A validated HPTLC method for the simultaneous determination of seasonal alterations of two antihypertensive monoterpenoid indole alkaloids in Rauvolfia species from northern India

Abstract

The genus Rauvolfia belongs to the family Apocyanaceae, and is native to the tropical countries of the world. Six species of Rauvolfia have been reported from India, however, only two species viz. R. serpentina and R. tetraphylla grow in the upper Gangetic plains. The monoterpenoid indole alkaloids reserpine and ajmalicine are the major phytochemicals reported from the roots of the above plants and are well known for their potential antihypertensive activity. Presently, R. serpentina has become critically endangered due to its overexploitation. Therefore, this study was designed to develop a validated High Performance Thin Layer Chromatographic densitometric method for determination of reserpine and ajmalicine in R. serpentina and R. tetraphylla in different seasons. Plant materials were collected in March, June, September and December to determine the optimal harvesting time. The densitometric method was validated in terms of instrument precision, range, linearity, specificity, limit of detection and limit of quantitation. Reproducibility of the peak of reserpine and ajmalicine was achieved at Rf 0.56, and 0.79 respectively using optimised mobile phase toluene– ethyl acetate-diethyl amine (7:2:0.6 v/v/v). Our study concluded that maximum level of ajmalicine was found in March while that of reserpine was observed in September. Harvesting of R. tetraphylla at the optimal season may reduce the overexploitation of the endangered species R. serpentina.