuclear DNA transcription and competitive activation of mRNA polyadenylation poly(ADP-ribose) polymerase-1 (PARP-1) (22) and in MM oxidative stress with subsequent release of MM apoptosis inducing factor (AIF), AIF binding of X-linked inhibitor of apoptosis factor (XIAF) and generation of free caspases (i.e. caspase-3) with resultant cleavage of transcriptionally active nuclear chromatin (Table II and Fig. 2).

Of such small molecule hydrophilic xenobiotics, those that permeate through CM channel aqueous pores via unrestricted diffusion include those of diameters ranging between 0.54 and 0.65 nm, in the context of overall hydrophilicities for molecular size ranging between −0.38 and −1.20 nm⁻¹. Those that permeate through CM channel aqueous pores with a tendency towards restricted diffusion include those of larger diameters, 0.70 and 0.72 nm, in the context of greater overall hydrophilicities for molecular size of −2.29 and −3.35 nm⁻¹. Such small molecule xenobiotics are permeable across CM protein channel aqueous pores due to the absence of charge, either anionic or cationic, analogous to endogenous molecules such as the nitrogenous bases and nucleosides, which have similar functional groups and fall within a similar range of vdWDs and hydrophilicities for size in the absence of charge, and primarily accumulate in the nucleus, which has NM fenestrations with a functional upper limit of pores of ~9 nm (23), for which the permeability surface area product is greater than that of the MM pores. Although such small molecule xenobiotics primarily accumulate within the nucleoplasm, they can also accumulate within the mitochondrial cytosol, via permeation across outer-to-inner MM protein channel pores [voltage dependent anion channel (VDAC)] (24,25), across which small molecule endogenous hydrophiles of similar vdWDs and hydrophilicities for size, are permeable (26); meanwhile, larger and charged endogenous small molecule hydrophiles more hydrophilic for size, such as ATP (3- and Mg²⁺ → 1-), are not, while smaller and charged endogenous small molecule hydrophiles less hydrophilic for size such as citrate (3- and Ca²⁺ → 1-), succinate (2- → SuccinateH 1- at pH ~7) and HPO₄ (2- → H₂PO₄ 1- at pH ~7) are insignificantly more permeable, as these have permeabilities that fall within the order of magnitude of that of ATP (24), in contrast to chloride (Cl⁻), an anion that is not significantly permeable across CM pores with an anionization-to-atomic diameter ratio (AI-to-AD; nm⁻¹) of 4.90 nm⁻¹, which is 3 orders of magnitude more permeable than ATP with a permeability coefficient of 1.1×10⁻¹² cm³/sec (24), findings that which implicate ‘kiss-and-run’ exocytosis as the basis for ATP release into the cytosol, for secondary permeation into the nucleus.

Small molecule xenobiotics of this category, being of pure hydrophilic character with lesser overall hydrophilicity, are exquisitely permeable across CM aqueous channel pores and into the intra-nuclear compartment, but also into the intra-mitochondrial compartment (27). Thus, such xenobiotic chemotherapies have shown the potential to be uniformly cytotoxic to tumor cells, via effects in both nuclear and mitochondrial compartments in the setting of an actively maintained concentration gradient in vitro, particularly synergistically (28,29). Therefore, in order to demonstrate similar effectiveness in the clinical setting, such small molecule xenobiotics, as well as others discussed herein, must be made to first and foremost selectively accumulate to effective concentrations within tumor tissue, which can only be accomplished upon labile linking to optimally-sized, and designed, nanoparticles within the 8- to 9-nm-size range delivered transvascularly (3–7), to ensure uniform cytotoxicity to all tumor tissue cells and minimal risk for subsequent neoplastic transformation of tumor-associated cells including tumor stem cells.

This category includes small molecule xenobiotics, hydro-lipophiles and lipophiles with hydrophilicity, with vdWDs in the 0.74 to 0.67 nm range, which can permeate across CM, NM and MM aqueous pores with the potential to bind to cytochrome P450s due to the hydrophobicity for size of their hydrophobic moieties, with the potential to arrest nuclear and mitochondrial replication via DNA/RNA alkylation or DNA strand-to-DNA strand crosslinking (Table III and Fig. 3).

This category of CM, NM and MM pore permeable small molecule xenobiotics include:

i) The intra-CM-associated cytochrome P450 hydroxylation-activated (30,31) and intra-MM-associated cytochrome P450 hydroxylation-inactivated (31,32), sub-classified as

a) The intra-CM-associated cytochrome P450 hydroxylation-activated DNA/RNA guanosine guanine alkylator procarbazine (33) (Log OWPC, −1.70; vdWD, 0.74 nm; Log OWPC-to-vdWD ratio, −2.29 nm⁻¹); procarbazine hydrophilic moiety1 (Log OWPC, −0.59; vdWD, 0.51 nm; Log OWPC-to-vdWD ratio, −1.17 nm⁻¹); procarbazine hydrophobic moiety1 (Log OWPC, 2.51; vdWD, 0.57 nm; Log OWPC-to-vdWD ratio, 4.43 nm⁻¹); procarbazine hydrophilic moiety2 (Log OWPC, −1.11; vdWD, 0.43 nm; Log OWPC-to-vdWD ratio, −2.61 nm⁻¹); procarbazine hydrophobic moiety2 (Log OWPC, 1.82; vdWD, 0.48 nm; Log OWPC-to-vdWD ratio, 3.75 nm⁻¹): procarbazine alkylates DNA/RNA guanosine guanines via its CH₃-NH₂-NH₂- terminal hydrophilic moiety1, but without the potential to crosslink (Table III and Fig. 3).

(b) The intra-CM-associated cytochrome P450 hydroxylation-activated DNA strand-to-DNA strand crosslinkers, cyclophosphamide (34) (Log OWPC, 0.10; vdWD, 0.73 nm; Log OWPC-to-vdWD ratio, 0.14 nm⁻¹); cyclophosphamide hydrophilic core (Log OWPC, −1.92; vdWD, 0.59 nm; Log OWPC-to-vdWD ratio, −3.25 nm⁻¹); cyclophosphamide hydrophobic moieties 1 and 2 (Log OWPC, 1.19; vdWD, 0.48 nm; Log OWPC-to-vdWD ratio, 2.49 nm⁻¹) and ifosfamide (Log OWPC, 0.10; vdWD, 0.73 nm; Log OWPC-to-vdWD ratio, 0.14 nm⁻¹); ifosfamide hydrophilic core (Log OWPC, −1.92; vdWD, 0.59 nm; Log OWPC-to-vdWD ratio, −3.25 nm⁻¹); ifosfamide hydrophobic moieties 1 and 2 (Log OWPC, 1.19; vdWD, 0.48 nm; Log OWPC-to-vdWD ratio, 2.49 nm⁻¹). Cyclophosphamide and ifosfamide crosslink DNA strand-to-DNA strand guanine N7s due to the length of their 2 reactive hydrophobic moieties, CH₂-CH₂-CL ×2, rendering G-to-G cross linked segments inseparable, non-functional and prone to strand breaks, and can directly inhibit glutathione reductase (37–41) (Table III and Fig. 3).

ii) The intra-CM-associated cytochrome P450 hydroxylation-inactivated (31,32,35), DNA strand-to-DNA strand crosslinker carmustine (BCNU) (Log OWPC, 0.95; vdWD, 0.67 nm; Log OWPC-to-vdWD ratio, 1.41 nm⁻¹). Carmustine crosslinks DNA strand-to-DNA strand guanine N7s (36) due to the length of its 2 reactive hydrophobic moieties, CH₂-CH₂-Cl ×2, rendering G-to-G cross linked segments inseparable, non-functional and prone to strand breaks, and can directly inhibit glutathione reductase (37–41) (Table III and Fig. 3).

