Purification of alpha-glucosidase inhibitors from grape extract

摘要

ABSTRACTPURIFICATION OF ALPHA-GLUCOSIDASE INHIBITORS FROM GRAPE EXTRACTbyGAYLE SHIPPAugust 2012Advisor: Dr. Kevin ZhouMajor: Nutrition and Food ScienceDegree: Master of ScienceDiabetes and its complications are steadily growing and remain major causes of morbidity and mortality in the U.S. Intestinal á-glucosidases play a crucial role in controlling postprandial blood glucose. For this reason, one attractive prevention and/or treatment strategy for type-2 diabetes is the inhibition of á-glucosidase. The effectiveness of á-glucosidase inhibitors (AGIu27s) for diabetes treatment is well documented in numerous animal and human clinical studies. Grape pomace extract (GPE) has recently found in our laboratory to selectively inhibit alpha-glucosidases without inhibiting alpha-amylase, leading to inhibition of postprandial hyperglycemia in diabetic animals. The present study was designed to identify effective GPE by fractionating and isolating active compounds that inhibit alpha-glucosidases in a specific GPE. From enzyme assay testing, results revealed Fraction 1 active, showed 35% inhibition (p u3c0.05) compared to the positive control 87.64% and negative control -.565%. HPLC was conducted on F1, which yielded two potential active compounds (peaks) following ACN gradient system method. F1 will undergo future structure identification and elucidation.Fractionation of GPE yielded a very small amount of active F1 for testing. Open column chromatography using HP20 and coarse C18 for scale-up of GPE separation but the resulting fraction failed to show significant inhibition on alpha-glucosidases. Further method development is needed if the collected peaks are not active compounds.