ABSTRACT:
Although a variety of synthetic sunscreen formulations are available in the market, there is an unprecedental and imperative demand for safe non-comedogenic cheap and efficacious plant based topical sun screens. In this context, the present study was launched to evaluate the sunscreen potential of roots of Sri Lankan grass, Heteropogon contortus (Family: Poaceae) in vitro using a well established UV spectroscopic technique and Mansur equation. Sun Protection Factor (SPF) was determined (which is an index of sun protective activity) using methanolic extracts (concentration tested 0.05, 0.1 and 0.2 mg/mL) of the roots. Methanol soluble fraction of Dermatone® (concentration tested 0.05, 0.1 and 0.2 mg/mL), a well-known sunscreen cream, was used as the reference agent. The results showed, for the first time, that the root extract exhibited marked sun protection activity: SPF values 12.85 ± 0.87 (mean ± SEM), 12.80 ± 0.13 and 13.02 ± 0.03 respectively for 0.05, 0.1 and 0.2 mg/mL concentrations. However, this effect was not dose-dependent. Corresponding SPF values of Dermatone® were 8.21 ± 0.01, 14.00 ± 0.05 and 27.32 ± 0.12 respectively. This effect was dose-dependent. Phytochemical analysis revealed the presence of flavonoids, phenols, alkaloids, carbohydrates and proteins (based on the phytochemical tests performed). It is concluded that sun protective activity of root extract of H. contortus is mediated primarily by flavonoids and phenols via their antioxidant activity. Also, strong possibility exists to develop safe, cheap, efficacious, user friendly herbal sunscreen from roots of H. contortus.