Effects of flavonoids extracted from Scutellaria baicalensis Georgi on hemin–nitrite–H2O2 induced liver injury

Hemin–nitrite–H2O2 system may play a role in liver oxidative injury in some pathological events. In this paper, the effects of the three active components of the root of Scutellaria baicalensis Georgi, i.e. baicalin, baicalein and wogonin, on hemin–nitrite–H2O2 induced liver injury were studied in liver homogenate, liver microsome and human hepatoblastoma cell line HepG2 cells. It was found that hemin–nitrite–H2O2 could induce liver homogenate protein nitration, lipid peroxidation and liver microsome protein oxidation; it also caused a decrease of HepG2 cells viability. Baicalein, baicalin and wogonin could inhibit protein nitration and lipid peroxidation in liver homogenate as well as in HepG2 cells in a dose-dependent manner, the inhibition order was baicalein > baicalin ≫ wogonin. These three flavonoids also inhibited the oxidation of protein in liver microsome, the decrease of cell viability and the content of GSH in HepG2 cells, among which baicalin represented the most inhibitory effect. Besides, hemin–H2O2 induced cell injury could be augmented with the existence of nitrite, indicating protein nitration involved in hemin–nitrite–H2O2 induced liver injury. These results demonstrated hemin–nitrite–H2O2 could induce liver injury through oxidizing or nitrating different biomolecules. Baicalein, baicalin and wogonin could inhibit hemin–nitrite–H2O2 induced liver injury in dose-dependent manners by inhibiting oxidation and nitration.