Presenting author: Candice Mazewski

Co-authors: Katie Liang, and Elvira Gonzalez de Mejia

Department of Food Science and Human Nutrition

Foods associated with lowering risk of colorectal cancer include fruits, vegetables, whole cereals and legumes. Anthocyanins (ANC), pigments in the flavonoid class, have shown potential to provide various health benefits, including prevention and suppression of colon cancer. The objective of this study was to evaluate the anti-proliferative effect of ANC-rich extracts from a variety of plant sources on HCT-116 and HT-29 human colorectal cancer cells in comparison to oxaliplatin and to investigate the mechanism of action. Eleven extracts were tested on both cell lines which consisted of fruits (red and purple grape), vegetables (sweet purple potato and purple carrot), legumes (black and purple bean, black lentil and black peanut), and cereals (sorghum, black rice and blue wheat). An accelerated solvent extraction system was used for anthocyanin extraction at 50 °C from each material; only water was used as solvent for extraction. The chemical composition of the extracts was compared through HPLC, mass spectrometry, total ANC and phenolic concentration, as well as color parameters such as hue, and chroma. The effect of chemical composition was correlated with anti-proliferative capabilities. Total polyphenols ranged from 47.3 to 382.3 mg gallic acid/g dry extract. There was a strong correlation between HCT-116 and HT-29 cell inhibition and total polyphenols (r=0.87 and 0.77, respectively), as well as with hue (r=-0.81 and -0.58, respectively). HPLC profiles were very distinctive for all extracts, predominating in cyanidin-3-O-glucoside, peonidin 3-O-glucoside, and delphinidin 3-O-glucoside. The three most potent extracts were selected to perform further mechanistic studies: black lentil (BL), sorghum (SH), and red grape (RG). On HCT-116 cells, the IC50 values for BL, SH, and RG were 0.9±0.1, 1.0±0.1, and 1.5±0.1 mg/mL (p<0.05), respectively, and on HT-29 cells, they were 1.4±0.1, 1.7±0.1, and 2.0±0.2 mg/mL, respectively (p<0.05). The extracts showed important changes on markers of apoptosis such as Bcl-2, survivin, livin, and TNF-α. The results of the present study suggest that BL, SH, and RG extracts exhibit a potential to inhibit human colon cancer proliferation in vitro, possibly through promotion of apoptosis. They also indicated that there were potential correlations between chemical composition and human colon cancer cell inhibition.