Bioassay-Guided Phytochemical Analyses and Antimicrobial Potentials of the Leaf Extract of Clematis hirsuta Perr. and Guill. Against Some Pathogenic Bacteria and Fungi

BACKGROUND: In spite of the great advances in modern medicine in recent decades, medicines of plant origin are still in use for several ailments in different parts of the world. There is always an urge to develop novel, effective and inexpensive antimicrobials. This study was aimed to evaluate the antimicrobial activity and phytochemical composition of the leaf extract of Clematis hirsuta against selected human bacterial and fungal pathogens. METHODS: The crude extracts of C. hirsuta leaves were prepared with five different solvents of varying polarity. Agar well diffusion assay on five different species of ATCC organisms, four clinical bacterial isolates, and four clinically isolated fungi were performed. The tube dilution method was used to determine the minimum inhibitory concentrations and the selected extract was subjected to bio-assay-guided fractionation using column chromatography and the active fraction obtained were pooled and GC-MS, FT-IR, and CHN analysis were conducted, and this study is actually bioassay-guided research. RESULTS: A varying patterns of antimicrobial activity against tested microorganism was observed. Acetone extract showed the highest spectrum of activity (17–32mm) in the well diffusion assay against bacteria and 16–23mm in the case of fungi. The MIC ranged from 7.5–60 mg/mL in the case of bacteria and 15–60 mg/mL against fungi. The bioassay-guided column chromatography of the acetone extract followed by GC-MS showed the presence of three major compounds, specifically O-ethylhydroxylamine (43%), 2-ethyl heptanoic acid (20.6%), and 1-nonyl cycloheptane (19.5%). The finding was confirmed by FT-IR and elemental analysis of TLC-separated fractions. CONCLUSION: The acetone extract showed better antimicrobial activity and the least minimum inhibition concentrations against bacteria compared to fungi. The observed antibacterial can be assigned to the presence of alkoxy amine, alkyl aliphatic acids, and cycloalkane. The overall findings substantiate the traditional usages of the parts of this plant, especially the leaves, in managing infectious diseases.