Leucas aspera (Willd.) L.: Antibacterial, antifungal and mosquitocidal activities

The various organic extracts from the leaves of Leucas aspera were screened for their antibacterial, antifungal and larvicidal activities against selected bacterial, fungal strains and mosquito larvae of Culex quinquefasciatus. Antimicrobial activity was carried out using the disc-diffusion method and MIC of the extract was tested by the broth microdilution method. The results revealed that all the extracts showed antibacterial and antifungal activities against selected microbes at 1, 2.5, 5 and 10 mg/disc concentrations. The maximum zone of inhibitions were recorded in dichloromethane (DCM) leaf extract of L. aspera (Willd.) L. against S. aureus (23.4 ± 2.90 mm), E. coli (20.3 ± 1.56 mm), B. subtilis (17.1 ± 2.04 mm), P. aeruginosa (16.5 ± 1.05 mm), P. vulgaris (16.1 ± 2.56 mm) and K. pneumonia (15.1 ± 3.66 mm) at 10 mg/disc concentration. The DCM extract of L. aspera (Willd.) L. exhibited significant growth inhibition against T. viride (29.2 ± 2.00 mm), C. albicans (24.4 ± 0.80 mm), A. flavus (22.8 ± 0.36 mm) and E. floccosum (19.5 ± 2.17 mm). The minimum inhibitory concentration (MIC) ranges between 75.5-425.5 μg/mL and 125-425 μg/mL against bacterial and fungal pathogens, respectively. In addition, DCM extracts of L. aspera (Willd.) L. showed 100% larvicidal activity against C. quinquefasciatus at 1000 ppm concentration. The biological activities could contribute to the medicinal properties of the plants, and also provide more scientific authentication of traditional medicinal plants to fight against the various infectious diseases.