Anthocyanin-rich phenolic extracts of purple root vegetables inhibit pro-inflammatory cytokines induced by H2O2 and enhance antioxidant enzyme activities in Caco-2 cells

Highly pigmented root vegetables are ideal sources of phytochemical antioxidants particularly anthocyanins. The objective of this study was to characterise the phenolic composition in a purple variety of carrot and potato by examining the aglycone profiles and their antioxidative stress activity. Cyanidin and petunidin were the dominant phenolics among 11 identified aglycones in carrot and potato, respectively. The anthocyanin-rich phenolic extracts not only showed strong antioxidant activities by direct radical scavenging, but more importantly they significantly reduced H2O2-induced interleukins (IL)-1β, IL-6, IL-8 and tumour necrosis factor (TNF)-α in Caco-2 cells. In addition, the extracts were able to restore the intrinsic antioxidant defences as seen in significantly elevated antioxidant enzyme activities and glutathione concentration. These results suggest that purple varieties of carrots and potatoes rich in anthocyanins can ameliorate oxidative stress mediated intestinal inflammatory responses, leading to restoration of the impaired redox balance, ultimately improved health.