Antibacterial activities of aqueous and methanol leaf extracts of Solanum incanum Linn. (Solanaceae) against multi-drug resistant bacterial isolates

Abstract

It is estimated that about 80% of the world's population use medicinal plants either in their crude unmodified form or partially in their modified semi-synthetic form for their medical care. The present study investigated the antibacterial activity of aqueous and methanol leaf extracts of Solanum incanum Linn. (Solanaceae) against multiple drug resistant (MDR) clinical isolates (Streptococcus pyogenes, Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas aeruginosa). The extraction was done by cold maceration. The antibacterial susceptibility of the bacteria was carried out using agar well diffusion method. The phytochemical screening revealed presence of cardiac glycosides, carbohydrates, reducing sugars and ketoses in both extracts. In addition, resin, flavonoid, terpenoids and steroids were found in the methanol extract while saponins and alkaloids were found in the aqueous extract. Evaluation of the antibacterial activities of S. incanum Linn. showed that the aqueous and methanol extracts have significant activities against S. pyogenes, S. aureus, K. pneumoniae and P. aeruginosa. Highest antibacterial activity was shown for both aqueous (MIC=2.62 mg/ml, MBC= 60 mg/ml) and methanol (MIC=7.50 mg/ml, MBC>80 mg/ml) extracts against P. aeruginosa, respectively. The least antibacterial activity was shown for both aqueous (MIC=0.05 mg/ml, MBC=20 mg/ml) and methanol (MIC=5.00 mg/ml, MBC=80 mg/ml) extracts against K. pneumonia. Thus, S. incanum Linn. (Solanaceae) can be said to have antibacterial activities against MDR bacterial isolates.