Genistein nanoemulsion from Saccharomyces boulardii-fermented soymilk for skin healing

This study explores an approach to wound healing by developing a nano-formulation of genistein, a soy-derived isoflavone known for its therapeutic benefits. The research utilized genistein bio-produced by the probiotic yeast Saccharomyces boulardii CNCM I-745 from fermented soybean. Initially, various soy substrates were assessed as potential sources of genistein. Fermented soymilk (24.5% (w/v)) was the optimal substrate, yielding a significantly high genistein concentration of 47.58 mg/L (P < 0.05). Genistein was extracted from fermented soymilk using methanolic extraction, followed by purification via ethyl acetate partitioning, silica gel chromatography, and preparative HPLC, yielding 5.8 mg. Its chemical identity was confirmed through HPLC, TLC and 1H NMR analyses against an authentic standard. To improve its absorption and enhance its aqueous solubility while avoiding the use of surfactants, the purified genistein (GN) was nano-encapsulated in a gum arabic-stabilized nanoemulsion (GA-NE). The optimized nanoemulsion (GA-NE3) exhibited excellent characteristics: a particle size of 23.03 ± 4.80 nm, PDI (0.286 ± 0.01), Zeta potential of -22.2 ± 4.3 mV, and a creaming index (0.67 ± 0.58). Biological evaluation confirmed the formulation’s promise. An MTT assay demonstrated high cell viability (79.5% to 97.69%) on human skin fibroblasts (BJ-1 cell line) at concentrations of 25 and 100 µg/mL, indicating low cytotoxicity. Crucially, the GN-loaded nanoemulsion enhanced wound healing in a cell migration assay, achieving high wound closure rates of 81.33% and 75.14% at 50 µg/mL and 25 µg/mL, respectively, compared to untreated BJ-1 cells after 24 h. These results establish probiotic-derived, nanoencapsulated genistein as a promising candidate for advanced wound healing treatments.