Of such small molecule xenobiotics with intra-structural hydrophobicity, those that are most likely to achieve intra-cellular levels are those that are both of smaller size and relatively less lipophilic, as these can diffuse through CM channel aqueous pores without restriction and partition to a sufficient extent into the aqueous phase, which is the case for procarbazine (Log OWPC-to-vdWD ratio, −2.29 nm⁻¹; vdWD, 0.74 nm) while those most likely to interact with the CM phospholipid bilayer are those that are of larger size as these are restricted to diffusion through CM channel aqueous pores, and importantly, those with greater overall molecular lipophilicity cum larger size, as these have the tendency to associate into the phospholipid bilayer among fatty acid-esters. This is the case of those within the overall lipophilicity range of cyclophosphamide/ifosfamide (Log OWPC-to-vdWD ratio, 0.14 nm⁻¹; vdWD, 0.73 nm) (34,42,43) which are of larger size, and carmustine (Log OWPC-to-vdWD ratio, 1.41 nm⁻¹; vdWD, 0.67 nm) (44), which is more lipophilic (44), for which there is a greater tendency to associate with and perturb CM phospholipids and the potential for a 1ary indirect pressuromodulation-mediated secondary increase in very high molecular weight (MW) protein transcription (17), while such small molecule xenobiotics of lipophilic character may only achieve intra-cellular levels at significant extracellular concentrations (45), which makes the more lipophilic xenobiotics of this category marginal chemoxenobiotics for effective transvascular delivery into solid tumor tissue (3–7) .

This category includes small molecule xenobiotics with hollow isophilic interiors and molecular lipophilicity in the form of the circumferential presence of lipophilic moieties on the exterior, insert in-between CM phospholipids at the phospholipid glycerol-fatty acid ester junctions (46), and include, cyclosporine A (Log OWPC, 3.64; vdWD, 1.31 nm; Log OWPC-to-vdWD ratio, 2.78 nm⁻¹), which has a 5 carbon (5C) alkene tail that predisposes to CM phospholipid glycerol-fatty acid ester association rather than with CM receptor protein hydrophobicity (Table IV and Fig. 4).

Cyclosporine A has been shown to decrease the rate of cell division only in the presence of powerful CM receptor pressuromodulators (47,48), which is due to generation of nuclear transcription-driven burst mitochondrial reactive O₂ species (47,49) secondary to the increased transcription of the intermediate MW proteins (i.e. p53) and BCL depletion, or in the presence of mitochondrial-associated microtubule network disruptors (49), which is due to concomitant mitochondrial anchorage-mediated MM disruption/dissolution toxicity and generation of free caspases (i.e. free caspase-3). At low intra-tumoral concentrations cyclosporine A has more potential to cause 1ary indirect pressuromodulation (perturbomodulation) (17), that would actually cause an increase in the transcription of very high MW proteins such as secretory proteins (i.e. fibronectin, 240 kDa) and nuclear division proteins (Ki67, 359 kDa; separase, 230 kDa) (17). Furthermore, as cyclosporine A is highly serum protein-bound secondary to its overall lipophilicity for size (Log OWPC-to-vdWD ratio, 2.78 nm⁻¹), it is difficult to obtain µM local cyclosporine A intra-tumoral concentrations in standard free drug intravenous chemotherapeutic regimens.

This category includes small molecule xenobiotics, hydro-lipophiles with anisotropic molecular hydrophilicity cum lipophilicity to lipophiles with anisotropic molecular hydrophilicity or absence of, with vdWDs in the 1.18–0.77 nm range (Table V and Fig. 5).

Small molecule xenobiotic hydro-lipophiles with anisotropic molecular hydrophilicity cum lipophilicity include: i) nystatin (Log OWPC, −2.00; vdWD, 1.18 nm; Log OWPC-to-vdWD ratio, −1.70 nm⁻¹); ii) amphotericin B (Log OWPC, −1.30; vdWD, 1.17 nm; Log OWPC-to-vdWD ratio, −1.11 nm⁻¹); iii) filipin (Log OWPC, −0.15; vdWD, 1.00 nm; Log OWPC-to-vdWD ratio, −0.15 nm⁻¹), with their hydrophobic inner crescent having a lipophilicity for size of 8.32 nm⁻¹ (Log OWPC, 6.73; vdWD, 0.81 nm).

Nystatin, amphotericin B and filipin associate with CM bilayer cholesterol with their hydrophobic inner crescent over the exposed outer surface area of CM cholesterol, which is within the range of lipophilicity for the size of the CM bilayer surface cholesterol portion of between 9.25–7.7 nm⁻¹ (Log OWPC, 8.5–7.11; vdWD, 0.92 nm), but do not physically incorporate into CM-associated protein receptor isophilic-to-hydrophobic interiors (cores) due to the presence of anisotropic molecular hydrophilicity cum lipophilicity. Thus, such small molecule xenobiotics remove CM cholesterol via cholesteroloassociation with the more exteriorly protruding cholesterol portion to decrease CM cholesterol concentration, thereby, de-stabilizing the CM sufficiently enough to concomitantly cause CM destabilization-mediated extrusion of CM cholesterol-associated proteins/receptors, and as a result, also have the potential to cause a subsequent 1ary indirect pressuromodulation (perturbomodulation)-mediated secondary increase in very high MW protein transcription (17,50,51) (Table V and Fig. 5).

Small molecule xenobiotic lipophiles with anisotropic molecular hydrophilicity include:

i) Chlorambucil [(Log OWPC, 0.60; vdWD, 0.79 nm; Log OWPC-to-vdWD ratio, 0.76 nm⁻¹); chlorambucil hydrophobic core (Log OWPC, 5.26; vdWD, 0.79 nm; Log OWPC-to-vdWD ratio, 6.75 nm⁻¹)], in the case of small molecule xenobiotic lipophile with anisotropic molecular hydrophilicity, chlorambucil [(Log OWPC, 0.60; vdWD, 0.79 nm; Log OWPC-to-vdWD ratio, 0.76 nm⁻¹); chlorambucil hydrophobic core (Log OWPC, 5.26; vdWD, 0.79 nm; Log OWPC-to-vdWD ratio, 6.75 nm⁻¹)], associates into the CM closely with the CM phospholipid layer-spanning portion of cholesterol that has a lipophilicity of ~7.26 nm⁻¹ which is close to its hydrophobic core lipophilicity of 6.75 nm⁻¹, while transiently stabilizing itself in the layer by concomitantly interacting anisotropically with the layer phospholipid head groups viz a viz its mono-anionic hydrophilic-interacting COO⁻ moiety, to remove cholesterol via cholesteroloassociation secondary to unstable structural association with phospholipid layer fatty acid-ester tails in context of an inability to glyceroloesterify. Therefore, chlorambucil is not an effective intra-cellularly localizing mitochondrial or nuclear DNA/RNA alkylating/bi-functional DNA crosslinking chemoxenobiotic, but instead removes CM cholesterol via cholesteroloassociation with the CM phospholipid layer-spanning interior cholesterol portion to decrease CM cholesterol concentration (52,53) and as a result, has the potential to cause a subsequent 1ary indirect pressuromodulation (perturbomodulation)-mediated secondary increase in very high MW protein transcription (17) (Table V and Fig. 5).

