Ethanolic extracts of Tinospora cordifolia and Alstonia scholaris show antimicrobial activity towards clinical isolates of methicillin-resistant and carbapenemase-producing bacteria.

The aim of this study was to determine the in vitro antimicrobial activity of crude extracts of three plants from Ayurveda tradition (Tinospora cordifolia, Alstonia scholaris, Crataeva nurvala) against reference microbial strains and clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) and carbapenemase-producing Klebsiella pneumoniae. IC50 values were obtained by micro-dilution methods meeting the requirements of the NCCLS standard. The cytotoxicity of the extracts was also investigated on a mammalian cell line. Extracts displayed a variable degree of antimicrobial activity and did not interfere with mammalian cell proliferation. T. cordifolia and A. scholaris exhibited a higher inhibitory activity against clinical isolates of MRSA and carbapenemase-producing K. pneumoniae compared with reference strains, while C. nurvala exhibited a different behaviour. An antifungal activity towards Candida albicans was observed for A. scholaris extract. Results indicate that constituents from T. cordifolia and A. scholaris may be a potential source of new therapeutic strategies for infectious diseases.