Extraction of vitexin and isovitexin from ficus deltoidea for skin barrier enhancement

Abstract

The understanding of plant extracts’ effect on the skin permeability barrier characteristic is important for the development of natural ingredient based cosmetic product. However, the study on the strategy of skin barrier treatment using local plants for topical use is limited. Ficus deltoidea (FD) was chosen in this study as it possesses strong antioxidant, anti–melanogenic and photo–protective activities. The objectives of this study were to optimize the extraction conditions of vitexin and isovitexin compounds from FD leaves, and to evaluate their effects on the skin hydration and skin barrier function properties in vitro and in vivo. FD extract was successfully obtained through ultrasonic–assisted extraction and optimally designed using Box–Behnken design by response surface methodology. Methanol concentration, sonication time and solvent to sample ratio were the independent variables, while yields of vitexin and isovitexin were the dependent variables. The optimal yield of FD extracts was 32.29 ± 0.08 mg/g and 35.87 ± 0.09 mg/g, for vitexin and isovitexin respectively. The optimum extraction conditions were 77.66 % methanol concentration, 20.03 minutes sonication time, and 19.88 mL/g solvent to sample ratio. The optimum extraction conditions required less solvent concentration up to 77.66 %, which is 3 % lower as compared to the preliminary experiment. The cell viability assay showed that the cell growth of human skin fibroblasts treated with FD extract was effectively increased in concentration–dependent manner, compared to untreated control and ascorbic acid. In vitro study showed that FD extract induced keratinocyte differentiation by enhancing the expression of differentiation marker genes of transglutaminase 1, caspase 14, ceramide synthase 3, involucrin, and filaggrin using real–time polymerase chain reaction. The in vivo efficacy study was conducted on 20 female subjects using tape stripping method and the study evaluated the trans–epidermal water loss, hydration, melanin, erythema and elasticity. In addition, the skin lipid analysis using high performance thin layer chromatography showed that the presence of FD extracts increased the ceramide content, and ceramide/cholesterol ratio, compared to other samples. This condition proved the ability of FD extract to enhance the skin barrier function through improvement of skin hydration and epidermal lipid integrity. Overall, the in vitro and in vivo studies have successfully demonstrated the efficacy of FD extracts in the formation of an effective moisture barrier which includes: corneocyte strengthening, lipid processing and natural moisturizing factor generation.