Preliminary study of the antioxidant activity of Vitis rotundifolia (muscadine grape) extracts using different methods

Vitis rotundifolia (muscadine grape) is a grapevine species found in humid subtropical climate areas such as south-central and southeastern United States. Previous researches have reported the bioactivity of the muscadine grapes and our purpose is to look for valuable compounds from plants with medicinal properties or health benefits. The plant used in this research was collected in the organic garden at St. Thomas University. Muscadine plant extracts were analyzed by TLC (Thin Layer Chromatography) using polar and non-polar solvents, and the spots were developed and visualized with Iodine and UV light. The antioxidant activity assays were performed with the extracts of oven and freeze-dried leaves, grapes, and roots. Antioxidants are compounds capable of hindering process of oxidation caused by reactive oxygen species and raiding free radicals. The free radical scavenging activity (FRS) was evaluated with the DPPH reagent, and is reported as ascorbic acid equivalent antioxidant capacity, measured spectrophotometrically at 517 and 520 nm. The estimation of the ferric reducing power (FRP) with potassium ferricyanide was obtained, and the absorbances of the colored complex in the extracts were taken at 700 nm. Total Phenolic Content (TPC) assay of the samples using Folin-Ciocalteu reagent for all parts of the plant showed up the grapes exhibiting the highest antioxidant content compare with the leaves and roots. Cytotoxicity assay on chemical extracts were tested on breast cancer cells and methylthiazol tetrazolium (MTT) assays were used to quantify cytotoxicity. Preliminary data indicated the extracts were not cytotoxic at the concentration tested.