Soybeans isoflavone aglycone-rich extracts: Optimization by different bioprocesses and production of a purified fraction with promising wound healing property

Positive skin effects have been reported for isoflavones, mainly for their aglycone forms. In this way, the present study aimed to produce a fraction enriched in isoflavone aglycones (IA) from soybeans and to evaluate its potential for skin cells proliferation. For that, it was firstly obtained hydrolyzed extracts from defatted soybeans by different hydrolytic mechanisms, including acid, enzymatic and fermentation processes. The analysis of IA, sugars, furanic compounds, saponins and triterpenes were performed and compared for each hydrolyzed extract. The acid hydrolysis was accomplished with a classical process; however, the conditions used during enzymatic hydrolysis (EH) and fermentative process (FP) were screened by Plackett-Burman design, and subsequently optimized by Box Behnken design. The procedures were carried out using a sample corresponding to an extract obtained from 1.0 g of defatted soybeans. The optimum conditions to enhance IA content were obtained by EH using 838 units of β-glucosidase during 4.5 h at pH 6.0 and 37 °C, and by FP using 1500 mg of commercial bakery yeast (Saccharomyces cerevisiae) during 24 h at pH 7.6 and 33 °C. All hydrolyzed extracts were partitioned with ethyl acetate to obtain IA-rich fractions. The most pure and easily obtained fraction was the one from enzymatic hydrolyzed extract. This fraction was considered non-cytotoxic for keratinocytes after 24 and 48 h of treatment with concentrations between 0.1-1.0 μg of total IA/mL. Moreover, this fraction showed a proliferative effect at 0.1 μg of total IA/mL, suggesting its potential as an ingredient for skin regeneration during wound healing.