Date of Award

5-2012

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Food Technology

Advisor

Chen, Fneg

Committee Member

Walker , Terry H

Committee Member

Luo , Hong

Committee Member

Sharp , Julia L

Abstract

Phenolic compounds, including anthocyanins in muscadines have attracted much attention due to their diverse biological activities. With bioassays of antioxidant activities in terms of total phenolic content (TPC), total flavonoid content (TFC) total anthocyanin content (TAC), total procyanidin content (TPA), oxygen radical absorbance capacity (ORAC), ABTS radical scavenging Activity (ABTS), ferric reducing antioxidant power (FRAP), and oil peroxidation inhibitory capacity of all muscadine samples, the muscadine grapes showed strong antioxidant activities. The liquid-liquid organic solvent extraction successfully separated the anthocyanins and other phenolics to different fractions. Strong linear relationship between responses of TPC, TAC and TPA versus their antioxidant activities was assessed, which suggested that phenolic compounds in muscadine extracts contributed significantly to their antioxidant potential.
Inhibitory mode and anti-diabetic activities of the muscadine extracts on three enzymes, i.e. alpha-glucosidase, alpha-amylase and pancreatic lipase, were investigated. This study demonstrated that the phenolic and anthocyanin-rich extracts and the selected representative phytochemicals (i.e., catechin, quencertin, ellagic acid, cyanidin and cyanidin-3,5-diglucoside) obeyed the competitive mode against the enzymes. The results also showed that the muscadine extracts that possessed the strong anti-diabetes activities on the alpha-glucosidase and lipase might be ascribed to the major contributions from anthocyanins and other phenolics.
The anti-cancer activity of muscadine extracts was confirmed by the dose-dependent inhibition of cell proliferation in two other cancer cell lines, colon cancer cells HT29 and breast cancer cells MCF-7. The results indicated that, generally, the phenolics-rich and anthocyanins-rich fractions of muscadines exhibit the strong anti-proliferative activities rather than other fractions. Therefore, muscadine fruits, as well as seed and skin portions had health-promoting properties against the colon and breast cancer cell growth.
This study also successfully established a high-performance liquid-chromatography Evaporative light scattering detector (HPLC-ELSD) method, which is a universal detector able to detect almost any compound, for the simultaneous determination of phenolic acids, flavonoids and anthocyanins in muscadine grape. Further chromatographic analysis by HPLC-UV-MS identified 24 phenolics, including 5 anthocyanins. Results from the HPLC-MS quantification suggested that gallic acid, proanthocyanidins, and ellagic acid were the main phenolics in muscadines, while anthocyanins were the main ones in Noble muscadine and skin portion.

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