Tea (Camellia sinensis) contains high level of antioxidant elements and is a well-known beverage consumed worldwide. The purpose of this study is to compare different concentrations of green tea, black tea, oolong tea 861, oolong tea 732, and jasmine green tea. These five types of tea extracts were known to have antioxidative properties, reducing power, and metal ion chelating activity. The current study compared these five extracts in terms of their inhibiting effects on human malignant melanoma: A2058 and A375. To determine the cell viability between normal cell and malignant melanoma cells, an MTT assay was applied to evaluate the cytotoxic potential on human melanoma cells, with all tea extracts showing decreased cell viability with increasing tea extract concentrations. Cytotoxicity on HaCat (normal skin cells) showed no effect on the cell viabilities at lower concentrations of the tea extracts. These results suggest the antioxidative effect of five tea extracts that protect against oxidation and melanoma production, with green tea and jasmine green tea showing the lowest cell viability when tested against malignant melanoma cells.
Three pineapple cultivars smooth cayenne, Tainung 17, and Tainung 19 were processed into flesh, peel, and stem. Nine samples were analyzed for their proximate compositions and bromelain activity existed in their water extracts. Pineapple fleshes were rich in reducing sugars and soluble fiber whereas peel and stem were rich in crude fiber. Stem showed higher bromelain activity (102-247.3 U/mg). All 18 samples including water and ethanol extracts were quite effective in the scavenging ABTS + -and DPPH-radical activities and reducing power as evidenced by their low EC 50 (0.98-15 mg/mL). Water extracts of stem were more effective than their ethanol extracts. The scavenging ABTS + -radical ability was highly related with total phenols and flavonoids. Overall, peel and stem of pineapple showed high amounts of reducing sugars and soluble fiber, and higher bromelain activity and exhibit effective antioxidant activities. These wastes of pineapple would be utilized to develop as a sweet supplement or functional product.
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