inhibitory effects of ethanolic, methanolic and hexanolic extracts of propolis on the activity and structure of tyrosinase

Introduction: tyrosinase is a key enzyme in the biosynthesis of melanin, which plays a crucial role in determining mammal’s skin and hair color. in this experimental study, the inhibitory effect of different extracts of propolis were investigated on tyrosinase activity.methods: tyrosinase activity was measured in the presence of ethanolic, methanolic and hexanolic extracts of propolis by using thermal denaturation (catecholase and cresolase reaction). also the tyrosinase stability was examined in the presence of the extracts with the chemical (urea) denaturation method. data were analyzed with spss software using anova and tokey post hoc test.results: tm was 56.1 °c for tyrosinase in the absence of the extract and 47.4, 53.4 and 40.2 °c in the presence of ethanolic, methanolic and hexanolic extracts of propolis, respectively. also δg 25 °c values were obtained 16.03 in the absence of the extracts and 13.5 (p<0.05), 15.3 and 13.3 (p<0.05) kj/mol, respectively in the presence of ethanolic, methanolic and hexanolic extracts of propolis. in chemical denaturation, cm was obtained 3.11 in the absence of the extracts and 15.8 (p<0.01), 11.9 (p<0.05), and 12.5(p<0.05) mm, respectively in the presence of ethanolic, methanolic and hexanolic extracts of propolis.conclusion: ethanolic, methanolic and hexanaloic extracts of propolis are appropriate inhibitors for the tyrosinase. these reduce the thermal and chemical tyrosinase stability.