Antibacterial activity of selected Libyan medicinal plants against Pseudomonas aeruginosa and Escherichia coli

Abstract

The aim of the present study was to assess the antibacterial activity of Zizyphus Vulgaris, Laurus nobilis, Thymus capitatus, Cistus salvifolius, Arbutus pavarii, Rhus tripartata, Pistacia atlantica against reference strains of Pseudomonas aeruginosa and Escherichia coli. For this purpose, extract of leaves was obtained by 96% chloroform, 95% ethanol or petroleum ether. Antibacterial activity and minimum inhibitory concentration (MIC) for different extracts of each plant was evaluated. Cistus salvifolius and Arbutus pavarii were the most effective, as the values of inhibition zones were 9.0 ± 0.89 mm and 8.0 ± 1.7 mm for E. coli, and 14.0 ± 0.84 and 10.0 ± 0.81 mm for P. aeruginosa, respectively. Zizyphus Vulgaris and Laurus nobilis showed no effect on E. coli and Thymus capitatus showed no effect on P. aeruginosa. Rhus tripartata plant extract caused an inhibition of E. coli growth at 50 mg/ml, while Zizyphus Vulgaris, Thymus capitatus caused this inhibition at 100 mg/ml. However, the minimal inhibitory concentration was 200 mg/ml for other plant extract. The minimal inhibitory concentration for P. aeruginosa was 50 mg/ml for Rhus tripartata extract, 100 mg/ml for Thymus capitatus, and 200 mg/ml for other tested plant extracts. The petroleum ether extracts of the plants did not exhibit any effect on the growth of P. aeruginosa and E. coli. However, the chloroform extract of Thymus capitatus has inhibited the growth of E. coli (7 mm). The results of the present study indicate that ethanolic extract of Cistus salvifolius and Arbutus pavarii, Rhus tripartata has the most effective and potent antibacterial activity.