Abstract
Naturally occurring plant phenols, which included ellagic acid (EA), tannic acid (TA), caffeic acid (CA), and ferulic acid (FA), were tested for their superoxide anion radical (SOR)-scavenging activities. SOR was produced by interaction of tumor promoters, i.e. phorbol-12-myristate-13-acetate (PMA) or mezerein, in vitro with murine peritoneal macrophages. The levels of SOR were assessed microscopically by counting the number of formazan-positive (F+) cells/250 cells produced due to the reduction of nitroblue-tetrazolium. PMA at a concentration of 0.1μg/1.85×106cells/0.5ml induced maximum formation of SOR both in resident and thioglycollate-elicited cells, whereas mezerein induced the maximum formation of SOR at 10μg/1.85×106cells/0.5ml. All the tested polyphenols were able to inhibit the formation of SOR induced by the tumor promoters to a variable degree. The maximum inhibition by EA of SOR formation induced by PMA or mezerein was at a concentration of 250μM or 125μM, respectively. The polyphenols CA, TA, and FA were more effective in inhibition of SOR stimulation at a concentration of 120 and 60μM with promoters PMA and mezerein, respectively. However, ferulic acid was found to be the most effective inhibitor of SOR formation.
