"Purification of alpha-glucosidase inhibitors from grape extract " by Gayle M. Shipp

Access Type

Open Access Thesis

Date of Award

January 2012

Degree Type

Thesis

Degree Name

M.S.

Department

Nutrition and Food Science

First Advisor

Kequan Zhou

Abstract

ABSTRACT

PURIFICATION OF ALPHA-GLUCOSIDASE INHIBITORS FROM GRAPE EXTRACT

by

GAYLE SHIPP

August 2012

Advisor: Dr. Kevin Zhou

Major: Nutrition and Food Science

Degree: Master of Science

Diabetes 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 (AGI's) 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 <0.05) 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.

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