Phytochemical composition, antioxidant, and antimicrobial activities of hydroethanolic extracts of Pteleopsis suberosa and Piliostigma thonningii used in traditional medicine in Togo

The rise of multidrug-resistant isolates to conventional antibiotics underscores the urgent need to identify alternative bioactive compounds. This study aimed to assess the antimicrobial potential of Pteleopsis suberosa and Piliostigma thonningii , two Togolese medicinal plants traditionally used to manage vaginal, pulmonary, gastric, and skin infections. Total hydroethanolic extracts were prepared from different plant organs through maceration. Qualitative phytochemical screening was performed using standard staining methods to identify major classes of secondary metabolites. Total flavonoid content was quantified via a spectrophotometric assay. Antioxidant activity was evaluated using the phosphomolybdate reduction method and the FRAP assay. Antimicrobial activity of the extracts was assessed using the solid-well diffusion technique and a microplate microdilution method. The highest hydroethanolic extraction yield was obtained from the trunk bark of P. thonningii (22.67%). Phytochemical screening revealed the presence of tannins, saponins, alkaloids, phenols, triterpenes, and reducing sugars. The greatest total flavonoid content was recorded in P. thonningii leaves (313.82 µg Eq R/mg DE). P. suberosa leaves exhibited strong in vitro antioxidant activity, with values of 90.70 Eq AA/g DE and 430.50 µmol Eq FeSO₄ /mg DE. The largest inhibition zone (20 mm) was observed with P. thonningii trunk bark extract against Candida albicans . Moreover, P. suberosa trunk bark and both organs of P. thonningii (leaves and trunk bark) exhibited a low MIC of 1.562 mg/mL against Staphylococcus aureus . The findings of this study support the traditional use of these plants in the treatment of infections caused by the tested microbial strains. Nevertheless, further investigations are required to isolate and characterize the active compounds responsible for the observed biological activities and to evaluate the toxicity profiles of both species.