PHYTOCHEMICAL, ANTIHYPERTENSIVE AND ANTIMICROBIAL STUDIES ON THE STEM BARK EXTRACT OF STEREOSPERMUM KUNTHIANUM CHAM (BIGNONIACEAE)

PHYTOCHEMICAL, ANTIHYPERTENSIVE AND ANTIMICROBIAL STUDIES ON THE STEM BARK EXTRACT OF STEREOSPERMUM KUNTHIANUM CHAM (BIGNONIACEAE)

Abstract:

Stereospermum kunthianum (Family: Bignoniaceae) plant is used in Hausa ethnomedicine in treating bronchitis, veneral diseases, diarrheoa and dysentery. It is also used in the treatment of ulcers, leprosy, skin eruptions, respiratory ailments, abortifacient, antihypertensive and gastritis. The plant is common in Northern Nigeria where it is used as abortifacient and as antihypertensive agent. Preliminary phytochemical investigation of methanolic extract of the stem bark of Stereospermum, kunthianum revealed the presence of sterol/triterpenes, coumarin, saponins, flavonoids, steroids, tannins and carbohydrates. Extensive phytochemical investigations using silica gel column chromatography, gel filtration and preparative thin layer chromatography led to the isolation of β – sitosterol from Hexane fraction, ipolamiide (an Iridoid glyciside) and a flavonoid diglycoside Quercetin 3-O-β-D-glycopyranosyl (1→6)-α-rhamnoside (rutin) from the acetone fraction. The structures of these compounds were elucidated using UV, IR and 1D and 2D NMR. The antihypertensive property was evaluated by studying the effect of the acetone fraction on the cat blood pressure. The acetone fraction, dose dependently decreased cat blood pressure and the decrease in the blood pressure was not blocked by atropine.This implied that the action of acetone was not via muscarinic receptors.The paper discs diffusion method was used to determine the antimicrobial activities of the stem bark methanol extract, hexane, ethyl acetetae and acetone fractions using the following clinical isolates, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Salmonella typhi. as the test microorganisms. The results of the antimicrobial study obtained indicated that the extract of the Stereospermum kunthianum inhibited the growth of the microorganisms within the range of 10 – 22mm diameter zone of inhibitions. This, therefore, shows that viii the extract and fractions contains substance(s) that inhibit the growth of some microorganisms. Ipolamiide isolated from acetone fraction was found to be active against Staphylococcus aureus, Streptococcus pneumoniae, Klebsiella pneumoneae, Escherichia coli, Salmonella typhi and Candida ikrusei, with zones of inhibition ranging from 21 – 29 mm against all the susceptible microorganisms. The results of this study has added compounds ipolamiide and rutin to data base of the family of Bignoniaceae, expanded our knowledge on phytochemistry of Stereospermum kunthianum and provided scientific rationale for the ethnomedicinal uses of the plant.

PHYTOCHEMICAL, ANTIHYPERTENSIVE AND ANTIMICROBIAL STUDIES ON THE STEM BARK EXTRACT OF STEREOSPERMUM KUNTHIANUM CHAM (BIGNONIACEAE)