Modulation of cytokine secretion by pentacyclic triterpenes from olive pomace oil in human mononuclear cells

Olive pomace oil, also known as “orujo” olive oil, is a blend of refined-pomace oil and virgin olive oil, fit for human consumption. Maslinic acid, oleanolic acid, erythrodiol, and uvaol are pentacyclic triterpenes, found in the non-glyceride fraction of orujo oil, which have previously been reported to have anti-inflammatory properties. In the present work, we investigated the effect of these minor components on pro-inflammatory cytokine production by human peripheral blood mononuclear cells in six different samples. Uvaol, erythrodiol, and oleanolic acid significantly decreased IL-1β and IL-6 production in a dose-dependent manner. All three compounds significantly reduced TNF-α production at 100 μM; however, at 10 μM, uvaol and oleanolic acid enhanced the generation of TNF-α. In contrast, maslinic acid did not significantly alter the concentration of those cytokines, with the exception of a slight inhibitory effect at 100 μM. All four triterpenes inhibited production of I-309, at 50 μM and 100 μM. However, uvaol enhanced I-309 production at 10 μM. The triterpenic dialcohols had a similar effect on MIG production. In conclusion, this study demonstrates that pentacyclic triterpenes in orujo oil exhibit pro- and anti-inflammatory properties depending on chemical structure and dose, and may be useful in modulating the immune response.