Organic cocoa extract -loaded surfactant-based systems intended to skin bioadhesion

Abstract

This study was to develop, characterize, and evaluate the physical-chemical stability, in vitro antioxidant activity and in vitro safety profile of liquid crystalline systems (LCS) and microemulsions (MEs) with and without organic cocoa (OC) extract. LCS stabilized by surfactant polyoxyethylene 20 cetyl ether, containing water and oleic acid were studied. LCS and MEs were characterized using polarized light microscopy, small angle X-ray scattering, rheology and in vitro bioadhesion, and were evaluated for a period of 30 days by visual aspects, centrifuge test, pH value and relative density. PLM and SAXS assays showed the presence of domains of MEs, cubic and hexagonal mesophasephases, varying the proportions of the components of the formulations; where in the addition of the extract did not change rheological behavior of the formulations. All of the formulations were stable in the period analyzed and presented higher bioadhesive strength. In vitro antioxidant activity suggests that LCS and MEs presented a high capacity to maintain the antioxidant activity of OC extract. The results showed that the incorporation of OC in LCS improved the safety profile, according to cytotoxicity assays of systems may be a promising platform to OC extract for topical application for the potential treatment of skin disorders. Keywords:Liquid crystals/evaluation/physical-chemical stability. Microemulsions/evaluation. Surfactant-based system. Organic cocoa extract. Skin bioadhesion. INTRODUCTIONSkin is routinely exposed to stressful environmental factors such as pollutants and UV radiation. These factors produce a large number of aggressive oxidants that damage all of the biological skin cell membranes (Silva et al., 2010;Binic et al., 2013;Datta et al., 2011;Dupont, Gomez, Bilodeau, 2013). Accordingly, the use of skin care products and cosmetics has been utilized to mitigate the cutaneous photoaging process (Visscher, Pan, Kitzmiller, 2013) and these products are commonly composed of plant extracts (Binic et al., 2013).A great number of plants and plant extracts are studied for their antioxidative action arising from their phenolic substructures. Phenolic compounds are composed of an aromatic ring that is linked to a hydroxyl group, which donates electrons and hydrogen atoms. As a result, these compounds are exceptional antioxidants (Silva et al., 2010;Binic et al., 2013;Reuter, Merfort, Schempp, 2010).Cocoa, the dried and fermented seeds derived from Theobroma cacao, has been consumed since 1100 B.C. by ancient civilizations such as the Mayans and Aztecs (Hurst et al., 2002). Cocoa contains high amounts of the flavonoids (−)-epicatechin (EC) and (+)-catechin, and procyanidins B2 and B1. Additionally, other polyphenols such as quercetin, isoquercitrin (quercetin 3-O-glucoside), quercetin 3-O-arabinose, hyperoside (quercetin 3-O-galactoside), naringenin, luteolin, and apigenin have also been found in cocoa in minor quantities (Sánchez-Rabaneda et al., 2003). While the natural amount B. Fonseca-Santos, E. E. Funagoshi, J. R. S. Olivei...