The antimicrobial and cytotoxic effects of the parasitic plant Hydnora abyssinica used as an antidysenteric in Namibia

Antimicrobial resistance threatens the effective treatment of dysentery and other diarrhoeal diseases, highlighting the urgent need for alternative therapeutics. Hydnora abyssinica A. Br., a root-parasitic plant with documented traditional use for gastrointestinal ailments, has been studied in parts of Africa but remains unexplored, particularly in Namibia. In this study, we evaluated it for its potential as an antidysenteric. Different extracts were prepared from the rhizome of H. abyssinica A. Br. using methanol-dichloromethane (MeOH-DCM), methanol (MeOH), and water (H 2 O). The antimicrobial activity was evaluated against five microbial strains — Enterococcus durans, Listeria monocytogenes, Escherichia coli, Shigella sonnei, and Candida albicans —using agar disc and well diffusion methods, as well as the minimum inhibitory concentration (MIC). The phytochemical content was assessed using standard methods and quantified with a Micro Reader detection system. The cytotoxicity of each extract was determined using the Sulforhodamine B assay. The lowest MIC of 3.125 mg/mL is exhibited by the MeOH extract, followed by the MeOH-DCM extract (6.25 mg/mL) and the H 2 O extract (12.5 mg/mL). Phytochemical screening revealed the presence of tannins, alkaloids, flavonoids, steroids, and saponins. The MeOH extract exhibited the highest total tannin content (TTC) (0.44 ± 0.01 mg TAE/g) as well as total phenolic content (TPC) (0.31 ± 0.05 mg GAE/g). Little to no cytotoxicity (cell viability ranged from 83.1% to 88.9% at the highest extract concentration (100 µg/mL)) was observed against the 3T3 embryonic fibroblast mouse cell line. The results of this study support the traditional use of Hydnora abyssinica A. Br. and offer new insights into the antimicrobial properties of the Namibian species, highlighting its potential as a natural therapeutic agent. It can be used as an alternative for preventing and treating stomach and throat issues, as well as dysentery and other diarrheal infections.