Phytochemical Investigation and antioxidant activities of fractions of Erythrina abyssinica stem bark






Reactive oxygen species (ROS) are chemically reactive molecules containing oxygen. These ROS react with biological molecules causing structural and functional damage. Oxidative damage accumulates in human tissues with age and can causally contribute to a number of degenerative diseases, such as heart disease and cancer. Of particular concern is the generation of these ROS moieties during malarial infection. Antioxidants, both enzymatic and non-enzymatic, limit oxidative damage to biological molecules by various mechanisms.


The phytochemical Investigation of Erythrina abyssinica has led to isolation of mainly flavonoids among other classes of compounds. Flavonoids display a wide range of biological and pharmacological activities such as antiplasmodial activities most of which could be attributed to their radical scavenging activities (RSA). There is speculation that the antiplasmodial activities of extracts and pure compounds could be attributed to the ability of the phenolic compounds in the extract to wipe out ROS generated in different stages of malaria infection.


In this study the RSA of purified extracts the will be compared with that of pure compounds tested in earlier studies in order to establish whether there is reduction in RSA with purification as is the case with antiplasmodial activity.


The root bark was dried, ground and extracted thrice using CH2Cl2:MeOH (1:1 ratio) by cold percolation for 72 hours at room temperature. The impurities were removed by filtration and the extract concentrated using a rotary evaporator. This extract was then adsorbed onto silica gel and then loaded into a column containing silica gel. The extract was subjected to gravity column chromatography on silica gel eluting with mixtures of n-hexane/ethyl acetate in increasing polarity. Further purification of the fractions using chromatography on silica gel, analytical Thin Layer Chromatography (TLC) and crystallization led to the isolation of one compound from this extract. The structure of this compound was elucidated using 1H NMR and13C NMR.


The crude extract and fractions obtained from the initial column were subjected to RSA towards DPPH and quercetin as standard.


Key Words: Erythrina abyssinica, Stem bark, Antioxidant activity, Fractions, Phytochemistry

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