Radical Scavenging, Proteases Activities, and Phenolics Composition of Bark Extracts from 21 Medicinal Plants

Abstract

Stem barks derived from twenty-one medicinal plants were extracted in methanol (100%) and acetone-water (70 : 30 v/v) and at room as well as at reflux temperature conditions. Total phenolic contents, determined using FC (Folin Ciocalteu) reagent, ranged from 528 to 715 mg GAE/g of crude extract. 15 out of 21 plants showed DPPH activity more than 90% and the rest of plants exhibited the activity in the range of 87–89%. The methanolic extract ofP. granatumobtained at room temperature showed the highest antiradical activity (96%). The extracts with similar % radical scavenging of DPPH∙showed significant variation in EC50value. Radical scavenging activity ofE. rostrata, M. champaca, A. modesta, P. roxburghii, P. longifolia, E. suberosa,andF. infectoriawas evaluated for the first time. A strong correlation between total phenols and antiradical activity was exhibited withRvalues ranging from 0.7580 to 0.8874 indicating a linear relationship The extracts phenolic composition was studied by HPLC. All extracts showed remarkable antioxidant activity (87 to 96%) while moderate activity was exhibited against protease (22 to 56%). Gallic acid, tannic acid, quercetin, rutin, catechin, hesperidin, and cinnamic acid were identified as the major phenolic acids in the extracts of selected medicinal plants.