ii) Melphalan [(Log OWPC, 1.00; vdWD, 0.79 nm; Log OWPC-to-vdWD ratio, 1.27 nm⁻¹); melphalan hydrophobic core (Log OWPC, 4.42; vdWD, 0.75 nm; Log OWPC-to-vdWD ratio, 5.86 nm⁻¹)]. In the case of small molecule xenobiotic lipophile with anisotropic molecular hydrophilicity, melphalan [(Log OWPC, 1.00; vdWD, 0.79 nm; Log OWPC-to-vdWD ratio, 1.27 nm⁻¹); melphalan hydrophobic core (Log OWPC, 4.42; vdWD, 0.75 nm; Log OWPC-to-vdWD ratio, 5.86 nm⁻¹)], associates directly into the CM among the CM phospholipid layer fatty acid-ester tails, rather than with the CM phospholipid layer-spanning interior cholesterol portion, along with more stable association within the layer by virtue of the concomitant anisotropic interaction of its cataniononeutral hydrophilic-interacting NH3⁺ COO⁻ moiety with layer phospholipid head groups, that importantly results in its ability to secondarily subsequently trans-displace across CM phospholipid layers and bilayer over time into the intra-cellular compartment. For this reason, melphalan achieves perceptible intra-cellular concentrations, to which specific cytochrome P450s exist (CYP 3A and CYP 27), but without induction. As a result of only a transient cytochrome P450 association in the context of higher affinity association with outer mitochondrial membrane (OMM) bilayer layer fatty acid-ester tails due to a hydrophobic core lipophilicity of 5.86 nm⁻¹, melphalan is not an effective intra-cellularly localizing nuclear DNA/RNA alkylating/bi-functional DNA crosslinking chemoxenobiotic. Therefore, the primary mode of melphalan cellular toxicity is mitochondrial (54–56) and mitochondrially-mediated, via initiation of the mitochondrial cellular apoptosis cascade, beginning at the level of the OMM bilayer (57) upon the displacement of AIF (58,59) from the OMM, as follows: i) disassociation of OMM AIF into the cytosol and binding to XIAF (60) with affinity, thereby disassociating XIAF-bound cytosolic-to-nuclear caspases (caspase-3) (61,62) from bound to free caspase forms, which are pro-membranocytotoxic and pro-nucleochromatotoxic and pro-apoptotic in their free forms; in tandem with ii) association of cytosolic-to-nuclear AIF homolog, BCL (63) with the OMM in place of AIF, thereby, shifting the nuclear BCL bound-p53 equilibrium to free p53 (64–66), being the primary constitutive nuclear transcription factor for PUMA/BIM-like proteins (67,68) and BAX/BID-like proteins (66), whereby, avid binding of BCL by the PUMA and BIM-like proteins, being singular α-helix peptides, leads to further depletion of free BCL (PUMA-BCL and BIM-BCL). The combination of i) and ii) results in mitochondrially-mediated cellular apoptosis (Table V and Fig. 5).

iii) Ketaconazole [(Log OWPC, 4.19; vdWD, 0.94 nm; Log OWPC-to-vdWD ratio, 4.46 nm⁻¹); ketaconazole hydrophobic moiety1 (Log OWPC, 3.30; vdWD, 0.71 nm; Log OWPC-to-vdWD ratio, 4.64 nm⁻¹)]. In the case of small molecule xenobiotic lipophile without anisotropic molecular hydrophilicity, ketaconazole [(Log OWPC, 4.19; vdWD, 0.94 nm; Log OWPC-to-vdWD ratio, 4.46 nm⁻¹); ketaconazole hydrophobic moiety1 (Log OWPC, 3.30; vdWD, 0.71 nm; Log OWPC-to-vdWD ratio, 4.64 nm⁻¹)], associates directly into the CM among the CM phospholipid layer fatty acid-ester tails, but the least stably of those in this category, due to an absence of structural hydrophilic anisotropy. Thus, ketoconazole perturbs the CM bilayer sufficiently enough to secondarily dissociate CM cholesterol from the bilayer, which is the primary mode of ketoconazole cellular toxicity and is attributable to its CM cholesterol removal secondary to perturbation of the CM bilayer with an associated initial decrease in CM and whole cell/intra-cellular pressuromodulation (17,69,70) followed by a secondary increase in very high MW protein transcription due to 1ary indirect pressuromodulation (perturbomodulation) (17), which may result in burst nuclear transcription-associated with mitochondrial oxidative phosphorylation-MM-mediated nuclear and cellular cytotoxicity/apoptosis (17,71) particularly, in the setting of pre-existent concomitant CM receptor pressuromodulation antagnonism such as that of nocodazole (72), a CM receptor pressuromodulation antagonist (Table V and Fig. 5).

iv) Capecitabine [(Log OWPC, 0.75; vdWD, 0.83 nm; Log OWPC-to-vdWD ratio, 0.90 nm⁻¹); capecitabine hydrophobic core (Log OWPC, 1.94; vdWD, 0.61 nm; Log OWPC-to-vdWD ratio, 3.19 nm⁻¹)].

v) Fluconazole [(Log OWPC, 0.56; vdWD, 0.77 nm; Log OWPC-to-vdWD ratio, 0.73 nm⁻¹); fluconazole hydrophobic core (Log OWPC, 1.22; vdWD, 0.76 nm; Log OWPC-to-vdWD ratio, 1.41 nm⁻¹)].

