Effect Of Selenium On Yield And Quality Of Tea And Antoxidant Activity And Anti-Hepatocarcinoma Function Of Selenium-Enriched Green Tea

Se-enriched tea leaves were processed by foliar applications of selenium and fertilizer of selenium. The influence of selenium on the yield and quality of green tea leaves harvested in different tea-producing season, the enhancement of selenium on antioxidant activity and the effects of Se-enriched tealeaves on liver cancer were determined. The results were shown as follows:Numbers of sprouts and the yield were significantly increased by application of selenium. The sweetness and aroma of green tea leaves were also significantly enhanced and bitterness were significantly decreased by application of selenium. However, no significant differences were found in sweetness, bitterness and aroma between tea leaves fertilized with selenite and selenate. Se concentration was significantly increased by selenium fertilization and tea enriched by sodium selenate had significantly higher selenium content than that sodium selenite. Total amino acid and vitamin C contents were significantly enhanced by application of selenium. Furthermore, the change of vitamin C in green tea sprayed with selenium during storage period was more stable compared with regular tea. Tea polyphenols contents were significantly decreased by fertilization of selenium. The marked difference of tea polyphenols was also found between application of selenite and selenate.The sweetness and aroma of green tea extracts were significantly increased and the astringent taste and bitterness were greatly reduced by spraying selenium during summer tea-producing season. Significant differences in astringent taste, bitterness and sweetness ofgreen tea extracts were found between sodium selenium and organically bound selenium. The total amino acid and vitamin C content of green tea were significantly increased and the ratio of polyphenols and amino acid of green tea were significantly decreased by spraying selenium. The vitamin C content of green tea during storage period was more stable with an increase of selenium content of green tea. No significant difference was obtained between sodium selenium and organically bound selenium. These results demonstrated that sensory and chemical qualities of green tea were improved by selenium.Se-enriched tea harvested in summer exhibited higher lipid inhibition activity in Linoleic acid system and Lard oxidation system. The antioxidant activity was dose-dependently correlated to selenium content in various kind of tea.In vitro antioxidant activity of Se-enriched tea produced in early spring was also enhanced by selenium application. Tea sprayed with selenite fertilizer provided significantly higher radical scavenging activity than that with selenate fertilizer. Inhibition acitivty against lipid oxidation was also significantly increased by selenium fertilizer.Results from DPPH and linoleic acid system method showed that antioxidant activities of Se-enriched tea were significantly higher than those of regular tea, selenide alone and regular tea in addition of selenide. Selenide exhibited weaker radical scavenging activity against DPPH and in linoleic acid system it showed a pro-oxidant activity of accelerating lipid oxidation. There were also significant differences between the antioxidant activities of Se-enriched tea fertilized by selenite and selenate. These results indicated difference in the chemical form of selenium in teas. This also suggested that a possible synergistic antioxidative effect existing between seleno-components and tea components in tea.Selenium contents in the blood and liver of tumor-bearing mice were significantly increased by injection of Se-enriched tea extracts and selenite in a dose-dependent manner. GSH-PX activities in mice liver and blood were also significantly enhanced. However, no marked differences were observed on the SOD activity. These results indicated that selenium in the chemical form of Se-enriched tea and selenite is easier to accumulate in mice tissue.Se-enriched tea exhibited stronger inhibition activity against hepatocarcinoma transpla -nttation tumor...