Objective This study evaluated the phytochemical composition and antibacterial activity of extracts of Rumex abyssinicus roots and Verbascum sinaiticum leaves, two medicinal plants traditionally used in Ethiopia. Methods Extracts were prepared by cold maceration, and preliminary toxicity was assessed in Galleria mellonella larvae. Antibacterial activity was determined by the disc diffusion method against Staphylococcus aureus (ATCC 25923), Salmonella typhi (ATCC 19430), Escherichia coli (ATCC 25922), and Shigella sonnei (ATCC 25931). Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values were established by broth microdilution. Qualitative phytochemical screening was conducted, and principal bioactive constituents were characterized by thin-layer chromatography (TLC) and nuclear magnetic resonance (NMR) spectroscopy. Results The extracts demonstrated dose-dependent toxicity in G. mellonella , with up to 40% mortality at 100 mg/mL. Ethanol extracts of R. abyssinicus exhibited the strongest antibacterial effects, notably against S. aureus (21.3 ± 1.21 mm at 200 mg/mL), whereas chloroform extracts of V. sinaiticum showed modest inhibition at higher concentrations. The MIC ranged from 16-32 mg/mL for the ethanol extracts and 32-64 mg/mL for the chloroform extracts of both plant materials. Phytochemical analysis identified anthraquinones, saponins, and tannins in R. abyssinicus , and flavonoids and phenols in V. sinaiticum . NMR profiling revealed nine major compounds, including chrysophanol, emodin, physcion, helminthosporin, and chrysophanol-bianthrone from R. abyssinicus , and luteolin, chrysoeriol-7-O-glucoside, aucubin, and ajugol from V. sinaiticum . Conclusion These results provide a chemical basis for the observed antibacterial activity and support further investigation of these extracts and isolated metabolites as potential leads for antibacterial drug development.
Lemlemu et al. (Sun,) studied this question.