Pistacia lentiscus var. Chia of the Anacardiaceae family is grown almost exclusively in the southern part of Chios island, a Greek island in the Aegean. Chios mastic gum (CMG) and essential oil are natural antimicrobial and antioxidant agents that have found extensive uses in Mediterranean and Middle Eastern countries, both as a dietary supplement and as a herbal remedy since ancient years. The CMG's cardioprotective effect, via its antioxidant capacity is known, however data on its anti-inflammatory effect on endothelium are scarce. The neutral fraction of CMG (CMGNF) consists of several triterpenic compounds, among which the phytosterol tirucallol. In this study, we examined the hypothesis that CMGNF and tirucallol exert anti-inflammatory effects and could inhibit the expression of adhesion molecules (VCAM-1 and ICAM-1) in Human Aortic Endothelial cells (HAECs). CMGNF (25–200µg/ml) and tirucallol (1–100µM) were incubated with HAECs for 18h and then the cells were stimulated for 6 further hours with TNF-α (1ng/ml). α-Tocopherol was used as positive control. After incubation the cells were fixed and finally the expression of VCAM-1 and ICAM-1 was quantified using a microplate ELISA reader. CMGNF (100, 200µg/ml) caused a significant decrease in VCAM-1 and ICAM-1 expression (p<0.001, p<0.01), compared to TNF-α-treated HAECs. Tirucallol (10, 100µM), also inhibited significantly VCAM-1 and ICAM-1 expression (p<0.001, p<0.01). Concluding, CMGNF has a noticeable anti-inflammatory potential that can be attributed, at least in part, to tirucallol. Our data extend existing data regarding the cardioprotective effect of CMG and provide a further molecular mechanism underlying the beneficial effect of CMG on endothelial function.
