Phytochemical, Anthelmintic And Antimicrobial Investigation Of Hagenia Abyssinica (bruce) Gmelin

Abstract

Hagenia abyssinica (Bruce) Gmelin is a flowering plant that is widespread in the afromontane regions of Central and Eastern Africa. It is an important medicinal plant that societies relied on for generations for combating various ailments. Its inflorescence, for example, is used traditionally as an anthelmintic. Its roots are cooked in soup for treatment of malaria and the pounded bark is used for treatment of diarrhea. Besides being a source of medicine, Hagenia has been utilized for various other purposes such as construction, furniture, fuel and soil fertility management. As a result of its enormous significance, H abyssinica is at risk of becoming an endangered tree species due to overexploitation. The objective ofthis study was to carry out phytochemical/investigation of its chemical constituents and screen it for in vitro anthelmintic and antimicrobial activities. The plant material was collected from South Kinangop, Nyandarua county in September, 2009. Phytochemical tests showed that the plant powders contained alkaloids, tannins, saponins and cardiac glycosides. The plant extraction was done by maceration and percolation using petroleum ether, chloroform, dichloromethane / methanol mixture and methanol. The petroleum ether and chloroform extracts were subjected to open column chromatography using solvents of varying polarity as the mobile phase. Thin layer chromatography was used to monitor the fractions. Two crystalline compounds were isolated from the chloroform extract and subjected to spectroscopic analysis. One of the compounds was identified as sitosterol. The second one was obtained in insufficient quantities and thus its structure could not be elucidated. The in vitro anthelmintic activities of crude extracts of the stem bark and flowers were investigated. Screening for anthelmintic activity was carried out using Panagrellus redivivus model whereby the methanol and dichloromethane/ methanol extracts exhibited activity. Further tests were carried out on the stem bark methanol extract. These were the whole worm and the cut worm assays using Caenorhabditis elegans species. In these assays, the activity of the methanol extract was compared to levamisole to show the percentage of worms alive after incubation at room temperature for 24 hours for whole worm assay; and the time in minutes taken to paralysis in cut worm assay. The extract showed significant but weaker activity than levamisole. Some of the plant extracts were screened for both antibacterial and antifungal activities using agar diffusion method. Petroleum ether and dichloromethane/ methanol extracts showed activity against: Staphylococcus aureus, Escherichia coli and Bacillus subtilis. The respective diameters of zones of inhibition were 17, 16 and 16 mm for petroleum ether extract; and 19, 20 and 18 mm for dichloromethane/ methanol extract, while that of positive control was 20 mm for all the bacterial microorganisms. Chloroform extract at the same concentration only exhibited weak activity against Bacillus subtilis and the methanol extract did not exhibit any activity. All the Hagenia extracts tested lacked any antifungal activity at a concentration of 50 mg/ml. The present study shows there may be a scientific basis for the traditional use of Hagenia abyssinica as an anthelmintic and also for treatment of diarrhea and livestock diseases caused by bacteria.