N‑trans‑ρ‑caffeoyl tyramine isolated from Tribulus terrestris exerts anti‑inflammatory effects in lipopolysaccharide‑stimulated RAW 264.7 cells.

Inflammation is induced by the expression of cyclooxygenase‑2 (COX‑2), which is an important mediator of chronic inflammatory diseases, such as rheumatoid arthritis, asthma and inflammatory bowel disease. Tribulus terrestris (T. terrestris) is known to have a beneficial effect on inflammatory diseases. In this study, we investigated the effects of N‑trans‑ρ‑caffeoyl tyramine (CT) isolated from T. terrestris on the production of nitric oxide (NO), and the expression of pro‑inflammatory cytokines and COX‑2 in lipopolysaccharide (LPS)‑stimulated RAW 264.7 cells. We also aimed to elucidate the molecular mechanisms involved. We found that the ethanolic extract of T. terrestris (EETT) and CT inhibited the production of NO, tumor necrosis factor‑α (TNF‑α), interleukin (IL)‑6 and IL‑10 in the LPS‑stimulated RAW 264.7 cells in a dose‑dependent manner. They were determined by reverse transcription-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA). In addition, CT markedly suppressed the expression of COX‑2 and the production of prostaglandin E2 (PGE2) in response to LPS stimulation. Furthermore, CT markedly decreased p‑c‑Jun N‑terminal kinase (p‑JNK) protein expression in LPS‑stimulated RAW 264.7 cells. COX-2 and p-JNK were measured by western blot analysis. Taken together, these findings indicate that CT isolated from T. terrestris is a novel and potent modulator of inflammatory responses. Thus, it may prove benefiical to further evaluate CT as a possible treatment for chronic inflammatory diseases.