Browsing by Subject "Potato"
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Item Influence of genetic variability on specialty potato functional components and their effect on prostate cancer cell lines(2009-05-15) Reddivari, LavanyaThe influence of genotype (selection), location, and year on antioxidant activity (AOA), total phenolics (TP), total carotenoids (TC), phenolic and carotenoid composition was studied using specialty (colored) potatoes (Solanum tuberosum L.) from the Texas Potato Variety Development Program, grown at two Texas locations (McCook and Dalhart), and in two years (2003 and 2004). Chlorogenic acid, gallic acid, catechin, caffeic acid, and malvidin-3-(p-coumaryl rutinoside)?5-galactoside were the major phenolics, and lutein and violaxanthin were the major carotenoids identified. The AOA, TP, and TC and phenolic composition differed significantly with genotype, location and year. However, genotypic effects were larger than location and year effects. Selection CO112F2-2 was high in all the measured parameters and also stable across locations and years, suggesting that this selection could be used as a parent in breeding varieties with improved health benefits. The AOA, TP and chlorogenic acid content were highly significantly correlated with one another. The effects of whole specialty potato extracts, fractions and individual compounds on LNCaP (androgen-dependent) and PC-3 (androgen-independent) prostate cancer cells were also investigated. Ethanol extract of the selection CO112F2-2 (5 ?g chlorogenic acid eq/ml), the anthocyanin fraction (AF; 5 ?g chlorogenic acid eq/ml), gallic acid and chaconine showed potent anti-proliferative properties and increased the cyclin-dependent kinase inhibitor p27 levels in LNCaP and PC-3 cells. Induction of apoptosis was cell context dependent and associated with JNK (c-Jun NH2-terminal Kinase) and Erk (extracellular signal regulated kinase) activation. Cell death pathways, induced by potato extract and the AF, were associated with Erk and JNK activation, and these kinases activated caspase-independent apoptosis through nuclear translocation of endonuclease G (endo G) and apoptosis-inducing factor (AIF) in both cell lines. Induction of caspase-dependent apoptosis was also kinase-dependent but was observed only in LNCaP cells. Kinase inhibitors reversed this nuclear translocation of endo G and AIF. This is the first report showing that the cytotoxic activities of potato extract/AF in cancer cells were due to activation of caspase-independent apoptosis.Item The effects of cooking, storage, and ionizing irradiation on carotenoids, antioxidant activity, and phenolics in potato (Solanum tuberosum L.)(Texas A&M University, 2005-11-01) Blessington, TyannPast research conducted by our lab demonstrated that potatoes contain significant levels of phytochemicals important to human health. However, since potatoes are not consumed raw, it is important to determine the effects of processing on these levels. Therefore, the changes in carotenoid content, antioxidant activity, and phenolic content were investigated using combinations of cultivars, cooking methods, storage treatments, and low-dose ionizing irradiation. Carotenoid content was measured via absorbance at 445 nm, 450 nm, and HPLC identification. Antioxidant activity was measured initially and at stabilization via the DPPH method and phenolic content was measured via the Folin method and HPLC identification. Microwaved, baked, fried, and raw potato samples contained more carotenoids than boiled samples. The samples microwaved, baked, and fried contained higher antioxidant activity and phenolics than the boiled or raw samples. However, the compound quercetin dihydrate appeared to decrease with cooking. Carotenoids, antioxidant activity, and phenolics appeared to decrease with storage; however, high storage temperatures and long storage times were believed to cause a dehydration and concentration of compounds, which caused levels to be equal to or greater than before storage. However, this decreasing trend was not linear and there were multiple significant interactions. The compound chlorogenic acid appeared to be quite sensitive to high temperature storage. Irradiation dose appeared to have only a minor, if any, effect on carotenoid levels. The interaction between storage time and irradiation dose was very influential on antioxidant activity. In early stages of storage, higher doses of irradiation had greater antioxidant activity, while, with continued storage, low doses had higher antioxidant activity. Exposure to irradiation appeared to cause an increase in phenolic content, determined by the Folin method. There may be a stimulation, induction, or release of some compounds due to processing; however, its magnitude is not believed to be as great as genetic control. The effects of processing can not be denied and should continue to be investigated. Future studies investigating the health properties of fruits and vegetables, particularly potatoes should include processing effects.