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Due to its antioxidant and photoprotective properties, Pothomorphe umbellata is a promising candidate for use in cosmetic and pharmaceutical formulations. These properties arise from the presence of 4-nerolidylcathecol (4-NC), a polyphenolic compound isolated from P. umbellata roots. This study investigates its photostability properties, as well as the chemical and the in vitro sun protection factor (SPF) of P. umbellata root extract in a gel formulation. A high performance liquid chromatography method was used to evaluate the chemical stability using 4-NC as marker at 5, 25 and 45 degrees C for 103 days. The photostability and the sun protection factor were analyzed by ultraviolet (UV) spectophotometry using samples irradiated with UVB lamp. No significant difference of the 4-NC concentration was found in formulations stored at 5 and 25 degrees C. All samples stored at 45 degrees C, however, showed degradation of gel structure. After 2h of UVB exposure, there was no change in the absorption profile of 4-NC. The sun protection factor of P. umbellata root extract gel to final concentration of 0.1% 4-NC was not expressive (SPF=3.35+/-0.02), suggesting the predominance of its antioxidant activity.

Antioxidants such as vitamins E and C are known to play a significant role in ameliorating or preventing oxidative damage to the skin. However, to provide a satisfactory protection they must first permeate the skin, which serves as a permeation barrier. In this study we evaluated the influence of three different formulations (gel, gel–emulsion and emulsion) on the percutaneous absorption of 4-nerolidylcathecol, an antioxidant compound isolated from Pothomorphe umbellata root extracts. Also, the absorption of the isolated 4-nerolidylcathecol was compared with its absorption when dried P. umbellata root ethanolic extract was incorporated into a gel formulation. The ‘lag time method’ was employed for the analysis of the in vitro permeation data. All formulations showed satisfactory percutaneous penetration with the 4-nerolidylcathecol–gel presenting a higher rate of penetration leading to higher dry drug levels in the tissue.

Pothomorphe umbellata is a native plant widely employed in the Brazilian popular medicine. This plant has been shown to exert a potent antioxidant activity on the skin and to delay the onset and reduce the incidence of UVB-induced skin damage and photoaging. The aim of this work was to optimize the appearance, the centrifuge stability and the permeation of emulsions containing P. umbellata (0.1% 4-nerolidylchatecol). Experimental design was used to study ternary mixtures models with constraints and graphical representation by phase diagrams. The constraints reduce the possible experimental domain, and for this reason, this methodology offers the maximum information while requiring the minimum investment. The results showed that the appearance follows a linear model, and that the aqueous phase was the principal factor affecting the appearance; the centrifuge stability parameter followed a mathematic quadratic model and the interactions between factors produced the most stable emulsions; skin permeation was improved by the oil phase, following a linear model generated by data analysis. We propose as optimized P. umbellata formulation: 68.4% aqueous phase, 26.6% oil phase and 5.0% of self-emulsifying phase. This formulation displayed an acceptable compromise between factors and responses investigated.