The comparative study among different fractions of muscadine grape ‘Noble’ pomace extracts regarding anti-oxidative activities, cell cycle arrest and apoptosis in breast cancer

As a by-product of wine making, pomace contains rich amounts of phenolic compounds that can be potentially utilized as raw materials to make beneficial products especially for the anti-cancer agents including the breast cancer. Muscadinia rotundifolia 'Noble' is a wine-making grape cultivar, and to better use 'Noble' pomace, the most effective phenolic fractions in cancer inhibition must be identified. In this study, anti-oxidative activities of three separated fractions of 'Noble' pomace (F1, F2 and F3) were compared in 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) radical scavenging (DPPH and ABTS) assays as well as the ferric-reducing antioxidant power (FRAP) assay. The ability of different fractions to induce cell cycle arrest and apoptosis in MDA-MB-231 breast cancer cells was also evaluated by flow cytometry and Western blot analysis. Fraction F3, which contained a mixture of anthocyanidins and ellagic acids, exhibited the strongest anti-oxidative activity, as determined at both low and high concentrations in the DPPH and FRAP assays. F3 also demonstrated the greatest ability to induce apoptosis via caspase activation and cell cycle arrest by downregulating cyclin A and upregulating p21. F3 was thus the most effective bioactive fraction among those prepared from muscadine grape 'Noble' pomace.