Evaluation of in vitro sun screening activity of Solanum violaceum (Thiththa thibbatu) leaf extract

Abstract

In this study, the total phenolic content (TPC), total flavonoid content (TFC) and in vitro sun screening activity of 80% aqueous methanol extract of Solanum violaceum (Thiththa tibbatu) leaves were evaluated. TPC and TFC were determined by colorimetric methods using Folin-Ciocalteu reagent and aluminium chloride, respectively. Sun protection factor (SPF) was determined according to the Mansur equation using UV absorption data in the range of 290-320 nm (at 5 min interval) taken in methanol. The methanol extract of S. violaceum leaves was subjected to phytochemical screening for common phytochemicals and the results revealed the presence of phenolic compounds, flavonoids, saponins, carbohydrates and alkaloids. It was found to have a total phenolic and total flavonoid contents of 2781.168 ± 196.782 mg GAE/100 g DW, and 1151.048 ± 36.321 mg CAE/100 g DW, respectively. A concentration series of 1.0, 0.5, 0.2. 0.1 and 0.05 mg/ml solutions of S. violaceum extract was prepared in methanol along with the same concentration series of the reference Dermatone®. The SPF values were determined at all these concentrations and it was found that at 1.0 mg/ml concentration SPF value was 40 which is significantly higher than that of the reference Dermatone® (35) at the same concentration. It also has a SPF value of ca 12 at 0.2 mg/ml concentration which is close to the threshold value (15) of efficient sunscreen agents at that concentration. Finding of a significant sun screening activity in S. violaceum leave extract would open an avenue for the preparation of herbal sunscreens with little or no side effects.