Bioactive compounds and therapeutic potential of Salvia fruticosa Mill. leaves against microorganisms and osteosarcoma

Many studies reported the cytotoxic effect of Salvia fruticosa Mill. (S. fruticosa) on different cancer cell lines. This study aims to investigate the methanolic extract of S. fruticosa leaves in terms of its polyphenolic content, antioxidant activity, antimicrobial activity against different microorganisms, and cytotoxic activities on the U2OS osteosarcoma cell line. Fourier Transform Infrared Spectroscopy was performed to detect the major functional groups in the extract. The extract's total carbohydrate content was found to be 45.63 ± 3.33 mg glucose equivalent, the total phenolic content was 170.68 ± 6.52 mg caffeic acid equivalent, and the total flavonoid content was 44.71 ± 5.67 mg rutin equivalent per gram of the extract. Polyphenolic bioactive compounds of the extract were identified and quantified using Liquid chromatography-electrospray ionization-tandem mass spectrometry, demonstrating that naringenin is the most abundant polyphenolic compound, quantified at 3137.22 µg of the standard per gram of the extract. The antioxidant activity was evaluated using the 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity assay, revealing an IC₅₀ of 25.17 ± 0.304 µg/mL, which demonstrates the extract's concentration-dependent activity. The extract also exhibited good antimicrobial activity against gram-positive S. aureus and B. subtilis, and the fungus S. cerevisiae with MIC values of 1.562 mg/mL, while the MIC for gram-negative E. coli was observed at 12.5 mg/mL. The extract showed a significant reduction in U2OS cell viability with an IC₅₀ of 77.58 ± 3.47 µg/mL after 72 h of incubation, while it had no significant effect on the viability of human skin fibroblasts. These findings suggest that the methanolic extract of S. fruticosa leaves shows potent antioxidant activity due to its high content of polyphenolics; hence, the extract could be a potential treatment for different microbial infections and osteosarcoma.