In vitro and in vivo hypoglycemic effects of cyanidin 3-caffeoyl-p-hydroxybenzoylsophoroside-5-glucoside, an anthocyanin isolated from purple-fleshed sweet potato

•Purple sweet potato Shinzami had highest anthocyanin content of the 6 cultivars.•Shinzami-derived anthocyanin restricted glucose secretion in HepG2 cells.•The same anthocyanin had hypoglycemic effects on hyperglycemic mice. Anthocyanins are major components of purple sweet potatoes (PSP) with antioxidant, anti-obesity, and antidiabetic activity. In this study, we evaluated the hypoglycemic effects of 12 individual anthocyanins purified from PSP (Korean variety Shinzami). We separated the anthocyanins using liquid chromatography with diode array detection and electrospray ionization/mass spectrometry (LC-DAD-ESI/MS). Three anthocyanins were selected through a radical scavenging activity test. We examined whether individual anthocyanins inhibited glucose secretion in HepG2 cells (hepatic gluconeogenesis). Additionally, we determined the effect of each anthocyanin on fasting blood glucose levels in 6-week-old male C57BL/6J mice fed a 60% high-fat diet for 14 weeks. Mice were evaluated at 0, 1, 2, and 4 h after oral administration of anthocyanins (80 mg/kg), an anthocyanin-rich-fraction (80 mg/kg), positive control (metformin, 80 mg/kg), and distilled water (control). Cyanidin 3-caffeoyl-p-hydroxybenzoylsophoroside-5-glucoside (PEAK9) was the main PSP anthocyanin that inhibited hepatic glucose secretion and reduced blood glucose.