In the case of small molecule xenobiotic lipophiles with anisotropic molecular hydrophilicity with less incorporating lipophilicity, capecitabine [(Log OWPC, 0.75; vdWD, 0.83 nm; Log OWPC-to-vdWD ratio, 0.90 nm⁻¹); capecitabine hydrophobic core (Log OWPC, 1.94; vdWD, 0.61 nm; Log OWPC-to-vdWD ratio, 3.19 nm⁻¹)] and fluconazole [(Log OWPC, 0.56; vdWD, 0.77 nm; Log OWPC-to-vdWD ratio, 0.73 nm⁻¹); fluconazole hydrophobic core (Log OWPC, 1.22; vdWD, 0.76 nm; Log OWPC-to-vdWD ratio, 1.41 nm⁻¹)], both associate directly into the CM among the CM phospholipid layer fatty acid-ester tails, but due to insufficient hydrophobic portion incorporating lipophilicities in the range of between 3.19 and 1.41 nm⁻¹, only temporarily associate into the CM bilayer, to transiently perturb and disorder CM phospholipids, and of the two, fluconazole (vdWD, 0.77 nm) has the potential for CM channel aqueous pore permeation (73), with the potential to also perturb sub-cellular membrane phospholipids including those of the endoGolgi smooth endoplasmic reticulum (SER) with high CM-derived sub-cellular membrane cholesterol phospholipid turnover rates and lower incorporating lipophilicities. In the case of both, capecitabine and fluconazole, the primary mode of cellular toxicity is attributable to perturbation of the CM bilayer with an associated initial decrease in CM and whole cell/intra-cellular pressuromodulation (17,74), in which case, of the two, capecitabine has the greater potential to cause a subsequent 1ary indirect pressuromodulation (perturbomodulation)-mediated secondary increase in very high MW protein transcription (17), that will result in burst nuclear transcription-associated with mitochondrial oxidative phosphorylation-MM-mediated nuclear and cellular cytotoxicity/apoptosis (17,74). In contrast, fluconazole, which also has the potential to cause a subsequent 1ary indirect pressuromodulation (perturbomodulation)-mediated secondary increase in very high MW protein transcription, associated with burst nuclear transcription-associated with mitochondrial oxidative phosphorylation-MM-mediated nuclear and cellular cytotoxicity/apoptosis, does so to a lesser extent in comparison to voriconazole (75), which is structurally similar but more lipophilic than fluconazole and itraconazole (75), which is structurally similar to ketoconazole, as fluconazole also concomitantly decreases sub-cellular membrane compliance (Table V and Fig. 5).

This category includes small molecule xenobiotic hydro-lipophiles with dual cationicity insufficiently separated (IS) in molecular space and backbone lipophilicity, with vdWDs in the 0.70–1.31 nm range. By being cationicity-excluded from permeation across CM protein channel aqueous pores, xenobiotics of this category bind to CM protein receptors, ligand-receptor complexes that endocytose upon xenobiotic binding (Table VI and Fig. 6).

The CM pore impermeable dually-cationic small molecule xenobiotics include:

i) AMD3100 (plerixafor) [(Log OWPC, −5.40; vdWD, 1.00 nm; Log OWPC-to-vdWD ratio, −5.42 nm⁻¹); AMD3100 hydrophobic core (Log OWPC, 3.56; vdWD, 0.81 nm; Log OWPC-to-vdWD ratio, 4.39 nm⁻¹); AMD3100 hydrophilic moiety ×2 (Log OWPC, −6.55; vdWD, 0.76 nm; Log OWPC-to-vdWD ratio, −8.63 nm⁻¹ ×2, +2 cationicity per moiety)];

ii) Paraquat [(Log OWPC, −5.56; vdWD, 0.70 nm; Log OWPC-to-vdWD ratio, −7.98 nm⁻¹); paraquat hydrophobic core (Log OWPC, 2.96; vdWD, 0.70 nm; Log OWPC-to-vdWD ratio, 4.25 nm⁻¹)];

iii) Bleomycin [(Log OWPC, −8.50; vdWD, 1.31 nm; Log OWPC-to-vdWD ratio, −6.50 nm⁻¹); bleomycin hydrophobic core (Log OWPC, 3.14; vdWD, 0.94 nm; Log OWPC-to-vdWD ratio, 3.35 nm⁻¹)].

AMD3100, paraquat and bleomycin associate with CM CXCR4 (76–78), CM paraquat binding protein (PBP) receptor and CM bleomycin binding protein (BBP) (79,80), respectively, and cause CM receptor-mediated CM vesiculo-vacuolization endocytosis and sub-cellular vacuolization-mediated intra-cellular cytotoxicity (81,82), and at least in the case of CM CXCR4 endocytosing xenobiotic, AMD3100, in non-cross talk with lympho-infiltrating cells (T cells) in the milieu, which are necessary for the mounting of an appropriate cytotoxic T cell response (83–85). Furthermore, and importantly, the process of CM receptor-mediated CM vesiculo-vacuolization endocytosis and sub-cellular vacuolization with secondary CM exosome release, is a process that rapidly evolves towards a significant decrease in whole cell compliance in tandem with a significant increase in the transcription of very high MW secretory proteins including the collagens (120–190 kDa) and fibronectins (230 kDa) as well as the nuclear cell division-associated proteins including Ki67 (359 kDa) and separase (230 kDa) (CM receptor-mediated 3ary indirect shift pressuromodulation: receptor endocytic 2+) (17), that are associated with a therapy-related risk for fibrosis (86–88) and mitogenesis division (81,89), respectively, along with the increased risk of metastases due to a concomitant decrease in the transcription of intermediate MW cell surface adhesion proteins (Table VI and Fig. 6).

Due to the risk of endocytosis-mediated 3ary indirect pressuromodulation (17), CM pore impermeable dually-cationic small molecule xenobiotics such as AMD3100, paraquat and bleomycin are tumoropotentiators as monochemotherapies, in a concentration dependent manner (48) (atrial naturetic peptide is an endogenous CM receptor 3ary indirect pressuromodulator (17), which at a higher concentration, likely, induces mitochondrial division), the risk of which can be oviated with synergistic additional direct CM receptor-mediated pressuromodulation as burst nuclear transcription-associated with mitochondrial oxidative phosphorylation-MM-mediated nuclear and cellular cytotoxicity/apoptosis results (89)[dexamethasone is an endogenous CM receptor direct pressuromodulator (17)], as it can also be oviated by synergistic microtubule network inhibition, at the level of the MM VDAC γ-tubulin (Tables VII and IX, Figs. 7 and 9) (90).

This category includes the small molecule xenobiotic hydro-lipophiles with CM channel endocytosing capability due to the presence of sufficient inner incorporating lipophilicity in the context of interacting outer polyhydroxylated carbonylated hydrophilicity in the form of circumferential polyhydroxylated carbonylated hydrophilicity, with vdWDs in the 0.95–1.11 nm range (17). By being hydrophilic and due to the CM protein channel aqueous pore widths, xenobiotics of this category associate with CM protein channel α-helix cum α-helix isophilic aqueous pores to induce CM channel endocytosis of the Ca²⁺ channel (i.e. vincristine) and the Na⁺/K⁺ ATPase (doxorubicin and daunorubicin), and upon CM channel endocytosis disassociation, associate promiscuously with the inner-to-outer MM VDAC, a non-endocytosable circular β-helix with voltage-gateable internal short α-helix-type channel (91) (Table VII and Fig. 7).

The CM channel endocytosing small molecule xenobiotic hydro-lipophiles include: i) vincristine [(Log OWPC, −3.00; vdWD, 1.11 nm; Log OWPC-to-vdWD ratio, −2.69 nm⁻¹); vincristine hydrophobic core (Log OWPC, 5.14; vdWD, 0.96 nm; Log OWPC-to-vdWD ratio, 5.34 nm⁻¹)]; ii) doxorubicin (adriamycin) [(Log OWPC, −0.79; vdWD, 0.95 nm; Log OWPC-to-vdWD ratio, −0.83 nm⁻¹); doxorubicin hydrophobic core (Log OWPC, 4.88; vdWD, 0.77 nm; Log OWPC-to-vdWD ratio, 6.96 nm⁻¹)].

