Annurca peel extract: from the chemical composition, through the functional activity, to the formulation and characterisation of a topical oil-in-water emulsion

<p>The aim of this study was to produce a hydro-alcoholic safe antioxidant <i>Malus pumila</i> Miller cv Annurca peel extract (APE) useful as functional ingredient in an oil-in-water emulsion. Results showed that APE contains a hydroxycinnamic acid (chlorogenic acid), flavonol glycosides (quercetin derivatives) and a dihydrochalcone, phloridzin (phloretin-2-<i>O</i>-glucoside). The isoquercitrin (quercetin-3-<i>O</i>-glucoside) content was quantified in 0.3% w/w of extract. APE showed a significant and concentration-dependent free-radical scavenging activity correlated to its polyphenols content. No cytotoxic effect was observed in primary human epidermal keratinocyte adults and dermal fibroblast cell lines. The formulative approach led to produce a stable emulsion able to load a high amount of APE, up to 6.0% w/w. The homogenous distribution of APE in the emulsion was clearly demonstrated by fluorescence microscopy analysis. The emulsion resulted able to enhance the <i>in vitro</i> release rate of APE through synthetic membranes with respect to the raw material.</p>