Relationships among antioxidants, phenolics, and specific gravity in potato cultivars, and evaluation of wild potato species for antioxidants, glycoalkaloids, and anti-cancer activity on human prostate and colon cancer cells in vitro.

Understanding the influence of environment and correlation/relationships among traits is necessary in selection for crop quality improvement. Therefore, correlations among antioxidant activity (AOA), total phenolics (TP), phenolic composition, and specific gravity (SPG) in four potato (Solanum tuberosum, L.) cultivars (Atlantic, Red La Soda, Russet Norkotah, and Yukon Gold) grown in nine states (California, Idaho, Michigan, Minnesota, New Jersey, North Carolina, Oregon, Texas, and Wisconsin) for three years, and in 15 advanced selections grown in Texas were investigated. Cultivars within and between locations were significantly different in AOA, TP, and SPG. Significant effects of cultivar, year, location and their interactions on AOA, TP, and SPG were observed. There were significant positive correlations among the four cultivars between AOA and TP, and negative correlations between AOA and SPG, and between TP and SPG. However, correlations between AOA and SPG, and between TP and SPG, in the advanced selections were not significant. Some tuber-bearing wild potato species were higher in AOA and TP than the commercial cultivars; therefore, they could be used as parental material in breeding for high AOA and TP. However, use of wild species that might be higher in total glycoalkaloids (TGA) than cultivars could result in progenies with high TGA if the traits are positively correlated. To elucidate the relationships among AOA, TP and TGA, accessions of Solanum jamesii and S. microdontum from the US Potato Genebank were screened for these traits and their correlations determined. Also, anti-proliferative and cytotoxic effects of 15 S. jamesii tuber extracts (5 and 10 ?g/ml) on human prostate (LNCaP) and colon (HT-29) cancer cells was determined in vitro. Alpha-solanine and ?-chaconine were found in both species, while tomatine and dehydrotomatine were quantified in some S. microdontum accessions. Both species were higher in all above traits than the Atlantic, Red La Soda, and Yukon Gold cultivars. More than 90% of S. jamesii accessions had TGA levels < 20 mg/100g fresh weight, while only two accessions of S. microdontum, P1 500041 and PI 473171, exhibited TGA < 20 mg/100g. Neither AOA nor TP was significantly correlated with TGA in both species. Also, individual phenolics were not correlated with TGA. Solanum jamesii accessions significantly reduced proliferation of HT-29 (5 and 10?g/ml) and LNCaP (10?g/ml) cells and were not cytotoxic compared to the control (DMSO). Therefore, since AOA and TP were not found to be correlated with TGA, using wild accessions in breeding for increased health promoting compounds would not necessarily increase glycoalkaloids in newly developed potato cultivars.