Activation of polyphenolic compounds as new ingredients for sustainable cosmetic formulation

This study used fruit peel, an abundant source of antioxidant molecules, to develop a sustainable approach for obtaining compounds with improved bioavailability at the skin level. Ultrasound-assisted extraction (UAE) and enzymatic fermentation (Saccharomyces Cerevisiae) were combined to promote the bioconversion of glycosylated molecules found in the Wonderful pomegranate peel into their aglyconic forms. To monitor the conversion of glycosylated molecules in their aglycone form, by high-performance liquid chromatography coupled with a diode array detector (HPLC-DAD), samples were analyzed at three different time points: before the start of the fermentation process (D0), after one day (D1), and after fourteen days of fermentation (D14). The results allowed the identification and monitoring of the signal loss related to glycosylated molecules (cyanidin 3-glucoside and pelargonidin 3-glucoside), used as standards over time. The antioxidant capacity was evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), and the ferric-reducing antioxidant power assays. Total phenol content (Folin-Ciocalteu assay), cell viability, cytotoxicity, and antioxidant capacity on Human Gingival Fibroblasts (HGFs) were also evaluated. An increase in the total phenol content (TPC) was detected in the fermented extracts at D1 (17.31 μmol GAE/g) and D14 (11.90 μmol GAE/g), differently than the unfermented ones at D0. The antioxidant capacity was higher in D1 and D14 than in D0 samples. The viability test revealed that HGFs tolerated all tested doses, as cellular viability consistently exceeded 80 %. A statistical reduction in cytotoxicity and an increased cell antioxidant capability when treated with fermented extracts were also detected. A face cosmetic emulsion containing a fermented extract was tested for in vivo efficacy of forty volunteers with superficial and deep skin hydration, transepidermal water loss (TEWL), redness, texture, and wrinkles. The treatment resulted in an increase in both superficial and deep hydration, a reduction in TEWL, a decrease in skin redness, enhanced texture uniformity, and a reduction in the wrinkle index.