TWO ANTIOXIDANT CAFFEIC ACID DERIVATIVES FROM THE ETHYL ACETATE FRACTION OF THE METHANOL LEAF-EXTRACT OF ALSTONIA BOONEI DE WILD
Okoye NN1,2*, Okoye COB1
1.Department of Pure and Industrial Chemistry, University of Nigeria, Nsukka, Nigeria
2.Department of Chemistry, School of Sciences, Federal College of Education (Technical) Umunze, Anambra State, Nigeria
Afr. J Pharm Res Dev; Volume 8(2): 88-92 ; Nov/Dec 2016
The use of Alstonia boonei De Wild (Apocynaceae) leaves in the management of a host of ailments (such as rheumatic and muscular pains as well as hypertension and malaria) in several parts of West Africa (including Nigeria) and Asia is very common however yet to be fully validated. This study is aimed at the isolation of some phytoconstituents responsible for its anti-oxidant activity. The ethyl acetate fraction of the methanol leaf-extract of Alstonia boonei was subjected to a series of chromatographic separation giving rise to a number of sub-fractions. The chemical structures of the two compounds obtained from one of the sub-fractions were elucidated by a combination of UV, HPLC-MS, 1 D and 2 D NMR spectroscopy. The antioxidant activity of the isolated compounds was determined by DPPH free radical scavenging model. The compounds were elucidated as 5-caffeoylquinic acid (Chlorogenic acid)) and 4,5-dicaffeoylquinic acid. Both compounds showed good antioxidant activities (IC50 ˂ 25 μg/mL) on DPPH free radical scavenging model. The ethnomedicinal use of the leaves of A. boonei De Wild in the management of inflammatory diseases and other disorders associated with oxidative stress is justified by the strong antioxidant activity of the isolated compounds.
KEYWORDS: Antioxidant, Alstonia boonei, caffeic acid, Phenolic compounds
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