Determination of in vitro antioxidant activities of different extracts of Marrubium parviflorum Fish et Mey. and Lamium amplexicaule L. from South east of Turkey.

Abstract

This study was designed to determine the in vitro antioxidant activities of methanol and hexane extracts of Marrubium parviflorum Fish et Mey. and Lamium amplexicaule L. from Lamiaceae and their total phenolics, flavonoids, flavonols and phenolic acid content. The extracts were screened for their possible antioxidant potentials by β-carotene/linoleic acid, 2,2-diphenyl-1-picrylhydrazyl(DPPH) and ABTS, power reducing, metal chelating and DNA nicking assays. The methanol extracts of these plants exhibited significant antioxidant activities determined by different these assays and contained significant levels of phenolics. Total phenolic content were determined by Folin-Ciocalteu assay. Phenolic contents of the methanol extracts were found 332.93 ± 26.90 and 183.36 ± 14.78 mg GAE/g dry weight, respectively. The amounts of phenolic acids in the extracts were characterized by a reverse-phase High Performance Liquid Chromatography(HPLC) method that used in the gradient elution employing diode array detection. The most abundant phenolic acid detected by HPLC-DAD in the methanol extracts was rosmarinic acid in M. parviflorum whereas valinic acid was observed in the methanol extract of L. amplexicaule. This study shows that methanol extracts of the plants have higher activities than their hexane extract, except DNA protecting activity (p < 0.05). Key words: Marrubium parviflorum, Lamium amplexicaule, antioxidant activity, phenolics, high performance liquid chromatography.