Antimicrobial activity, cytotoxicity, and qualitative phytochemical composition of aqueous and methanolic leaf extracts of Physalis peruviana L. (Solanaceae)

Abstract

Background: The high morbidity and mortality associated with microbial infections and the ineffectiveness of conventional antibiotics due to inappropriate use and resistance warrant alternative stratagems. Aim: We investigated the antimicrobial, cytotoxicity, and qualitative phytochemical composition of the aqueous and methanolic leaf extracts of Physalis peruviana L. (Solanaceae) based on its ethnomedicinal information. Methods: The antimicrobial activity of the extracts was investigated using the disk diffusion technique. The brine shrimp lethality assay method was used to determine the cytotoxicity of the study extracts on brine shrimp nauplii. Qualitative phytochemistry of the study extracts was performed using standard procedures. Results: The two extracts did not possess antimicrobial activity against P. aeruginosa and were either inactive or slightly inactive against the other microbes at concentrations of ≤ 50 µg/ml. Notably, the aqueous extract exhibited high to very high activities against E. coli and S. aureus and very high to remarkable activities against B. cereus. The methanolic extract showed remarkable activity at concentrations of ≥200 µg/ml against E. coli, moderate to very high against S. aureus, high to very high against B. cereus, and moderate to high against C. albicans. The aqueous extract's minimum inhibitory concentrations (MICs) were 50 μg/ml (E. coli and B. cereus), 100 μg/ml (S. aureus), and 200 μg/ml (C. albicans). The minimum bactericidal concentration concentrations (MBCs) of the aqueous extract were 100 μg/ml (E. coli and B. cereus), 200 μg/ml (S. aureus), while the minimum fungicidal concentration (MFC) for C. albicans was 400 μg/ml. The MICs of the methanolic extract were 25 μg/ml for E. coli, S. aureus, and B. cereus and 100 μg/ml for C. albicans, and the MBCs were 100 μg/ml for E. coli, S. aureus, and B. cereus, and the MFC for C. albicans was 200 μg/ml. The aqueous was non-toxic, while the methanolic extract was slightly toxic to brine shrimp nauplii, indicating their relative safety. Various phytochemicals were detected in the study extracts, depicting broad pharmacologic activity, including antimicrobial activity. Conclusion: The aqueous and methanolic leaf extracts of P. peruviana may serve as a source of efficacious and safe novel antimicrobial agents upon further evaluation.