Black tea is a powerful chemopreventor of reactive oxygen and nitrogen species: comparison with its individual catechin constituents and green tea.
Production of black tea [BT] results in biotransformation of catechins of green tea [GT] to theaflavins and thearubigins. BT was found to be more efficient than GT and its individual catechin constituents in proportionate amounts in abrogating production of NO and O2(-) in activated murine peritoneal macrophages. In a reconstitution system of BT that is free of all catechins, stepwise addition of catechins showed that though all the constituents contributed to the overall effect of BT, theaflavin was the most powerful in abrogating NO production. RT-PCR analysis also showed theaflavin to be the most important constituent in down-regulating synthesis of iNOS. Clearly, BT containing theaflavin is an excellent chemopreventor against reactive oxygen and nitrogen species.
Sarkar
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Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Calcutta, 700 032, India.
Bhaduri
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D000818:Animals; D044946:Biflavonoids; D002392:Catechin / Q000031:analogs & derivatives / Q000494:pharmacology*; D002478:Cells, Cultured; D018890:Chemoprevention; D004790:Enzyme Induction / Q000187:drug effects; D005285:Fermentation; D017737:Macrophages, Peritoneal / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000235:genetics; D052247:Nitric Oxide Synthase Type II; D012333:RNA, Messenger / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013662:Tea / Q000737:chemistry / Q000378:metabolism*
D044946:Biflavonoids; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D013662:Tea; C056068:theaflavin; D009569:Nitric Oxide; D002392:Catechin; C045651:epigallocatechin gallate; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse