Acute toxicity assessment of bioactive constituents from Salvia algeriensis (Desf.) extracts: a promising natural agent against clinical bacterial isolates and pathogenic fungi

Salvia species are emerging as promising therapeutic agents due to their diverse bioactivity against various pathologies. This study was conducted to investigate the phytochemical profile, antimicrobial activity, and acute toxicity of hydromethanolic extracts from Salvia algeriensis (Desf.) leaves, flowers, and roots. Chemical reaction tests and chromatographic analysis were employed to determine the chemical composition, while microdilution was used to determine the minimum inhibitory concentration (MIC) of the tested microorganisms. The acute toxicity of the leaf extract was carried out following the rules and guidelines of OECD 425. Toxicity parameters in Swiss albino mice after a single dose of 500 mg/kg and 2000 mg/kg were evaluated. According to the preliminary phytochemical screening results, terpenoids and polyphenols (flavonoids and tannins) were found in all parts of the plant, but coumarins were only found in the root extract. The HPLC-DAD analysis revealed the presence of 16 phenolic compounds in varying amounts across the three extracts, of which rosmarinic acid, quercetin, caffeic acid, and 3-hydroxybenzoic acid were the most abundant. Selective antimicrobial activity was noticed, with the root extract demonstrating the strongest effect against the two fungal strains tested. MIC values ranged from 0.3 to 10 mg/mL, and Gram-positive bacteria generally showed greater susceptibility compared to Gram-negative bacteria. The LD50 was found to be greater than 2000 mg/kg. There were no overt clinical symptoms of toxicity. Body weights, organ weights, and temperatures were not significantly altered, and hematological analysis showed no significant differences. Salvia algeriensis (Desf.) extracts emerge as potential candidates for natural, non-toxic antimicrobial agents.