Antioxidant and antimicrobial activities of phenolic extracts of mulberry (Morus indica L.) and mint (Mentha spicata L.) leaves

In the present research work, total phenolic content(TPC), antioxidant, and antimicrobial activities of phenolic extracts of mulberry and mint leaves were evaluated. Yield of extraction and TPC of mint leaves extract were higher than those of mulberry leaves extract. TPC of mulberry and mint leaves extracts were 130.5 and 158.7 (mg gallic acid/g dry extract), respectively. The effectiveness of phenolic extracts in inhibiting lipid peroxidation of human erythrocyte membrane was studied. Results showed that the amount of thiobarbituric acid-reactive substances formed by oxidation of membrane lipids were lowered in the presence of both extracts. Moreover, both phenolic extracts would able to enhance the antioxidative capacity of erythrocyte membrane through protecting the reduced glutathione (GSH) against oxidation. Both the extracts were able to inhibit the growth of both G(+) and G(-) bacteria. E. coli and S. aureus were the most sensitive bacteria to mulberry and mint extracts, respectively. Mulberry leaves extract had higher antioxidant and antimicrobial activity than mint extract, in spite of its lower TPC. Both the extracts exhibited dose-dependent antioxidant and antimicrobial activities.