Hydroxytyrosol inhibits pro-inflammatory cytokines, iNOS, and COX-2 expression in human monocytic cells.

Hydroxytyrosol (HT), isolated from extra-virgin olive oil, possesses a marked antioxidant activity and is a good radical scavenger. In this study, our aim was to examine the anti-inflammatory mechanism of HT through measuring the inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) expression, TNF-alpha formation, and nitric oxide (NO) release in lipopolysaccharide (LPS)-induced human monocytic (THP-1) cells. Results showed that HT remarkably suppressed the LPS (1 microg/ml) induction of NO release. It also significantly attenuated the LPS-induced transcription of TNF-alpha, iNOS, and COX-2 in a dose-dependent manner. Furthermore, it was also found that HT in a concentration-dependent manner inhibited the expression of iNOS and COX-2 in THP-1 cells treated with 1 microg/ml LPS using Western Blot. Taken together, these results suggest that HT exerts anti-inflammatory effects probably through the suppression of COX-2 and iNOS expression.