Vincristine and doxorubicin associate into the inter-α-helix isophilic pores of the Ca²⁺ channel (92) and Na⁺/K⁺ ATPase (17,50,51), respectively, to de-stabilize the CM interaction of the multi-inter-α-helix constructs of such trans-membrane proteins, that results in ligand-associated CM protein channel endocytosis (93,94), followed by intra-cellular ligand CM channel disassociation, and then, subsequent promiscuous MM VDAC channel isophilic pore association (95): thus, the primary mechanism of cellular toxicity for vincristine and doxorubicin is at the level of the mitochondria and MM, and due to the concomitant presence of sufficiently separated (SS) 1+ cationicity in the former (vincristine) and exteriorly protruding 1+ cationicity in the latter (doxorubicin), that results in non-association of microtubule γ-tubulin at MM VDAC and non-recruitment of renewed microtubule networks to the MM, mitochondrial anchorage immobility-associated MM disruption/dissolution with liberation of MM AIF and initiation of the mitochondrially-mediated nuclear apoptosis cascade, with the significant potential for inducing cellular apoptosis (96–101), which is due to no significant (in-significant) potential for CM receptor endocytosis-mediated (Pseudo) 3ary indirect pressuromodulation (17) (Table VII and Fig. 7).

The presence of structural cationicity is a pivotal structure distinction between CM channel endocytosing small molecule xenobiotic hydro-lipophiles such as vincristine and doxorubicin that induce non-association of microtubule γ-tubulin at MM VDAC and result in CM mitochondrial anchorage non-mobility-mediated MM disruption/mitochondrial-mediated apoptosis, in contrast to those that do not but with instead have mitogenic potential, which is the case for ouabain (102), a non-cationic circumferentially carbonylated/hydroxylated hydro-lipophile endocytoser of the Na⁺/K⁺ ATPase, with potential to cause epithelilal-to-mesenchymal transformation (EMT) as well as tumoropropagation via CM receptor endocytosis-mediated (Pseudo) 3ary indirect pressuromodulation (17).

The xenobiotics of this category induce endocytosis of their respective channels, the Ca²⁺ channel (123 kDa N/P/Q α subunit MW) (92) (vincristine > verapamil) and the Na⁺/K⁺ ATPase channel (112 kDa α subunit MW) (103) (ouabain, momensin, doxorubicin and daunorubicin), which are present on the CM in juxtaposition to one another and to P-gp (non-glycosylated MW 140 kDa) (104), whereby, ligand-mediated Ca²⁺ channel-endocytosis of associated CM results in concomitant endocytosis of P-gp (105), that decreases immediate P-gp CM expression. Thus, P-gp overexpression and associated multi-drug resistance emerges, secondarily, in surviving tumor cells with lower compliance set points than before therapy due to the increased transcription of higher MW proteins such as P-gp (11), in which case, intra-cellularly accumulating drug fraction is extruded by its ability to interact with intra-CM P-gp α-helixes viz a viz hydro-lipophile incorporating lipophilicity, and induce, α-helix apposition pump functionality (104).

Furthermore, true CM P-gp small molecule ligands that associate with the P-gp extracellular loop-α-helix are few and far between, and include artemsinin (106), which functions as a P-gp inhibitor but also as a pressuromodulator, thus, P-gp inducer, as do ones with hollow interiors including QZ59-RRR and QZ59-SSS (104); whereas, small molecule ligands with less polyneutral exterior hydrophilicity than vincristine, include quinidine (105), a competitive antagonist of vincristine at the Ca²⁺ channel, with the ability to obstruct the channel, but without the ability to endocytose it, whereby, it functions as a Ca²⁺ channel pressuromodulator and inducer, and thus, indirectly as an inducer of Na⁺/K⁺ ATPase and P-gp, all present in close CM pressuromodulating proximity.

This category includes the small molecule xenobiotic hydro-lipophiles with CM folic acid receptor (FAR) endocytosing capability due to the presence of incorporating lipophilicity in the context of anisotropic interacting outer dual carboxylation hydrophilicity, with vdWDs at 0.89 nm. The xenobiotics of this category associate into the FAR hydrophobic core while concomitantly associating with the hydrophilic exterior FAR cationic (+) R groups via the carboxyl (COO⁻) groups (107), which results in a contraction-pull down of the loose non-aligned multi-α-helix FAR towards the CM. This results in the endocytosis of the ligand-FAR complex at a much faster rate than that induced by endogenous ligand folic acid (folate), which has a lower kDa than that of the competitive pro-endocytic xenobiotics of this category (108) (Table VIII and Fig. 8).

The CM FAR endocytosing small molecule xenobiotic hydro-lipophiles include: i) methotrexate [(Log OWPC, −6.60; vdWD, 0.89 nm; Log OWPC-to-vdWD ratio, −7.40 nm⁻¹); methotrexate hydrophobic core (Log OWPC, 1.23; vdWD, 0.77 nm; Log OWPC-to-vdWD ratio, 1.60 nm⁻¹)]; ii) raltitrexed (Tomudex) [(Log OWPC, −4.40; vdWD, 0.89 nm; Log OWPC-to-vdWD ratio, −4.93 nm⁻¹); raltitrexed hydrophobic core (Log OWPC, 3.67; vdWD, 0.78 nm; Log OWPC-to-vdWD ratio, 4.70 nm⁻¹)].

Both methotrexate and raltitrexed endocytose the ligand-FAR complex, initially at the level of the CM, the CM FAR, and upon CM FAR endocytosis followed by intra-cellular disassociation, re-associate/bind to the sub-cellular membrane FARs, the MM FAR and the rough endoplasmic reticulum (RER) FAR inducing their endocytosis. This cumulates in increased sub-cellular vesiculization-mediated generation of pro-oxidant reactive oxygen species (109,110), and in case of the mitochondria, vesiculization-mediated loss of MM electromotive potential (109,111–113). Therefore, the mechanism for anti-folate chemoxenobiotic-mediated cellular cytotoxicity is FAR endocytosis-driven sub-cellular pro-oxidant oxidative stress (114–117), particularly mitochondrial, whereby there is only limited potential for CM receptor endocytosis-mediated (Pseudo) 3ary indirect pressuromodulation (110,118) (Table VIII and Fig. 8).

This category includes the small molecule xenobiotic lipophiles with CM receptor endocytosing capability, with vdWDs in the 0.87–1.01 nm range. Due the presence of inner incorporating lipophilicity in the context of outer circumferential hydrophilicity in the form of hydroxylation/carbonylation/etheroylation/dual carboxylation, the xenobiotics of this category associate into multiple α-helix-type protein receptor hydrophobic cores to destabilize the protein receptor construct sufficiently enough to cause ligand-associated CM receptor endocytosis followed by intra-cellular disassociation. Re-association with affinity to soluble β-tubulin inhibits microtubule de-/re-polymerization function and results in mitochondrial anchorage resultant MM disruption/mitochondrial dissolution (119,120). For this reason, small molecule xenobiotics in this category have no significant (in-significant) risk for secondary CM receptor endocytosis-mediated (Pseudo) 3ary indirect pressuromodulation resultant increase in nuclear transcription of very high MW proteins (17) (Table IX and Fig. 9).

