Bioguided isolation of an antioxidant compound from <i>Combretum racemosum</i> P.Beav leaf

Abstract

Free radicals are known to cause damage to the body cells leading to many diseases. These cells can be protected from such deleterious effects by antioxidants; therefore, plant derived antioxidants are of global interest. Combretum racemosum have been used traditionally in the treatment of ulcers, cancers and infections. Current studies investigated the antioxidant activities of this plant extract and its fractions. The antioxidant activity of the crude extract was determined by Ferric Reducing Power Assay, DPPH free radical scavenging assay, Total Phenolic and Total Flavonoid Content methods. Bioguided column chromatographic separation was carried using DPPH free radical scavenging assay to assess activity of fractions. A bioactive compound was isolated and characterized by application of Spectroscopic techniques (ESI-MS, HRMS, 1D and 2D NMR). Bioactivity of the crude extract showed that Combretum racemosum has good antioxidant activity which is comparable to the reference antioxidant (catechin). Bioactivity guided fractionation using DPPH method led to the isolation of 2-(3,4-dihydroxyphenyl)-3,4-dihydro-2H-chromene-3,5,7-triol as an active principle from the extract. This study suggests that there is a scientific basis for the application of C. racemosum extract in the management of diseases that are associated with cell damage caused by free radicals.

Keywords: Combretum racemosum, DPPH, FRAP, Antioxidant, 2-(3,4-dihydroxyphenyl)-3,4-dihydro-2Hchromene- 3,5,7-triol.