Antioxidant activity and total phenolic content of 24 Lamiaceae species growing in Iran

The antioxidant activities of the methanolic extracts of 9 Salvia species and 15 other Lamiaceae plants growing in Iran were evaluated using ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assays. FRAP values ranged form 8.5 to 79.0 microM quercetin equivalents/g dry weight, and IC50 values in the DPPH assay from 115.7 to 1350.2 microg dry weight/mL. Salvia species showed the highest antioxidant activities. S. santolinifolia, S. eremophila and S. palestina, which have not been studied before, were the most active plants. These were more active than the previously studied species from this family, such as S. multicaulis and Marrubium vulgare. S. hydrangea and Gontscharovia popovii also showed high antioxidant activities. FRAP and DPPH assay results showed good correlations with the total phenolic contents of the plants, measured by the Folin-Ciocalteau assay (r2 = 0.925 and 0.799, respectively, p < 0.0001). In conclusion, our study shows that some Lamiaceae plants growing in Iran represent good potential sources of natural antioxidants useful for either prevention or treatment of oxidative stress-related diseases.