The small molecule xenobiotic lipophiles with CM receptor endocytosing capability include: i) etoposide (VP16) [(Log OWPC, 1.16; vdWD, 0.97 nm; Log OWPC-to-vdWD ratio, 1.20 nm⁻¹); etoposide hydrophobic core (Log OWPC, 3.88; vdWD, 0.76 nm; Log OWPC-to-vdWD ratio, 5.09 nm⁻¹)]; ii) teniposide (VM26) [(Log OWPC, 2.78; vdWD, 1.00 nm; Log OWPC-to-vdWD ratio, 2.79 nm⁻¹); teniposide hydrophobic core (Log OWPC, 3.88; vdWD, 0.76 nm; Log OWPC-to-vdWD ratio, 5.09 nm⁻¹)]; iii) colchicine [(Log OWPC, 1.42; vdWD, 0.87 nm; Log OWPC-to-vdWD ratio, 1.62 nm⁻¹); colchicine hydrophobic core (Log OWPC, 4.98; vdWD, 0.72 nm; Log OWPC-to-vdWD ratio, 6.88 nm⁻¹)]; iv) paclitaxel [(Log OWPC, 3.54; vdWD, 1.12 nm; Log OWPC-to-vdWD ratio, 3.16 nm⁻¹); paclitaxel hydrophobic core (Log OWPC, 5.65; vdWD, 0.87 nm; Log OWPC-to-vdWD ratio, 6.46 nm⁻¹)]; v) ixabepilone [(Log OWPC, 3.39; vdWD, 0.97 nm; Log OWPC-to-vdWD ratio, 3.51 nm⁻¹); ixabepilone hydrophobic core (Log OWPC, 6.21; vdWD, 0.90 nm; Log OWPC-to-vdWD ratio, 6.91 nm⁻¹)]; vi) (+/-) spiro-oxanthromicin A [(Log OWPC, 2.40; vdWD, 1.01 nm; Log OWPC-to-vdWD ratio, 2.38 nm⁻¹); (+/-) orthogonal spiro-oxanthromicin A hydrophobic cores (Log OWPC, 5.47; vdWD, 0.74 nm Log OWPC-to-vdWD ratio, 7.39 nm⁻¹/core)].

For i through vi, CM receptor de-stabilization-mediated endocytosis and intra-cellular re-association with soluble β-tubulin results in inhibition of microtubule polymerization de-/re-polymerization causing sub-cellular organelle anchorage non-motility, and generates intra-cellular reactive pro-oxidant species concomitant with mitochondrial anchorage immobility-associated MM disruption/dissolution with liberation of MM AIF and initiation of the mitochondrial-mediated nuclear apoptosis cascade (120–131), which have the significant potential for inducing cellular apoptosis, particularly those in incorporating lipophilicities in the intermediate range (Table IX and Fig. 9).

vii) Tacrolimus (FK506) [)Log OWPC, 5.59; vdWD, 1.13 nm; Log OWPC-to-vdWD ratio, 4.94 nm⁻¹); tacrolimus hydrophobic core (Log OWPC, 9.07; vdWD, 0.99 nm; Log OWPC-to-vdWD ratio, 9.14 nm⁻¹)] and everolimus (132), with greater incorporating lipophilicity (9.14 nm⁻¹) associate with the FKBP12/inter-domain (I–II/III) of FKBP52 (133).

In contrast to i) through vi) of this category, the CM chemokine receptor endocytosing immunosuppressives, tacrolimus, in the case of xenobiotics such as tacrolimus, xenobiotic-induced disassociation of the FKBP52 domain III from α/β-tubulin results in a slight propensity for inhibition of tubulin de-polymerization (propensity for tubulin polymerization) (133), while the concomitant disassociation of the PUMA-like FKBP52 domain IV from BCL results in generation of cytosolic free BCL, which overcomes mitochondrial anchorage immobility-associated MM disruption due to the MM stabilizing effect of BCL (134–137) (Table IX and Fig. 9).

The CM receptor endocytosing small molecule xenobiotic lipophiles of this category have significant potential to be tumorocytotoxic, particularly in synergism with other tumorocytotoxic chemoxenobiotics [nuclear (i.e. 5-FU) (138) and mitochondrial (i.e. doxorubicin) (9,138)]. The primary limitation to efficacy when administered as a part of current free drug chemotherapy regimens is secondary to a high level of serum protein-binding due to overall lipophilicity for size (Log OWPC-to-vdWD ratio range, 1.2–3.51 nm⁻¹), which makes it is difficult to obtain micromolar local intra-tumoral concentrations at which they are most effective. Therefore, the overall efficacy of such tumorocytotoxic small molecule xenobiotic lipophiles can be significantly improved via the EPR effect, as has shown to be the case for abraxane, a semi-polydisperse paclitaxel (non-covalent) albumin-microaggregate nanoparticulate (H_D ~120 nm) (139,140), which proteolytically degrades into smaller globular paclitaxel (non-covalent) albumin (H_D ~7–10 nm) to enter the tumor interstitium, that results in greater local intra-tumoral concentration of improved efficacy of such small molecule chemoxenobiotics (3–7).

This category includes the small molecule xenobiotic lipophiles with CM receptor pressuromodulation antagonism/partial antagonism capability, with vdWDs in the 0.86–0.89 nm range. Due the presence of inner incorporating lipophilicity commensurate with that of the sex steroid receptor hydrophobic cores, the xenobiotics of this category bind to sex steroid receptor complexes with less affinity than endogenous sex steroids, and thus, function as short-duration pressuromodulators, in contrast to the endogenous sex steroids, which are prolonged duration CM receptor pressuromodulators (17) (Table X and Fig. 10).

The small molecule xenobiotic lipophiles with CM receptor pressuromodulation antagonism/partial antagonism capability include:

i) Hydroxytamoxifen (afimoxitene) [(Log OWPC, 3.00; vdWD, 0.89 nm; Log OWPC-to-vdWD ratio, 3.37 nm⁻¹); hydroxytamoxifen hydrophobic core (Log OWPC, 5.36; vdWD, 0.75 nm; Log OWPC-to-vdWD ratio, 7.14 nm⁻¹)], with hydrophobic core lipophilicity similar to that of the estradiol and estriol sterol backbone (Log OWPC, 5.28; vdWD, 0.78 nm) at 6.81 nm⁻¹ (17), which has a bulky unstable exterior extracellularly-interacting hydrophilicity and insufficient for prolonged duration binding to the estrogen receptor (ER) complex (141).

ii) Abiraterone [(Log OWPC, 3.81; vdWD, 0.86 nm; Log OWPC-to-vdWD ratio, 4.41 nm⁻¹); abiraterone hydrophobic core (Log OWPC, 5.42; vdWD, 0.80 nm; Log OWPC-to-vdWD ratio, 6.74 nm⁻¹)], with hydrophobic core lipophilicity similar to that of the dihydrotestosterone (DHT) sterol backbone (Log OWPC, 5.82; vdWD, 0.81 nm) at 7.18 nm⁻¹ (17), which has lesser exterior extracellularly interacting hydrophilicity and insufficient for prolonged duration binding at the DHT receptor complex (142).

