In vitro investigation of phytochemical, antioxidant and antimicrobial activities of Harpagophytum procumbens seeds extracts

Abstract

Medicinal plants contain bioactive substances that are highly bioavailable in extracts or pure molecules, making them promising for therapeutic applications and precursors for chemo-pharmaceutical semi-synthesis. Harpagophytum procumbens (Devil’s Claw) is widely recognized as one of the most potent therapeutic herbs. This study aimed to extract seeds from H. procumbens using two types of solvents and to assess both qualitative and quantitative aspects of the extracts. The two extracts were evaluated for antibacterial and anti-biofilm activities using agar well diffusion assays against four bacterial isolates and two yeast isolates. Qualitative analysis identified the presence of alkaloids, flavonoids, tannins, saponins, and terpenoids. The active components detected were: alkaloids (12.69%), flavonoids (3.25%), total phenolic compounds (24.58%), total terpenoids (8.55%), and total steroids (1.25% for methanolic and 4.55% for petroleum ether). Both methanolic and petroleum ether extracts exhibited antioxidant activities of approximately 85.33% and 74.19%, respectively, compared to ascorbic acid, which had an antioxidant effect of 67.99% at a concentration of 200 µg/ml. The extracts demonstrated a broad spectrum of activity against all tested bacteria (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus pyogenes) and fungi (Candida albicans, C. tropicalis, C. parapsilosis). At a concentration of 1000 µg/ml, the seed extracts showed the highest bactericidal activity, with inhibition zones ranging from 10 to 22 mm. Moreover, both extracts exhibited greater anti-biofilm activity at 1000 µg/ml compared to lower concentrations. Our study found that seed extracts of H. procumbens possess significant antibacterial and antioxidant activities, particularly at a concentration of 1000 µg/ml.