Determination of Total Phenolic Content of the Stem Bark of Bauhinia Variegata Linn.; an Approach to Standardization

Bauhinia variegata Linn., commonly known as ‘Camel’s foot tree or Orchid tree’, is widely distributed in most tropical countries and have been used frequently in folk medicine for varied purposes; to treat different kinds of pathologies, particularly diabetes, infections, as well as pain and inflammation owing to the presence of numerous phytochemical constituents residing in the plant. The powerful biological activities as exhibited by plant phenolics and flavonoids posed the need of determining their contents in Bauhinia variegata stem bark. The present study was aimed at estimation of total phenolics, flavonoids and tannins in the petroleum ether, ethyl acetate, methanol and aqueous extracts of the stem bark of Bauhinia variegata. The contents were determined by spectrophotometric assays by measuring the absorbance at different wavelengths. Total phenolic content were estimated by the Folin–Ciocalteu colorimetric method; the total tannin content was estimated by Folin-Denis method whereas the total flavonoid content was estimated by aluminium chloride colourimetric method. The methanol extract showed highest concentration of phenolics, flavonoids and tannins with petroleum ether extract reporting the least; ranging between 15-89 μg /mg of gallic acid equivalent, 8-135 μg/mg of (±)-catechin equivalents and 15-102 μg/mg of tannic acid equivalents respectively. The results clearly indicate that B. variegata is a rich source of phenolics, the basis of its traditional use in different systems of medicines.