Desenvolvimento e estabilidade de fitocosméticos contendo extratos de Morus nigra L. (Moraceae): avaliação da atividade fotoprotetora e antioxidante

Abstract

The search for enhanced natural assets in cosmetics to prevent skin aging and other damage caused by oxidative damage is increasing as plant extracts and essential oils with remarkable pharmacological potential are observed. Morus nigra L., known as “black mulberry”, is widely used worldwide for the therapeutic value of its phenolic compounds. This work analyzed the antioxidant and photoprotective potential of plant extracts from the leaves of Morus nigra, developing phytocosmetic formulations from the incorporation of M. nigra extracts in different self-emulsifying bases. Fluid extracts (MnFE) were prepared by maceration with hydroalcoholic solution at different concentrations of ethanol 99.9% PA of 50% to 90% (v/v). After phytochemical screening, the hydroalcoholic solution was chosen at 70%, obtaining crude ethanolic extract (MnCE). The extracts were submitted to the dosage of phenols and flavonoids and to the HPLC-DAD method. The antioxidant activity was evaluated according to the method of DPPH (2,2-diphenyl-1-picryl-hydrazyl) and β-carotene and the in vitro photoprotective activity according to Mansur’s method. Subsequently they were incorporated into four types of O/W type base emulsions, totaling 36 formulations, submitted to preliminary stability. Organoleptic and physical-chemical characteristics, as well as antimicrobial activity and microbiological stability were analyzed. MnCE presented higher amounts of phenolic compounds (78.87 ± 3.29 mg GAE/g), but MnFE presented total flavonoid contents (64.58 ± 0.008 mg CE/g). MnFE showed better antioxidant activity than MnCE. Analysis by HPLC-DAD of the plant extracts identified rutin and isoquercetin. In the evaluation of the potential photoprotector, were observed an maximum absorbance of 1.438 for MnFE and of 1.351 for MnCE. In vitro SPF ranged from 4.292 ± 0.012 (MnFE 80%) and 11,17 ± 0,065 (MnFE 50%). All added benzophenone formulations showed instability, as well as samples made from the nonionic base. Antioxidant phytocosmetic (MnCE 20%), presented stability preserved and did not observe significant variations in pH analysis, viscosity and spreadability, this onde was affected by temperature. Concerning to the antioxidant activity, the samples presented an initial IC50 of 528.50 μg/ml and at the end of the study 618.31 μg/ml at room temperature. Sample stored in the refrigerator showed a considerable drop in antioxidant power. Crude extract of M. nigra and formulations presented antimicrobial activity against strains of S. aureus, S. aureus MRSA and S. choleraesuis. Challenge Test confirmed the microbiological stability of the formulations. The study confirmed the antioxidant activity of extracts, however there was no increase of photoprotective potential in the formulations. Stability of formulations based on M. nigra leaf extracts was observed, being important to complement the context of the set of other studies developed locally with this plant species.