Antimicrobial, phytochemical, and antioxidant characterization of the leaf extracts of Clematis montana and Clematis grata

The worldwide emergence of multidrug-resistant bacterial infections among the population has impaired the existing effectiveness of antimicrobial treatments, necessitating the hunt for other alternatives. We aimed to find the antibacterial and antioxidant activities of Clematis montana and C. grata leaf extracts (both species have medicinal use among the local population). Extracts were assessed against four pathogenic bacterial strains (Escherichia coli, Salmonella typhi, Pseudomonas aeruginosa, and Staphylococcus aureus), through the agar well diffusion method. Total flavonoid content (TFC), total phenolic content (TPC), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity were quantified. Results suggested that all plant extracts, particularly those extracted with methanol, were potentially active in suppressing pathogenic bacterial growth (particularly against P. aeruginosa and E. coli) although their efficiency varied when compared to vancomycin. However, the antibacterial activity of methanolic extracts from both species was not greatly influenced by the method of extraction (maceration/soxhlet apparatus). TFC was significantly higher in the methanolic extracts of both species in comparison to the n-hexane extracts, whereas TPC and DPPH scavenging activity were detected to be highest in the methanolic extract from the leaves of C. grata. Our results suggested that the leaf extracts from both Clematis species, particularly the methanolic-based extract of C. montana, might serve as a promising source of an effective antibacterial agent.