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 biotransfarmation of catechins of g reen tea [GT] to theaflavins and thearubigins. BT was found to be more effi cient than GT and its individual catechin constituents in proportionate amo unts in abrogating production of NO and O-2(-) in activated murine peritone al macrophages. In a reconstitution system of BT that is free of all catech ins, 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 t he most important constituent in down-regulating synthesis of iNOS. Clearly , BT containing theaflavin is an excellent chemopreventor against reactive oxygen and nitrogen species. (C) 2001 Academic Press.