Anti‐diabetic effect and antioxidant activity of the roasted Gugija (Lucii fructus)

Abstract

This study investigated the chemical characteristics (proximate compositions, free amino acid and mineral composition analyses), anti‐diabetic effect and antioxidant activity of its hot water‐ and ethanol‐extracts. Contents of carbohydrate, protein, lipid, and ash of the roasted Gugija were 56.3, 13.8, 12.5 and 5.1%, respectively. Three major free amino acids of the hot water‐extract of the roasted Gugija were aspartic acid (244.4 mg%), alanine (132.1 mg%), and arginine (114.7 mg%), whereas those of the ethanol‐extract were aspartic acid (174.7 mg%), alanine (10.0 mg%), and methionine (85.7mg%). The most abundant mineral in the hot water‐ and ethanol‐extracts of the roasted Gugija was potassium at 962.2 and 1023.0 mg%, respectively. Higherα‐glucosidase activity observed in the ethanol‐extract, when compared to the hot water‐extract. DPPH and ABTS radical scavenging activities of hot water‐extract were 85.1 and 80.3%, respectively, whereas those of ethanol‐extract were 88.5%, and 83.1%, respectively. The ethanol‐extract showed higher DPPH and ABTS radical scavenging activities than the hot water‐extract. Higher antioxidant activity of the ethanol‐extract than that of the hot water‐extract may be related with free amino acid compositions as well as higher polyphenol content in the ethanol‐extract (14.9 mg/g) compared to that in the hot water‐extract (12.7 mg/g).