Bioactive profiling of four Sphagnum species: phytochemicals, antioxidant, antimicrobial, and cytotoxic effects

Bryophytes have attracted increasing interest due to their unique repertoire of bioactive compounds. This study evaluated the phytochemical composition and biological activities of methanolic extracts obtained from four Sphagnum taxa (Sphagnum compactum, Sphagnum teres, Sphagnum subsecundum and Sphagnum nemoreum). Preliminary phytochemical screening indicated the presence of phenolic compounds, while alkaloids were not detected. Subsequent LC-MS/MS analysis enabled the identification of several phenolic constituents, including myricetin, quercetin, cinnamic acid, rutin, gallic acid, caffeic acid, chlorogenic acid and ascorbic acid. Antimicrobial assays demonstrated that S. teres and S. compactum exhibited the strongest activity, particularly against Corynebacterium xerosis, Micrococcus luteus, Bacillus cereus and Candida utilis, whereas the remaining taxa showed moderate to low antimicrobial effects, mainly against Gram-positive bacteria. Antioxidant capacity, assessed using DPPH and phosphomolybdate assays, was notable and dose-dependent, while comparatively lower activity was observed in the CUPRAC assay. Cytotoxicity evaluations performed on MKN-28 human gastric cancer cells and normal human umbilical vein endothelial (HUVEC) cells revealed no significant toxic effects at the tested concentrations. Overall, Sphagnum extracts demonstrated selective antimicrobial and antioxidant properties, supporting their potential relevance for future pharmaceutical and industrial applications.