Anthocyanins from purple corn activate free fatty acid-receptor 1 and glucokinase enhancing in vitro insulin secretion and hepatic glucose uptake
A) Effect of the free fatty acid receptor-1 (FFAR1) antagonist GW-1100 in the insulin secreting activity of pure anthocyanins ANC and ANC-rich extracts from purple corn in iNS-1E pancreatic β-cells compared to positive control C+ (glucose). B) Insulin secreting activity of pure ANC and ANC-rich extracts from purple corn in glucose-starved pancreatic β-cells compared to negative control C- (starving conditions). The cells were treated with different concentrations of pure ANC (1 μM– 100 μM) cyanidin-3-O-glucoside (C3G), delphinidin-3-O-glucoside (D3G), pelargonidin-3-O-glucoside (Pr3G), peonidin-3-O-glucoside (P3G), the semipurified C3G from purple corn pericarp (C3GP), catechin-(4,8)-cyanidin-3,5-diglucoside condensed form (CF), the purple corn pericarp water extract (PCW) (0.125 mg/mL– 1.0 mg/mL), and a FFAR1 agonist TAK-875 (5 μM– 20 μM) in the presence or absence of 10 μM GW-1100. Results are expressed as the mean ± SD of three independent experiments. Bars with different letters means statistical difference (p < 0.05) as determined by Tukey’s test.