The sex steroid competitive antagonist chemoxenobiotics are pressuromodulation/partial pressuromodulation antagonists of the respective α-helix-based sex steroid receptor types due to the non-binding of the endogenous small molecule sex steroid pressuromodulators, but their competitive binding to the respective sex steroid hormone receptor complexes still results in impartial pressuromodulation of the α-helix-based small molecule sex steroid receptor complex. Thus, the overall effect of CM receptor pressuromodulation antagonism at the sex steroid hormone receptor is sufficient enough to decrease the rate of mitogenesis and cell division by decreasing the rate of protein transcription of very high MW nuclear division proteins, Ki67 (359 kDa) and separase (230 kDa). As such, the sex steroid hormone CM receptor pressuromodulation/partial pressuromodulation antagonists have the potential for temporizing solid tumor growth/progression (143,144), as do upstream releasing hormone inhibitors of luteinising hormone (LH) action on the gonadal sex steroid axis (145), however, in the physiologic state are not tumorocidal (146–148), which is due to the presence of a plethora of CM receptor pressuromodulators in the solid tumor milieu, paracrine and autocrine, and therefore, an abundance of tumor CM receptor-mediated pressuromodulation escape mechanisms, there is a high risk of local and/or metastatic re-occurence upon cessation of sex steroid CM receptor pressuromodulation/partial pressuromodulation antagonist-based chemotherapy (Table X and Fig. 10).

This category includes the small molecule xenobiotic lipophiles and hydro-lipophiles with CM receptor pressuromodulation antagonism/partial antagonism cum pressuromodulation extracellulomodulation and concomitant receptor kinase inhibition capability, with vdWDs in the 0.82–0.97 nm range. Due to L-to-U-type step-like backbone structural configurations, in context of the presence of inner incorporating lipophilicity commensurate with that of the growth factor and cytokine CM receptor hydrophobic cores, the xenobiotics of this category bind to growth factor and cytokine CM receptor subunits with affinity. In the case of the endogenous growth factors and cytokines [i.e. EGF, ALK, SDF-1 and asialoglycoprotein receptor (AGR) ligand] that bind to α-helix-rich receptors (17), the presence of the CM pressuromodulator antagonist/partial antagonist results in non-binding of the endogenous growth factor or cytokine, which results in partial ligand antagonist-mediated CM receptor pressuromodulation; while, in the case of the endogenous growth factors and cytokines (i.e. PDGF, GM-CSF and TRAIL) that bind to β-helix-based subunit receptors (17), the concomitant presence of the CM pressuromodulator antagonist/partial antagonist results in less effective, lower affinity binding of the endogenous growth factor or cytokine, which results in partial endogenous growth factor or cytokine-mediated CM receptor pressuromodulation (Table XI and Fig. 11).

The small molecule xenobiotic lipophiles or hydro-lipophiles that bind to α-helix-rich receptors in lieu of endogenous growth factors or cytokines as direct CM receptor partial pressuromodulation antagonists (17) include:

i) The EGF receptor antagonists (149–156), gefitinib (Iressa) [(Log OWPC, 3.75; vdWD, 0.89 nm; Log OWPC-to-vdWD ratio, 4.21 nm⁻¹); gefitinib hydrophobic core (Log OWPC, 4.21; vdWD, 0.74 nm; Log OWPC-to-vdWD ratio, 5.71 nm⁻¹)], erlotinib (Tarceva) [(Log OWPC, 3.20; vdWD, 0.87 nm; Log OWPC-to-vdWD ratio, 3.67 nm⁻¹); erlotinib hydrophobic core (Log OWPC, 3.61; vdWD, 0.74 nm; Log OWPC-to-vdWD ratio, 4.88 nm⁻¹)], lapatinib [(Log OWPC, 2.12; vdWD, 0.96 nm; Log OWPC-to-vdWD ratio, 2.20 nm⁻¹); lapatinib hydrophobic core (Log OWPC, 6.68; vdWD, 0.89 nm; Log OWPC-to-vdWD ratio, 7.51 nm⁻¹)] and afatinib [(Log OWPC, 1.11; vdWD, 0.91 nm; Log OWPC-to-vdWD ratio, 1.22 nm⁻¹); afatinib hydrophobic core (Log OWPC, 4.21; vdWD, 0.74 nm; Log OWPC-to-vdWD ratio, 5.71 nm⁻¹)].

ii) The ALK receptor antagonists (157–160), ceritinib [(Log OWPC, 3.40; vdWD, 0.97 nm; Log OWPC-to-vdWD ratio, 3.67 nm⁻¹); ceritinib hydrophobic core (Log OWPC, 7.16; vdWD, 0.89 nm; Log OWPC-to-vdWD ratio, 8.02 nm⁻¹)] and crizotinib [(Log OWPC, 1.00; vdWD, 0.88 nm; Log OWPC-to-vdWD ratio, 1.13 nm⁻¹); crizotinib hydrophobic core (Log OWPC, 5.96; vdWD, 0.88 nm; Log OWPC-to-vdWD ratio, 6.88 nm⁻¹)].

iii) The CXCR receptor antagonist (76,77,161,162), AMD070 [Log OWPC, −0.14; vdWD: 0.85 nm; Log OWPC-to-vdWD ratio, −0.16 nm⁻¹; AMD070 hydrophobic core (Log OWPC, 4.33; vdWD, 0.84 nm; Log OWPC-to-vdWD ratio, 5.13 nm⁻¹)].

iv) AGR antagonist (163–169), staurosporine [(Log OWPC, 1.20; vdWD, 0.91 nm; Log OWPC-to-vdWD ratio, 1.32 nm⁻¹); staurosporine hydrophobic core (Log OWPC, 5.72; vdWD, 0.81 nm; Log OWPC-to-vdWD ratio, 7.08 nm⁻¹)].

The EGF receptor antagonists, ALK receptor antagonists and CXCR receptor antagonists cause for a decrease the rate of protein transcription of synthesizable proteins by CM receptor partial pressuromodulation antagonism of tumor CM receptors. The decrease in the transcription of the very high MW nuclear cell division proteins, Ki67 (359 kDa) and separase (230 kDa) (170) results in decreased mitogenesis and cell division, while the decrease in the transcription of the lower MW protein forms including VEGF (20 kDa) necessary for autocrine angiogenesis (154,171), and importantly, BCL (26 kDa) necessary for maintenance of MM integrity in tumor cells (BCL-dependent) (59), results in increased mitochondria-mediated apoptosis, particularly in p53-deficient tumor cells (172–174) (Table XI and Fig. 11).

