Evaluation of the antioxidant and biological properties of muscadine grape seed extracts.

摘要

The phenolic compounds in grapes are responsible for their antioxidant activity and have been reported to possess biological properties such as anti-carcinogenic, anti-mutagenic, anti-inflammatory and antimicrobial properties. There has been extensive research on these properties in the Vitis vinifera grape, but limited research in the muscadine grape. The objectives of this research were (i) to optimize the extraction conditions of phenolic compounds from muscadine grape seeds using food grade solvents, (ii) to characterize and quantify the phenolic compounds present in Carlos muscadine grape seed extracts, (iii) to assess the oxidative stability of the grape seed extract, (iv) to evaluate the antimicrobial activity of the optimal muscadine grape seed extract, and (v) to evaluate the effect of muscadine grape seed extract on MCF-10A breast cells.;Carlos muscadine grape seeds were manually removed from the skin and pulp, then either freeze-dried or oven-dried. A response surface analysis design was used to determine the optimal extraction conditions for the highest recovery of phenolic compounds from the muscadine grape seed extracts. The phenolic compounds were extracted from the delipidized muscadine grape seeds using a Dionex Accelerated Solvent ExtractorRTM 200 following a two factor composite design. The two factors for this study were solvent and temperature. Both ethanol in combination with water and ethyl acetate in combination with water were separately used and compared to determine the solvent and concentration resulting in the highest recovery of phenolic compounds. The solvent percentages ranged from 35% to 95% (increasing in 15% increments) and temperature ranged from 75°C to 150°C with 25°C increases. The optimal extraction conditions were determined by measuring the total hydroxyl groups and free radical scavenging activity of the muscadine grape seed extracts using the Folin-Ciocalteu and oxygen radical absorbance capacity assays, respectively. A Thermo Quest Surveyor HPLC coupled with a Finnigan LCQ DUO mass spectrometer was used to identify and quantitate the phenolic compounds present in the extracts. The optimal extraction conditions for the highest recovery of phenolic compounds consisted of the freeze-dried seeds extracted using 65% ethanol and 35% water at 150°C, with total phenolic and oxygen radical absorbance capacity values of 5.87 mg GAE/g and 60.32 muM-TE/g of seeds, respectively. The four major phenolic compounds quantified in the muscadine grape seed extract were epicatechin, catechin, gallic acid and ellagic acid, with values of 76.7 mug/ml, 32.3 mug/ml, 3.32 mug/ml, 0.97 mug/ml, respectively.;The oxidative stability, antimicrobial activity and anti-carcinogenic properties of the extracts were also evaluated. For the oxidative stability index, the muscadine grape seed extract had an overall induction period of 4.6 hours. For the evaluation of the antimicrobial activity, the agar well diffusion method was performed on E. coli O157:H7, Listeria monocytogenes, and Salmonella typhimurium. The muscadine grape seed extract was effective against all three bacteria, but exhibited the greatest inhibition against Listeria monocytogenes. Of the pure compounds evaluated in the antimicrobial study, ellagic was the only phenolic compound that had an inhibitory effect on the bacteria tested. Ellagic acid also showed its greatest inhibitory effects against Listeria monocytogenes. As a result of the findings in this research, muscadine grape seed extracts contain phytochemicals with antioxidant and antimicrobial properties that can be used in a variety of applications including food ingredients, food supplements and other nutraceutical applications.