Phytochemical investigation of Zanthoxylum Usambarense

Abstract

The genus Zanthoxylum belongs to the family Rutaceae. This Family comprises some 150 genera and over 1,600 plant species. In Kenya, the Rutaceae is represented by 28 species in 10 genera. The genus, sometimes referred to as 'prickly ashes' because of the shape of the leaves, is represented in Africa by about 40 species and in Kenya by 7 species. Zanthoxylum usambarense is widely used in traditional medicine to treat fever and malaria among other ailments. In this study, chemical investigation on the root bark and larvicidal test on the crude extract have been carried out. The crude extract of Z. usambarense exhibited larvicidal activity against the second and fourth instar larvae of Aedes aegypti with EDso values of 1.27 and 7.17 ug/ml respectively. Extraction of the root bark was done by cold percolation using dichloromethane and methanol successively. The extracts were separated by column chromatography on silica gel eluting with hexane/Cl-I-Cl- and then CH2Ch/MeOH in increasing polarity. A total of eleven compounds were isolated. The structures of the pure compounds were elucidated using NMR, ElMS and UV spectroscopy.