Hibiscus acid extract, biorefinery process and ex vivo scientific evidence as natural skin renewal

α-Hydroxy acids (AHAs) are widely used in numerous cosmetic formulations in order to achieve a variety of beneficial effects for the skin: antioxidant, skin whitening, skin peeling [1 – 4]. The most prominent representatives in this class of compounds are glycolic acid and lactic acid. It is reported that 15 – 30% of the hibiscus (Hibiscus sabdariffa L.) flower is made up of organic acids, including citric, malic, tartaric acids and (+)-allo-hydroxycitric acid lactone – i.e. hibiscus acid which is a specific marker of this plant specie [5]. Through a process including industrial column chromatography, a standardized extract with 45 – 65% organic acids has been obtained as one of the valuable fractions for the nutraceutical and cosmetic market. No evidence exist on the skin peeling and skin depigmentant activity for the hibiscus flower extract. Ex vivo studies on reconstructed human epidermal were conducted and non cytotoxic concentrations were used. In comparison to lactic acid and glycolic acid, hibiscus acid extract has shown a best exfoliant activity at the same different concentrations tested ranging from 0.25% to 1%. The AHAs of hibiscus extract could act as a chelating agent in the epidermis, which may reduce Ca²⁺ concentration at the cellular junctions and thus cell adhesion [6]. Indeed, cadherin molecules mediate calcium dependent cell-cell adhesion. The extracellular domain of C-cadherin features five repeats with calcium ions binding at linker regions between repeats. The domain adopts an elastic ordered shape in presence of calcium ions. A disordered conformation is achieved upon removal of calcium [7]. Finally, the biorefinery approach allowed to identify current fractions still recoverable. Due to the higher activity of the hibiscus acid extract, these results pave the way to switch the synthetic solution by a natural one.

Keywords: Biorefinery, AHA, hibiscus, exfoliant.

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