Photoprotective Effect of the Hydroalcoholic Extract from Red and Black Peruvian Varieties of <i>Phaseolus vulgaris</i> L.

Abstract

Introduction: Ultraviolet radiation can be harmful to the skin and can create serious problems when a protective substance or equipment is not used regularly, for this reason the present study set out to evaluate the photoprotective effect of the hydroalcoholic extracts of the integument of the red and black varieties of pop beans (Phaseolus vulgaris). Materials and Method: The extracts were obtained by macerating the tegument of the two varieties of pop beans, black and red, in an ethanol/water (80:20) solution. The thin-layer chromatographic method was used to observe anti-tyrosinase activity, using the 0.05% kojic acid standard as a positive control. The photoprotective effect was evaluated in female mice of seven-week-old, Mus musculus Balb/c, with shaved back and exposed to UV-C radiation for 30 minutes once a day for thirty days to induce photo-damage in the skin. The treatments consisted in the application of extracts at 2% and 5% W/V in gel on the shaved area. Only the gel formulation, sunscreen or no treatment at all was used for the control group. Acute photodamage was quantified using the Draize scale, measuring the degree of erythema and edema; and the degree of photoaging using the Glogau scale at 7 days and 30 days. Results: It was found that the ethanolic extracts of the integument of both varieties of Phaseolus vulgaris, red and black, are practically non-toxic in mice by oral and dermal routes at a limit dose of 5000 mg/kg. The anti-tyrosinase effect at a qualitative level, evaluated by thin layer chromatography, showed the black variety were more active than the red one and both can be compared to the activity of the kojic acid. The two extracts of the two varieties showed photoprotective effect, however the extracts in 5% gel to a greater degree. Conclusions: It was concluded that the hydroalcoholic extract of the pop black beans tegument at 5% in gel has photoprotective effect.