Rapid method for isolation of plumbagin, an alternative medicine from roots of Plumbago zeylanica

Introduction: Plumbagin, a natural compound, is used as a complementary and alternative medicine. Isolation of plumbagin from Plumbago zeylanica by TLC and column chromatographic technique had various shortcomings. The objective of this work was to isolate plumbagin from roots of P. zeylanica by rapid and efficient method. Methodology: The roots of P. zeylanica were cold macerated with a mixture of chloroform/dichloromethane (1:1) and the extract was successively washed with water, saturated sodium bicarbonate and water. The concentrated washed extract was dissolved in n-hexane and recrystallized to get plumbagin. The isolated and standard plumbagin was subjected to DSC, HPTLC, UV, FTIR, H-1 and C-13 NMR and mass spectroscopy studies for assessment of chemical structure and purity. Results: The cold maceration yielded 1.2% (w/w) fine crystalline orange needle of plumbagin. It showed melting point at 78.4 degrees C, R-f value at 0.64 in n-hexane: benzene (1: 9) solvent system, UV absorption maxima at 417 nm and molecular peak [M+H](+) at 188.20 m/z. Discussion: Mass spectra and C-13 NMR confirmed the isolated compound structure which was supported by H-1 NMR. All the spectral data were comparable with that of reference standard. These results indicate that plumbagin can be isolated in a pure form effectively using cold maceration. (C) 2011 Elsevier GmbH. All rights reserved.