Anti-inflammatory effect of tribulusamide D isolated from Tribulus terrestris in lipopolysaccharide-stimulated RAW264.7 macrophages

Tribulus terrestris (T. terrestris) has been used as a traditional medicine for the treatment of a variety of diseases, including inflammation, edema and hypertension. The aqueous and ethanol extracts of T. terrestris contain alkaloids, flavonoids, tannins, quinines and phenolic compounds. Tribulusamide D is a compound that has been isolated from the ethanol extract of T. terrestris. The present study investigated the anti‑inflammatory effect of tribulusamide D on lipopolysaccharide (LPS)‑stimulated RAW 264.7 macrophages. Tribulusamide D inhibited the production of LPS‑induced nitric oxide and prostaglandin E2, by reducing the expression of inducible nitric oxide synthase and cyclooxygenase‑2 expression, respectively. The expression of these genes associated with inflammation was determined using reverse transcription‑polymerase chain reaction and western blot analysis. Furthermore, tribulusamide D reduced the expression of LPS‑induced inflammatory cytokines, including interleukin (IL)‑6, IL‑10 and tumor necrosis factor‑α. They were quantified using an enzyme‑linked immunosorbent assay. In addition, the present study confirmed that the inhibitory effects of tribulusamide D on the inflammatory response were mediated through inactivation of mitogen‑activated protein kinase p38 and inhibition of nuclear localization of nuclear factor‑B, which were also determined by western blot analysis. To the best of our knowledge, the current study is the first to demonstrate that tribulusamide D exerts anti‑inflammatory activity by altering the expression of inflammatory mediators and cytokines, indicating that tribulusamide D could be developed as a potential therapeutic agent for the treatment of inflammatory disorders.