Isolation and characterization of antimicrobial components of the root of a Zambian medicinal tree terminalia mollis.
Loading...
Date
2024
Authors
Mwelwa, Gavin
Journal Title
Journal ISSN
Volume Title
Publisher
The University of Zambia
Abstract
T. mollis tree extracts have been used by THPs worldwide, in Africa and specifically in Zambia to treat various diseases in man for example urinary tract infections, sexually transmitted infections, chest infections and gastrointestinal diseases etc. T. mollis belongs to the genus Terminalia, and
the family name is Combretaceae. Most micro-organisms have developed resistance against commonly used antimicrobial drugs in modern clinical practice. This problem has necessitated the need for research into plants that have been used by THPs to treat various diseases affecting man. Plants provide a wide range of phytochemicals that inhibit micro-organism growth. Several phytochemicals have been isolated from plants which include alkaloids, steroids, tannins, saponins and flavonoids to name a few. Among the phytochemicals isolated are beta carboline alkaloids which are present in the genus Terminalia. Beta carboline alkaloids have been found to possess antimicrobial activity The genus Terminalia, has not been exhaustively investigated for the presence of antimicrobial compounds and not all species of micro-organisms have been tested against those antimicrobial compounds that have been isolated from this genus. This research intended to investigate the antimicrobial properties of the whole root of the tree species T. mollis found in Zambia with a view to isolate and characterize some of its bioactive phytochemicals. The research involved identification, collection and processing of two separate samples of the whole root of T. mollis tree, consisting the root wood and root bark from two different regions in Zambia i.e. Lusaka and Mufulira (low and high rainfall regions) and then preparing of crude extracts from the root wood and root bark. The powdered plant material from the root bark, Soxhlet extraction method and methanol as solvent were adopted for the extraction process after conducting a method and solvent optimization experiment because they produced the highest yield of crude T. mollis extract. Metabolites (alkaloids) from crude extracts were obtained by acid extraction then separating using chloroform. The separated metabolites were purified using open tubular and stop cock column chromatography, eventually 4 fractions were obtained and labelled A1, A2, B1 and B2. In vitro antimicrobial screening, using non-sterile test method for detection of the test micro-organisms, involved testing of crude extracts and the fractions obtained from chromatography on selected micro-organisms namely Staphylococcus aureus, Streptococcus pyogens, Corynebacterium diphtheriae, Escherichia coli, Salmonella typhi and Candida albicans. The stock solution of the crude extracts and fraction A1 showed inhibition of growth of all the test micro-organisms while the rest of the fractions only showed activity against Streptococcus pyogens and Corynebacterium diphtheria. MIC was determined using agar streak plate dilution method and the MIC value of the crude extracts and fraction A1 was found to be 117.18 µg/mL against Streptococcus pyogens and Corynebacterium diphtheria. Spectroscopic analysis involving 13C- and 1H- Nuclear Magnetic Resonance (NMR) indicated that all the fractions from CC had impurities. It is recommended that further purification and characterization be carried out. It is possible that the compounds contained in the fractions could be new molecules that have never been identified before.
Description
Thesis of Master of Science in Chemistry.