Novel Tripeptides with alpha-Glucosidase Inhibitory Activity Isolated from Silk Cocoon Hydrolysate

Abstract

Active compounds with antidiabetic potential were isolated from silk peptide E5K6 by consecutive ultrafiltration and gel filtration using Biogel P-2 and RS-HPLC using a YMC-Pack Pro C18 column. The highest alpha-glucosidase inhibitory activity of silk peptide E5K6 resulted from fractions With MW <1 kDa. The activities of,gel-filtered fractions from silk peptide E5K6 of <1 kDa were assayed in vitro, demonstrating that the fourth peak (F4) had the highest alpha-glucosidase inhibitory activity (IC(50) = 37 1 mg/mL) F4 of silk peptide E5K6 was separated by HPLC into two peaks Moreover, the purified compounds were identified as Gly-Glu-Tyr (GEY, MW = 367 Da) and Gly-Tyr Gly (GYG, MW = 295 Da) according to amino acid sequences, and their alpha glucosidase inhibitory activities (IC(50)) were 2 7 and 1 5 mg/mL, respectively