Plant polyphenols inhibit benzoyl peroxide-induced superoxide anion radical production and diacylglyceride formation in murine peritoneal macrophages

Naturally occurring plant polyphenols, which include ellagic acid (EA), tan nic acid (TA), caffeic acid (CA), and ferulic acid (FA), were tested for th eir superoxide anion radical (SOR)-scavenging activities. SOR were produced by interaction of the tumor promoter benzoyl peroxide ((BPO) with murine p eritoneal macrophages in vitro. The levels of SOR were assessed microscopic ally by counting the number of formazan-positive cells per 250 cells produc ed by the reduction of nitro blue tetrazolium. BPO at a concentration of 15 mu g/1.85 x 10(6) cells/0.5 ml induced maximum formation of SOR in residen t and thioglycollate-elicited cells. All the tested polyphenols were able t o inhibit the formation of SOR induced by the tumor promoter to a variable degree. Inhibition of BPO-induced SOR formation by polyphenols was in the f ollowing order: FA > TA > CA > EA. BPO stimulated the accumulation of diacy lglycerol (DAG) in resident and elicited macrophages with concurrent releas e of choline equivalents from macrophages. Polyphenols inhibited DAG accumu lation, which paralleled the inhibition of choline equivalent release. FA w as observed to be the most effective and EA the least effective inhibitor o f SOR formation, DAG accumulation, and release of choline equivalents. It i s likely that inhibition of SOR formation might be due to some interference in the cellular lipid metabolism and phospholipid equivalent deacylation a nd choline release.