Biomarker Compounds in Muscadine and their Effects on Colon Cancer Cells

Muscadine (Vitis rotundifolia) is a native and valuable fruit crop in Southeastern US. Today muscadine products are commercially available as nutraceuticals. Major concerns in nutraceuticals are product quality and their effects on human health. This study was conducted to evaluate muscadine nutraceutical powder derived from pomace (cv. Noble) for biomarker compounds and their effects on colon cancer cell lines. The powder was extracted after acid hydrolysis. The extract (CE) was further fractionated to obtain flavonoid and anthocyanin fractions (FAF). Total phenolic (TP) and flavonoid (TF) contents, and individual biomarker compounds in each fraction were analyzed using colorimetric assays and HPLC-PDA, respectively. The TP and TF contents in the fractions were higher compared to those of CE. The main polyphenol present in CE was ellagic acid, not resveratrol as in table grapes. The major anthocyanins present were 3,5-diglucosidic anthocyanins in contrast to monoglucosidic anthocyanins present in table grapes. The effects of CE and FAF were tested in two colon cancer cell lines, HT-29 and HCT-15, for cytotoxicity and cell cycle arrest. Cell proliferation assays and flow cytometry data showed that FAF decreased viable cell proliferation in both cell lines, and evidence of G1 arrest as compared to CE. These results indicate the bioactivity of fractions rich in flavonoids and anthocyanins may be higher than that of CE in inhibiting colon cancer cell growth.