Chromatographic Finger Printing and Quantification of Gallic Acid in Amla (Emblica Officinalis Gaertn.), Palasa (Butea Monosperma Taub.) and Amalaki Rasayana

Abstract

Gallic acid (3,4, is a naturally occurring hydrolysable tannin and a potent antioxidant molecule. In Ayurveda, Rasayana therapy has been proposed as a remedy for ageing and associated ailments. The present study aims to analyse the gallic acid (GA) content in an important Rasayana used in Ayurveda viz., Amalaki Rasayana. High-Performance Thin-Layer Chromatography (HPTLC) method was carried out to delineate the phytoconstituents present in the methanolic extract of shade-dried powdered berries of Amla, the stem of Palasa and Amalaki Rasayana. The TLC plate developed in mobile phase toluene: ethyl acetate: formic acid (6:5:1v/v) had revealed 10, 6 and 5 phytoconstituents respectively for Palasa, Amla and Amalaki Rasayana. Densitometric scanning of GA had shown the absorption spectra λ max at 276 nm and polynomial regression analysis had revealed a good linearity response (r = 1.0000) in the concentration ranges of 1.44 -15.84 µg/spot and mean content of GA in raw berries of Amla was estimated as 0.364% of its dry weight and that of processed Amla (i.e., Amalaki Rasayana) as 0.415%. The chromatographic data could fail to produce any detectable amount of GA in the stem of Palasa. The scaling up of the content of GA (5.33%) in thermal processing is suggestive that heat might have induced degradation of the polyphenols (viz., the polymers of ellagic acid, or gallic and ellagic acids) of the flesh of Amla berries, due to a combination of leaching, oxidation by polyphenol oxidase, enzymatic action and isomerization.