The small molecule xenobiotic lipophiles that bind to multi-subunit polymeric β-helix β-helix-based receptors to decrease the binding affinity of endogenous growth factors or cytokines and function as direct CM receptor pressuromodulation/partial pressuromodulation antagonists (17) include:

i) The PDGF receptor antagonist (175–177), imatinib [Gleevac CGP 57148) [(Log OWPC, 1.50; vdWD, 0.94 nm; Log OWPC-to-vdWD ratio, 1.59 nm⁻¹); imatinib hydrophobic core (Log OWPC, 5.21; vdWD, 0.87 nm; Log OWPC-to-vdWD ratio, 6.00 nm⁻¹)].

ii) The GM-CSF receptor antagonist (178,179), MK-2206 [(Log OWPC, 1.80; vdWD, 0.87 nm; Log OWPC-to-vdWD ratio, 2.07 nm⁻¹); MK-2206 hydrophobic core (Log OWPC, 6.71; vdWD, 0.82 nm; Log OWPC-to-vdWD ratio, 8.14 nm⁻¹)]:

The PDGF receptor antagonist(s) and GM-CSF receptor antagonist(s), imatinib and MK-2206, still permit concomitant receptor subunit binding of the respective endogenous growth factors, PDGF and GM-CSF, which are prolonged duration endogenous direct CM receptor pressuromodulators of multi-subunit polymeric β-helix-based receptors, but decrease the potency of the pressuromodulation effect by causing a decrease in the affinity of the receptors for endogenous PDGF and GM-CSF, respectively. Therefore, a decrease the rate of protein transcription of synthesizable proteins, results in decreased mitogenesis and cell division due to a decrease in the transcription of the very high MW nuclear cell division proteins, Ki67 (359 kDa) and separase (230 kDa) (180), and increases the likelihood of mitochondria-mediated apoptosis in more BCL-dependent tumor cells (181) due to a decrease in the transcription of BCL (26 kDa) (181) (Table XI and Fig. 11).

The small molecule xenobiotic lipophiles or hydro-lipophiles that bind to multi-subunit polymeric β-helix-based receptors to decrease the binding affinity of endogenous growth factors or cytokines and function as 2ary indirect quad receptor internal pseudo-cationomodulator (SS 1+) pressuromodulation/partial pressuromodulation antagonists (17) include.

The TRAIL receptor antagonists (182–186), a) hydroxycamptothecin [(Log OWPC, 0.92; vdWD, 0.82 nm; Log OWPC-to-vdWD ratio, 1.12 nm⁻¹); hydroxycamptothecin hydrophobic core (Log OWPC, 4.19; vdWD, 0.80 nm; Log OWPC-to-vdWD ratio, 5.24 nm⁻¹)]; b) topotecan [(Log OWPC, −2.10; vdWD, 0.88 nm; Log OWPC-to-vdWD ratio, −2.39 nm⁻¹); topotecan hydrophobic core (Log OWPC, 4.71; vdWD, 0.82 nm; Log OWPC-to-vdWD ratio, 5.77 nm⁻¹)].

The TRAIL receptor antagonists, hydroxycamptothecin and topotecan, still permit the concomitant binding of the endogenous TRAIL, but decreases the potency of the pressuromodulation effect by causing for a decrease in the affinity of TRAIL R2 for endogenous TRAIL, which is an extremely portent prolonged duration 2ary indirect pressuromodulator multi-subunit poly-meric β-helix-based receptors (187–191). As such, hydroxycamptothecin and topotecan-mediated CM receptor pressuromodulation antagonism of TRAIL results in TRAIL pressuromodulation-mediated TRAIL R2 chromatin transcription and in auto-induction of TRAIL R2 at the CM (192) as well as in that of the lower-to-higher MW proteins (i.e. VEGF, 20 kDa; p21; p53; topoisomerase I, 90 kDa; HIF1-α, 93 kDa; P-gp, 140 kDa; topoisomerase II-α, 174 kDa) (186,193), but not of the highest MW nuclear division-associated proteins (Ki67, 359 kDa; separase, 230 kDa), in which case, the increased transcription of intermediate MW protein, p53 (53 kDa) (184,186), results in the depletion of free BCL (p53-BCL) and in mitochondrial-mediated oxidative stress sufficient to induce apoptosis (182,183) that maybe associated with a secondary decrease in mitogenesis and cell division (182) in synergism with additional CM receptor pressuromodulation antagonism (185) (Table XI and Fig. 11).

The CM receptor growth factor or cytokine pressuromodulation/partial pressuromodulation antagonists, including the direct CM pressuromodulation/partial pressuromodulation antagonists of the hepatocyte growth factor (HGF)/scatter factor (SF) receptor family (194–197), have the potential for halting solid tumor growth/progression during the treatment phase (150). However, due to significant concentrations of growth factor and cytokine CM receptor pressuromodulators in the solid tumor milieu, paracrine and autocrine, in context of the significant redundancy of growth factor and cytokine receptors on tumor CMs for CM receptor-mediated pressuromodulation, are not tumorocidal in the physiologic state, as evidenced by the high incidence of local solid tumor re-occurence upon cessation of treatment phase, due to the remaining presence of resistant tumor cells overexpressing mutated receptor subtypes (198) and the EMT transformation of epithelium of tumorgenic potential (199), for example, in the case of weak CM pressuromodulator antagonists such as gefitinib (152,198) with greater binding affinities for their receptors.

CM receptor growth factor or cytokine pressuromodulation/partial pressuromodulation antagonism-based synergistic approaches with the potential for tumorocidal tumorocytotoxicity include those employing ones such as staurosporine (59,164,167,168), imatinib (200), MK-2206 (201) and topotecan (186), particularly, upon effective transvascular delivery into solid tumors across VEGF-derived and maintained diaphragm fenestrated tumor blood capillaries (3–8).

In conclusion, based on these observations herein, on the modes, levels and character of interactions of xenobiotics and chemoxenobiotics with cells, analyzed in terms of the predicted conserved biophysical properties, insight has been gained into the specific mechanisms by which chemoxenobiotics enter cells and the organelles with which they interact to induce cytotoxcity. This knowledge is applicable towards improving the effectiveness of combination small chemotherapy regimens in present clinical use, for the treatment of solid and hematopoietic malignancies, including the order in which chemoxenobiotics are administered in combination treatment regimens, in temporal proximity. It is anticipated that by the application of this study's findings on the modes and character of cellular interactions, existing combination chemotherapy regimens can be designed to be more efficacious, and furthermore, that by the incorporation of this knowledge into the algorithms for the design of personalized cancer treatments, the predictive accuracy of such algorithms can be further optimized.

The observations of this study also underscore the importance of focusing attention on specific CM receptors that mediate the cellular interactions of the various classes of molecular size-restricted chemoxenobiotics, particularly that of pro-endocytic xenobiotics, as the proteomic profiling of the density of these protein receptors across tumor types and grades will result in most sensitive personalized cancer treatments employing existing chemotherapeutic regimens. This being stated, for the curative treatment of solid malignancies, small molecule chemoxenobiotics must be made to selectively accumulate within the micromolar concentrations in the tumor milieu, where they must remain for prolonged duration in order for uniform tumorocidal cytotoxcity to tumor and tumor-associated cells, which will require the further translational development of novel chemotherapeutic regimens employing optimally-sized and -designed biocompatible imageable dendrimer-based nanoparticles bearing labilely attached small molecule chemoxenobiotics.