Carissa bispinosa (L.) Desf. ex Brenan is traditionally employed in the management of oral infections. Nevertheless, scientific evidence supporting its therapeutic effects and phytochemical profile remains scarce. This research aimed to evaluate the protective potential of leaf and stem extracts from C. bispinosa against oral pathogens. Phenolic and tannin levels were quantified via the Folin-Ciocalteu assay following extraction with various solvents. Minimum inhibitory concentrations (MIC) of the extracts were determined through microdilution against fungal strains (Candida albicans and Candida glabrata) and bacterial strains (Streptococcus pyogenes, Staphylococcus aureus, and Enterococcus faecalis). Antioxidant capacity was examined using 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and ferric reducing power (FRP) assays. Cytotoxicity of the leaf acetone extract was assessed with the methylthiazol tetrazolium (MTT) method.
The highest phenolic content in leaf extracts was observed in the methanol fraction (113.20 mg TAE/g), while the hexane extract showed the greatest tannin level at 22.98 mg GAE/g. Among stem extracts, the acetone fraction exhibited the highest phenolic content (338 mg TAE/g), and the stem extract overall provided the maximum tannin content (49.87 mg GAE/g). The methanol leaf extract achieved the lowest MIC (0.31 mg/mL), matching the stem ethanol extract at 0.31 mg/mL. The stem methanol extract displayed the strongest DPPH scavenging activity (IC50, 72 µg/mL), whereas the stem ethanol extract demonstrated the highest FRP with an absorbance of 1.916. The leaf acetone extract showed low cytotoxicity, with an LC50 of 0.63 mg/mL. Findings from this investigation support the protective role of C. bispinosa in combating oral infections.
