Effect of glycosylation patterns of Chinese eggplant anthocyanins and other derivatives on antioxidant effectiveness in human colon cell lines

In this study, we compared the scavenging ROS of anthocyanins from Chinese eggplant var. Niu Jiao Qie and other delphinidin derivatives with different glycosylation patterns in HT-29 and HCT-116 cell lines. The eggplant anthocyanins were isolated and identified using LC-MSn and 1H/13C NMR as delphinidin-3-[(4″-trans-p-coumaroyl)-rhamnosyl (1 → 6)glucoside]-5-glucoside, also known as nasunin. Delphinidin derivatives with glycosylation only on C3 (delphinidin-3-glucoside, 3-sambubioside, or 3-rutinoside) exhibited greater effects on ROS reduction as compared to delphinidin derivatives that have glycosylation on C3 and C5 (delphinidin-3,5-diglucoside > delphinidin-3-rutinoside-5-glucoside). Nasunin has glycosylation on C3 and C5 and an acyl group (p-coumaric acid), demonstrated the least effect on ROS reduction. Meanwhile, their ROS reduction activities were consistent with glutathione reductase protein expression levels in HT-29. Although not potent in ROS reduction, nasunin and its deacylated derivatives protected cells from DNA damage in a dose-dependent manner. Taken together, our results suggest that the anthocyanins isolated from Chinese eggplant var. Niu Jiao Qie and other delphinidin have antioxidant activities in colon cancer cells and also protect cells from DNA damage.