Evaluating the phytochemical composition and antimicrobial activity of Dovyalis abyssinica and Oxygonum sinuatum root extracts against Proteus mirabilis and Trichophyton rubrum

Abstract

Antimicrobial resistance (AMR) is an emerging global health crisis that indicates the inability of widely used antimicrobial treatments to work as intended. Microorganisms like Proteus mirabilis and Trichophyton rubrum, which is a causative agent of tinea pedis, are linked to antimicrobial resistance, so there is a need to look for an alternative antimicrobial agent from medicinal plants. The study was aimed at assessing the phytochemical composition and antimicrobial activity of the root extract of Dissotis abyssinica against P. mirabilis and T. rubrum, and also the root extract of Oxyanthus sinuatum. An experimental lab-based study was carried out to evaluate the antimicrobial property of methanolic root extracts of D. abyssinica and O. sinuatum. Two concentrations of the extract (0, 2, 4, 8 and 16 mg/mL) were tested. The antimicrobial activity was established by the agar well diffusion method and minimum inhibitory concentrations (MICs) by the broth microdilution method. Triplicate treatments were used for each treatment. There were positive controls of ciprofloxacin (5 µg/well) for P. mirabilis and fluconazole (25 µg/mL) for T. rubrum, and a negative control of dimethyl sulfoxide (DMSO). Phytochemical screening was also done in order to find out the presence of bioactive compounds in the extracts. Flavonoids, alkaloids, saponins and glycosides were present in the extracts. Plant extracts exhibited antimicrobial activity towards the test organisms with significantly higher antimicrobial activity as the extract concentration was raised (p < 0.0001). The antimicrobial activity of the composites was moderate to strong as per the composite mean analysis. These results showed that the methanolic extracts of roots do have some antimicrobial activity against both P. mirabilis and T. rubrum. It is the conclusion of this study that the root extract of D. abyssinica and O. sinuatum contains phytochemical constituents that exhibited antimicrobial activity against the tested microorganisms, which further supports their potential use as an alternative source of antimicrobial agents and offers a scientific basis for their ethnomedicinal uses. Further studies should be conducted by sequential extraction with at least three different solvents with different polarity, like hexane, ethyl acetate and methanol, or water, to have a more complete phytochemical profile and compare the antimicrobial activity of the extract type. A further investigation is also needed to find and characterize the specific bioactive compounds responsible for the observed antimicrobial effects.