Pro-oxidative effects of Chinese herbal medicine on G6PD-deficient erythrocytes in vitro.

Glucose-6-phosphate dehydrogenase (G6PD)-deficient subjects are susceptible to chemical-induced oxidative haemolysis. Little is known concerning the haemolytic properties of Chinese herbal medicine on G6PD-deficient subjects. Our objective was to investigate the pro-oxidative effect of 18 commonly used Chinese herbal medicine (CHM) on human G6PD-deficient red blood cells. G6PD-deficient (n=10) and normal (n=10) whole blood samples were incubated with water extracts of CHM. The resulting levels of reduced glutathione (GSH) and methaemoglobin (MetHb) were determined by biochemical assays. Rhizoma Coptidis significantly reduced GSH level by 48.9+/-5.4% (at 1 mg/mL) in the G6PD-deficient erythrocytes (P<0.001) compared with the respective control group without challenge. Similar dose-dependent responses were observed at higher concentrations of Cortex Moutan, Radix Rehmanniae, Radix Bupleuri, Rhizoma Polygoni Cuspidati and Flos Chimonanthi (P<0.01, 5-10 mg/mL). In addition, the levels of MetHb were elevated significantly when challenged with Rhizoma Coptidis (2.8 fold at 5 mg/mL) and Cortex Moutan (3.4 fold at 10 mg/mL). This is the first report on the pro-oxidative action of CHM on G6PD-deficient blood samples in vitro as demonstrated by the decrease of GSH and increase of MetHb. G6PD-deficient subjects should restrain from excessive consumption of these pro-oxidative herbs.