Metabolomic analysis, extraction, purification and stability of the anthocyanins from colored potatoes.

Colored potatoes have many health benefits because they are rich in anthocyanins. However, the constituent and property of anthocyanins in colored potatoes have not been systematically studied yet. Herein, metabolomic analysis was carried out to investigate the chemical composition of anthocyanins in the four different colored potatoes. After that, the extract and purification conditions, and the stability of the anthocyanins were further studied. The results indicated that the four colored potatoes contained abundant of polyphenols, flavonoids, and anthocyanins. Cyanidin, delphinidin, and malvidin were identified as the major anthocyanidins in purple potatoes, whereas red potatoes were mainly consisted of pelargonidin and its derivatives. 84.47 mg C3GE/100 g DW of anthocyanins was obtained at the optimal conditions, which could be effectively purified macroporous resin of D101. Moreover, the anthocyanins were sensitive to pH, temperature, light, redox agents, and divalent or trivalent metal ions, but stable to sugars and univalent metal ions.

Inhibition mechanism of α-glucosidase inhibitors screened from Tartary buckwheat and synergistic effect with acarbose.

Tartary buckwheat has been shown to provide a good antihyperglycemic effect. However, it is unclear which active compounds play a key role in attenuating postprandial hyperglycemia. Presently, acetone extract from the hull of Tartary buckwheat had the best effect for α-glucosidase inhibition (IC50 = 0.02 mg/mL). Twelve potential α-glucosidase inhibitors from Tartary buckwheat were screened and identified by the combination of ultrafiltration and high-performance liquid chromatography coupled with mass spectrometry. Myricetin and quercetin exhibited the highest anti-α-glucosidase activity with IC50 values of 0.02 and 0.06 mg/mL, respectively. These inhibitors manifested different types of inhibition manners against α-glucosidase via direct interaction with the amino acid residues. The results of structure-activity relationships indicated that an increase in the number of -OH on the B-ring greatly strengthened α-glucosidase inhibitory activity, but glucoside and rutinoside replacement on the C-ring obviously weakened this influence. Furthermore, a synergistic effect was observed between inhibitors with different inhibition manners.