Fig. 4. Inhibitory effect of total saponin from Korean red ginseng (TSKRG) on cyclooxygenase (COX)-1 and thromboxane A₂ synthase (TXAS). (A) Effect of TSKRG on COX-1 activity in microsomes of platelets. The microsomal fraction (10 μg of total protein) of platelets was pre-incubated with or without various concentrations of TSKRG for 30 min at 37℃. The TSKRG-induced COX-1 activity was assayed with COX-1 fluorescent assay kit. (B) Effect of TSKRG on TXAS activity in platelet microsomes. The microsomal fraction (20 μg total protein) of platelets was pre-incubated for 5 min at 37℃ with or without various concentrations of TSKRG. The reaction was initiated by adding 5 μM prostaglandin H₂ (PGH₂) and terminated by adding 1 M citric acid. The activity was measured as the production of PGH₂- mediated thromboxane B₂ (TXB₂) by TXB₂ EIA kit. The data are given as the mean±SD (n=4). ^**p<0.001 compared with that of TSKRG-nontreated microsomal fraction of platelets.