Effect of gamma and microwave irradiation on antioxidant and antimicrobial activities of Cinnamomum zeylanicum and Echinacea purpurea

The effect of gamma and microwave irradiation on antioxidant and antimicrobial activities of Cinnamomum zeylanicum and Echinacea purpurea were investigated. In this study, all samples were exposed to gamma irradiation at doses 10, 15, 20 and 25 kGy and microwave irradiation at power of 100, 180 and 300 W for 5 min. In order to undergo the sequence expriments, the hydroalcoholic (EtOH 50%) extracts of two medicinal plants were prepared. The antioxidant activity of irradiated and control samples were evaluated by DPPH radical scavenging (RS), ferric reducing power (FRP), β-carotene bleaching (BCB) and total phenolic content (TPC) of sampels. In order to study the antimicrobial activity, for determination of minimal inhibitory concentration (MIC) on E. coli and S. aureus, broth diluting method was used. Regarding gamma irradiation, no significant effect on antioxidant and antimicrobial activities of Cinnamon was observed. However, at doses higher than 10 kGy, higher radical scavenging activity (RSA) of was observed for Cinnamon extract (by DPPH method). By increasing the irradiation dose, FRP and TPC of samples increased and no adverse effect was observed on antimicrobial activity of Echinacea extract. Microwave treatments of Cinnamon, had no significant effect on antioxidant and antimicrobial activities of its extract. However, at 300 W an increase in antioxidative and antimicrobial activities of Echinacea extract was observed.