Antioxidant and antibacterial activities of the chemical constituents of terminalia ivorensis chev
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2008
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Abstract
Terminalia ivorensis is an indigenous plant which has found many uses in the road, housing, and carpentry industries, and is also used as phytomedicines. The bark of the plant was obtained from Kubease, a small town along the Kumasi-Konongo road in the Ashanti Region. The sample was washed, air-dried and milled. The moisture content of the milled sample was measured (10.33%). The remainder was extracted with water and ethanol, using soxhlet apparatus. The marc of the ethanol extraction was further extracted with water (herein referred to as water-after-ethanol extract). Portions of the extracts were screened for phytoconstituents and fractionated by bulk transfer methodology into groups of related polarity – chloroform fraction (i.e. acids and neutrals) and aqueous fractions (i.e. bases). The crude extracts and fractions were examined for antioxidant activities (hydrogen peroxide decomposition and Fe3+ reducing power) and also screened against Staphylococcus aureus, Escherichia coli, Pseudomonas earuginosa, and Streptococcus pneumoniae, by the diffusion method.
The crude extracts were screened for the presence of some phytoconstituents. All the three extracts of Terminalia ivorensis were found to contain saponins, steroids and triterpenoids, and anthraquinones glycosides. In addition to these phytochemicals, tannins and polyphenols, and flavonoids were found in both crude aqueous and alcoholic extracts, and anthraquinones found only in the water-after-ethanol extract. None of the extracts contained carotenoids, general glycosides, alkaloids and coumarins.
From the IR spectra of the extracts and fractions, -OH, aliphatic CH2 and CH3 groups, primary amines, amides, conjugated C=C and C=O could be deduced
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from the bark of the plant. This could confirm the presence of steroids and terpenes, polyphenols and some glycosides as indicated in the phytochemical screening.
All the extracts and their fractions (crude extracts, chloroform and aqueous fractions of the water, ethanol and water-after-ethanol extracts) of Terminalia ivorensis showed significant activities against E. coli, S. pneumoniae, S. aureus, and P. aeruginosa (MIC from 22.15 to 7937.04 μg/ml) compared to chloramphenicol (7.56 to 1881.64 μg/ml). The chloroform fraction of the water-after-ethanol extracts and the two fractions of the water extract however, did not show any activity against the test organisms.
The results from the antioxidant studies showed that the all extracts and fractions of T. ivorensis, to a large extent, have appreciable antioxidant activities, accomplished by their significant reducing power (with absorbance from 0.093 to 0.346) and decomposition of H2O2 (decreasing from 86.18 to 55.02mM). However, the crude water-after-ethanol extract and the chloroform extract of the aqueous extract however, could not decompose H2O2 (increasing from 86.18 to 588.49mM).
These antioxidant and antibacterial properties of the plant, to a large extent, are a significant factor in its usage for the management of wounds and age-related diseases (like cancer, trauma, stroke, asthma, hyperoxia, retinal damage, liver injury, and periodontis) and other bacterial-related diseases.
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A Thesis presented to the Department Of Chemistry,Kwame Nkrumah University Of Science And Technology in partial fulfilment of the requirement for the award of the Degree of Master Of Science.