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 pure anthocyanins (ANC) and ANC-rich extracts from purple corn on iNS-1E pancreatic β-cells on expression of proteins related to the free fatty acid receptor-1 (FFAR1)-dependent insulin secretory pathway. A representative image of the immunoblots is shown. 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. B) Confocal laser scanning microscopy depicting two-dimensional immunofluorescence localization of nuclei (blue) and FFAR1 (red). The quantification determined by the intensity (AU) over area (μm2) of FFAR1 is shown. Data represents the mean ± SE of four independent fields of view from two independent cellular replicates. Means with different letters at the same time point are significantly different (p < 0.05) according to Tukey’s test. The cells were treated with 100 μM of pure ANC cyanidin-3-O-glucoside (C3G), delphinidin-3-O-glucoside (D3G), the semipurified C3G from purple corn pericarp (C3GP), catechin-(4,8)-cyanidin-3,5-diglucoside condensed form (CF), and 0.5 mg/mL of the ANC-rich extracts from purple corn pericarp water extract (PCW), 20 μM of the FFAR1 agonist TAK-875, or 10 μM of FFAR1 antagonist GW-1100.