Anti-inflammatory effects of the partially purified extract of radix Stephaniae tetrandrae: Comparative studies of its active principles tetrandrine and fangchinoline on human polymorphonuclear leukocyte functions

We hypothesized that prevention of neutrophil from activation may underlie the myocardial protective effect of the specially processed extract of radi x Stephaniae tetrandrae (SPRST). Inflammatory responses in isolated periphe ral human neutrophils were studied in the presence or absence of SPRST. SPR ST (1-10 mug/ml) concentration-dependently prevented N-formyl-methionyl-leu cyl-phenylalanine (fMLP)- or leukotriene B-4 (LTB4)-induced neutrophil adhe sion and transmigration. Comparable results were also observed in neutrophi ls pretreated with fangchinoline (Fan) or tetrandrine (Tet), two active com ponents in SPRST. It has been reported that neutrophil adhesion/ transmigra tion is mainly Mac-1 (CD11b/CD18)-dependent and could be modulated by react ive oxygen species (ROS) production. SPRST, Tet, and Fan diminished fMLP- o r LTB4-induced Mac-1 up-regulation and ROS production. SPRST, Fan, Tot, and verapamil impaired fMLP-induced rapid intracellular alkalization, an essen tial mechanism for neutrophil ROS production, and [Ca2+], increment, sugges ting that a calcium dependent pathway might be involved. Direct G protein a ctivation by AIF(4)(-) also triggered [Ca2+], increment and adhesion that c ould be abolished by pertussis toxin and were partially reversed by SPRST, Fan, and Tot. These results reveal that inhibition of neutrophil adhesion a nd transmigration may account for SPRST's myocardial protective effect. Thi s effect of SPRST may be mediated by component(s) in addition to Tet and Fa n because combination of 0.1 mug/ml of Tot and Fan did not mimic the effect of SPRST. We conclude that SPRST exerts antiinflammatory effects by interf ering with ROS production and Ca2+ influx through G protein modulation to p revent Mac-1 up-regulation in neutrophil activation.