Antioxidant and glycosidase inhibitory activity of ethyl acetate fraction and isolated components from walnut kernels

• Main Authors: Hao-Yi Hsiung, 熊皓儀
• Other Authors: Jeng-De Su
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/84583589289710310132

碩士 === 東海大學 === 食品科學系 === 102 === Diabetes is associated with deficiencies in insulin secretion or action. Excess reactive oxygen species are built up with chronic hyperglycemia, and are subsequently contributing to oxidative stress and complications. Antioxidants have important roles in disorders involving oxidative stress. Glycosidases are not only involved in human digestion, but also affect the generation of many metabolic diseases such as diabetes, the most important glycosidases are α-amylase and α-glucosidase. Walnut kernels, Juglans regia L., has long been used in traditional Chinese medicine. Previous studies have demonstrated that walnut kernels have antioxidant, antiatherogenic, antiproliferative, antitumor activities and anti-aging effects of brain. There were literature related to the ethanol extract of walnut leaves for hypoglycemic effect in rats, but in walnut kernels of research related to blood sugar regulation which is quite rare. This study was to investigate the antioxidant activity of walnut and assess their glycosidases ability to inhibit expect from the issue of walnut purified antioxidant active ingredients and regulate blood sugar, and then issue the relevant health research and development functions of health food. Walnut kernels was extracted with methanol, and the methanol extracts were added distilled deionized water, and then extracted with the proportional n-hexane, ethyl acetate and n-butanol successively. These extracts were analysed wth antioxidation and glucosidase activity were isolated and purified with the structure of the screening and identification of the active ingredient. The results showed that ethyl acetate fraction of walnut kernels had better resistance to oxidation and glycolytic enzyme inhibitory activity, after the separation of the liquid column chromatography and HPLC purified effective active ingredients. Finally, the structure identified two kinds of antioxidant and glycosidase inhibitory activity of the purified material by UV, MS, 1H-NMR and 13C-NMR analyses. The isolated components were identified two hydrolyzable tannins, tellimagrandin I(1) and casuarictin(2). Two isolated components showed the strongest antioxidant activity by trolox equivalent antioxidant capacity(TEAC), which were 99.58%(1) and 99.60%(2) respectively. And the two isolated components gave the highest inhibition rates against α-glucosidase, which were 66.57％(1) and 68.59％(2)% respectively. Two isolated component were efficient in inhibiting α-amylase, with inhibition rates of 14.08％(1) and 13.88％(2).