Inhibitory effect of dauricine on platelet activating factor released from calcimycin-induced mouse peritoneal macrophages

The effects of dauricine (Dau) on the release of platelet activating factor (PAF) from mouse peritoneal macrophages stimulated by calcimycin (A-23187) was studied. The method of sodium [3H]acetate incorporating into macrophages to synthesize PAF was set up for the first time. Calcimycin (0.2 mumol/L) significantly induced mouse peritoneal macrophages to utilize sodium [3H]acetate to synthesize PAF. PAF released from macrophages medium fluid increased as the concentration of sodium [3H]acetate increased. The maximal amount of PAF released from macrophages was attained by incubating macrophages with sodium [3H]acetate (250 mumol/L) and calcimycin (2 mumol/L) over 30 min. Extracted by CHCl3:CH3OH:H2O (2:2:1.8), separated by thin layer chromatography (TLC) and determined by liquid scintillation counting, PAF released was inhibited significantly by Dau both in time (10-30 min) and dose (1-1000 mumol/L) dependent manners. The IC50 of Dau for the formation of PAF was 2.5 mumol/L. On the same condition PAF release was also significantly inhibited by quinacrine at 500 mumol/L. The results indicate that Dau is a potent inhibitor of PAF synthesis in mouse peritoneal macrophages.