Propolis impairs cellular proliferation by promoting oxidative damage and disrupting macromolecular composition in a yeast model

Propolis, a bee-derived resin with diverse pharmacological properties has an unclear dose-dependent effect on cellular homeostasis. This study evaluated the toxicological effects of a standardized 10% (w/v) water-soluble extract of Anatolian propolis on the eukaryotic model organism Saccharomyces cerevisiae. Wild-type yeast and its isogenic deletion mutants lacking cytosolic catalase T, thioredoxin-disulfide reductase, and glutathione synthase were exposed to propolis at 0.005-0.125% (v/v) for 24 h. Cell proliferation assays demonstrated that propolis was nontoxic to wild-type cells up to 0.01% (v/v) but significantly reduced proliferation at ≥ 0.025% (v/v). Furthermore, 0.01% (v/v) propolis notably impaired cell proliferation in mutant strains relative to the wild type. FTIR spectroscopy revealed subtle biochemical alterations at 0.01% (v/v), while higher concentrations resulted in distinct spectral clustering. In parallel, cell surface integrity was preserved at 0.01% (v/v), whereas elevated doses induced pronounced structural deformations. Total oxidant status (TOS) rose significantly from 0.01% (v/v), while total antioxidant status remained stable above 0.025% (v/v), indicating a threshold beyond which oxidative stress exceeds antioxidant capacity. Lipid peroxidation occurred at ≥ 0.005% (v/v), while protein and DNA damage appeared at ≥ 0.025% (v/v). Altogether, the data demonstrate a concentration-dependent dichotomy in propolis action, reinforcing dosage as a key determinant of safety.