Tyrosol exhibits negative regulatory effects on LPS response and endotoxemia

Tyrosol, a phenolic compound, was isolated from wine, olive oil and other plant-derived products. In the present study, we first investigated the negative regulatory effects of tyrosol on cytokine production by lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages in vitro, and the results showed that tyrosol reduced tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-1β (IL-1β) secretion. This inspired us to further study the effects of tyrosol in vivo. Tyrosol significantly attenuated TNF-α, IL-1β and IL-6 production in serum from mice challenged with LPS, and consistent with the results in vitro. In the murine model of endotoxemia, mice were treated with tyrosol prior to or after LPS challenge. The results showed that tyrosol significantly increased mice survival. We further investigated signal transduction ways to determine how tyrosol works. The data revealed that tyrosol shocked LPS-induced mitogen activated protein kinases (MAPKs) and nuclear transcription factor-κB (NF-κB) signal transduction pathways in RAW 264.7 macrophages. These observations indicated that tyrosol exerted negative regulatory effects on LPS response in vitro and in vivo through suppressing NF-κB and p38/ERK MAPK signaling pathways.