Identification of volatile orange juice components that increase the IL-4 and IL-10 formation in buccal cells

The aim of this study was to investigate the immune modulatory effect of orange juice and its components. For this purpose, epithelial buccal cells (KB) were exposed to orange juice or orange juice fractions containing the dry matter, the volatile compounds (aqueous distillate), or individual non-volatile or volatile components. Intracellular formation of the anti-inflammatory cytokines IL-4 and IL-10 was analyzed by flow cytometry. Exposure to whole orange juice and the DM resulted in a decrease in IL-4 and IL-10 formation compared to non-treated control cells. The sugars and organic acids were identified as active components inducing this pro-inflammatory effect. In cells treated with the aqueous distillate in higher concentrations, an increased IL-4 and IL-10 formation was analyzed. In order to identify the anti-inflammatory compounds in the aqueous distillate, cells treated with the aqueous distillate were analyzed by GC-MS. Aroma compounds identified therein were limonene, linalool and α-terpineol. Subsequent studies on the intracellular IL-4 and IL-10 production revealed that linalool and limonene had no significant effects, whereas α-terpineol had a stimulating effect. This anti-inflammatory effect on cytokine production in buccal cells by the orange juice aroma component α-terpineol has been shown for the first time.