Biological Evaluation of Some Selected Plant Species of Pakistan

Abstract

Five methanol extracts from four different plant species [Salvia nubicola B. (Laminiaceae), Hedera nepalensis K. (Araliaceae) Acer oblongifolium D. (Aceraceae) and Sorbaria tomentosa L. (Rosaceae)] were evaluated for their antimicrobial activity (by antibacterial and antifungal assays), toxicity activities (by brine shrimp cytotoxicity assay, radish seed phytotoxicity assay), antitumor activity (by potato disc assay) and antioxidant activities (by DPPH scavenging assay, ABTS+ assay, DNA protection assay and TBARS). Leaf and stem extract of A. oblongifolium exhibited significant antibacterial activity against all pathogenic strains tested, while none of the extract presented any antifungal activity against six pathogenic strains tested. Two of the five extracts (L+S) A. oblongifolium and (L+S) H. nepalensis revealed significant ED50 value i.e. 47.7 ppm and 226.8 ppm respectively in case of brine shrimp cytotoxicity assay. Growth inhibition was observed by all extracts in radish seed bioassay at high concentration (10,000 ppm). At low concentration (1000 ppm) three extracts from two plant species (leaves and flower extract of S. nubicola, stem extract of S. nubicola and stem extract of H. nepalensis) presented stimulation of growth ranging from 3.5 to 43.2%. Inhibition of tumor formation ranged from 9 to 82.9% by all extracts in antitumor potato disc assay at three different concentrations tested (1000, 100, and 10 ppm). A positive correlation was observed in the results of three of the described assays (toxicity assays i.e. brine shrimp cytotoxicity assay and phytotoxicity assay and antitumor potato disc assay). Four methanol extracts from three selected plant species i.e. Salvia nubicola (Lamiaceae), Acer oblongifoium (Aceraceae) and Hedera nepalensis (Araliaceae)) were screened for their antioxidant potential. Antioxidant activities were investigated in aqueous system by using DPPH scavenging assay, ABTS+ radical scavenging assay and DNA protection assay while in lipid system by using TBARS (Thiobarbituric acid reactive substances). Total phenolic contents were determined by using Folin-Ciocalteu reagent. Methanol extract of leaf and flower of S. nubicola showed the highest trolox equivalent values in case of DPPH scavenging assay i.e. 2484.08 ± 4.9 as well as total phenolic contents i.e. 342.08 ± 19.8. Fractionation of methanol extract of S. nubicola by semi-preparative HPLC yielded three fractions (A, B and C). Fraction B was found to be the most active in DPPH scavenging assay with highest phenolic contents as estimated by using Folin- Ciocalteu reagent. Analytical scale HPLC and LC-MS results revealed presence of rosmarinic acid in fraction B of S. nubicola while chlorogenic acid and rutin were identified as major antioxidants in methanol extract of H. nepalensis.