Antimicrobial Potential of Extracts of Hyptis suaveolens (L) Poit. Leaves on Some Gram Positive Bacterial Isolates

Abstract

This study investigated the antibacterial potential of the methanolic extract and other different fractions obtained from the crude extract of Hyptis suaveolens leaves on some selected Gram positive bacterial isolates. It also assessed the antibiotic susceptibility patterns of the test isolates.  Powdered sample of Hyptis suaveolens was extracted with methanol and water in ratio 3:2 and partitioned with n-hexane, chloroform, ethyl acetate and butanol in ascending order of their polarity. The filtrates were concentrated with rotary evaporator and kept for further use. All extracts were screened for antibacterial activity using agar well diffusion method. The minimum inhibitory and bactericidal concentrations of the extracts were also determined. Antibiotics sensitivity test was performed using Kirby Bauer method of antibiotics susceptibility test. The results showed that the extract had activity at a concentration of 35 mg/ml on 8 of the test bacteria with zones of inhibition ranging between 14.50 ± 0.71 mm and 18.00 ± 1.41 mm for test bacteria while the zones of inhibition for the standard antibiotics ranged between 16.00 ± 0.00 mm and 23.00 ± 1.41 mm. The zones of inhibition of the active fraction (ethyl acetate) ranged between 12.00 ± 0.00 mm and 17.00 ± 2.83 mm. The MICs of the extract ranged between 1.09 mg/ml and 35.00 mg/ml while that of the fraction ranged between 0.16 mg/ml and 5.00 mg/ml. The MBCs of the extract ranged between 2.19 mg/ml and 35 mg/ml while that of the active fraction ranged between 0.31 mg/ml and 5.00 mg/ml. All the test bacteria showed 100% resistance to amoxicillin and had multiple antibiotics resistance to other commercially available antibiotics. The study concluded that the plant possessed antimicrobial properties at higher concentrations and could be used in the treatment of various infections. Although, ethyl acetate showed highest antibacterial activity, its concentration was much less than the crude extract. Hence, the study also concluded thatethyl acetate; among other solvents was the most suitable for the extraction of antimicrobial compounds from the leaves of Hyptis suaveolens.