Study of sunscreen activity of aqueous, methanol and acetone extracts of leaves of Pongamia pinnata (L.) Pierre, Fabaceae

Abstract

The present research work evaluates the photoabsorptive property of different extracts of the leaves of Pongamia pinnata (L.) Pierre, Fabaceae, in the ultraviolet region (200–400 nm) and its comparison with a well-established standard sunscreen drug, p-aminobenzoic acid (PABA). The shade-dried leaves of the plant were extracted in Soxhlet apparatus using three different solvents, i.e., water, methanol and acetone. The extracts were concentrated by evaporation of the solvent and finally dried to get dry extracts. Then, 20 mg of the dry extracts was dissolved in the respective solvents and their absorption spectra were measured using UV–visible spectrophotometer. Absorbance of different concentrations of the extracts, i.e., 5, 10, 15 and 20 mg/100 ml was read at their respective wavelengths (λmax)
of maximum absorption. The aqueous and methanol extracts were found to be highly effective in the UVB and moderately effective in the UVA region. Acetone extract was found to greatly absorb exclusively in the UVA region. The known standard drug PABA showed its protective action in the UVB and UVC regions with least effectiveness in the UVA region. The extracts of the leaves of the plant under study showed extremely good absorbance throughout the UV region including UVA region. The P. pinnata extract can be used to formulate highly effective sunscreen preparations as it will enhance and effectively contribute to the UV absorbing properties of a conventional sunscreen. It will also help in broadening the UV protection ability of the sunscreens along with the greatest advantage of avoiding the adverse and undesired effects of synthetic sunscreen compounds.
Key words: Aqueous, broadening UV protection, methanol and acetone extracts, p-aminobenzoic acid, photoabsorptive property,
Pongamia pinnata, sunscreen, UV region (200–400 nm)