Survey of antimutagenic effects of ethanolic extract of propolis by Salmonella typhymurium/microsome

In this study, antimutagenesis effect of ethanolic extract of propolis by Ames test against two mutagenic substances named azide sodium and potassium permanganate in the presence and the absence of microsomal homogenate of mouse liver (S9) has been investigated. In this experimental study at first, different concentrations of ethanolic extract of propolis (0.1-5%) for determining minimum inhibitory concentration (MIC) against tester strains were used. Then by Ames test, antimutagenesis effect was assessed in nontoxic extent. In this test, various strains of Salmonella typhymurium (TA100 and TA97) that contained selective mutation in their operon histidine, were used. Mutant strains (His-) were grown on culture media containing minimum salt and glucose in the presence of mutagen substances above. So only those bacteria that were reversed by mutation (His+) could grow and form colonies on culture media. If antimutagen (EEP) and mutagen substances were gathered, reversed mutation would be reduced and the rate of mutation inhibition could be calculated by means of formula. The differences between the averages of revertants per plate of the sample in relation to the mutagens were analyzed using SPSS software and one-way ANOVA. The resulted MIC values clearly showed that ethanolic extract of propolis at 5% concentration has antibacterial activity against Salmonella typhymurium, but in 0.1-4% concentrations, such effects were not seen. Findings also showed that propolis in such concentrations could neutralize mutagenic effects of those substances in a dose dependent manner. Finally we found that ethanolic extract of propolis that contains different kinds of major and important substances like flavonoids, has good antimutagenic effects and the best concentration for obtaining such effect is in 4% which also was confirmed with microsomal results. The mechanism of antibacterial effect of propolis is complex and it has no analogy to any classic antibiotics, but it should be emphasized that bacterial cell division is inhibited by propolis. Some researchers also argue that propolis could inhibit DNA-dependent RNA polymerase.