Catechin free radical mechanism

The ability of the constituents of tea, particularly (+)-catechin, to inhibit LDL oxidation has been investigated [46] as expected, LDL modified by cells or copper-induced oxidation was endocytosed and degraded by macrophages more quickly than native LDL. However, in the presence of (-i-)-catechin, the rates of endocytosis and degradation were similar to those of native LDL [46]. In addition to the inhibition of LDL oxidation, flavonoids such as catechin, rutin, and quercetin, at levels of 10-20 mmol/L, minimize the cytotoxicity of oxidized LDL [47]. Moreover, cells preincubated with these flavonoids were observed to be resistant to the cytotoxic effects of previously oxidized LDL (47, 48). The postulated mechanisms by which flavonoids protect against the cytotoxicity of oxidized LDL are consistent with their antioxidant and free radical-scavenging properties [4]. 

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