In vitro antibacterial and antifungal activities of methanolic leaf extracts of Eucalyptus lanceolatus and Lawsonia inermis, individually and in combination

Abstract

The growing problem of antimicrobial resistance has boosted interest in plant-derived compounds as potential sources of novel antimicrobial drugs. The present study was conducted to investigate the in vitro antibacterial and antifungal activities of crude methanolic leaf extracts of Eucalyptus lanceolatus and Lawsonia inermis alone and in combination at equal ratio. Dried leaves were powdered and extracted with methanol. The antibacterial activity against Klebsiella pneumoniae, Pseudomonas aeruginosa and Staphylococcus aureus was tested by agar-well diffusion method. Individual extracts were tested at 400 and 1000 µg/mL and the combination at a nominal concentration of 1000 µg/mL. Antifungal activity was tested against Aspergillus fumigatus and Aspergillus flavus on Sabouraud dextrose agar at 1000 µg/mL, terbinafine was used as positive control and dimethyl sulfoxide as negative control. L. inermis and E. lanceolatus showed 75% and 50% relative inhibition against K. pneumoniae and 35% and 30% against P. aeruginosa at 1000 µg/mL, respectively. The combination showed 78.2% inhibition against S. aureus as against the individual extracts which showed 65.2% and 39.1%. In these settings, the inhibition of fungi was modest. L. inermis showed 22% against A. flavus, while E. lanceolatus showed 15% against A. fumigatus. These preliminary results require more standardized susceptibility testing, formal interaction assays, phytochemical chara characterization, and cytotoxicity evaluation to prove any therapeutic significance.