Chromatographic characterisation, in vitro antioxidant and free radical scavenging activities of Garcinia kola seeds

Abstract

Garcinia kola Heckel, a tropical plant which grows in moist forest, has found wide applications in traditional medicine especially in the West and Central African sub-region. The seeds have been demonstrated to possess numerous bioactivities but research is highly limited on the link between its
fractions and the bioactivities. In this work, the methanolic extract of G. kola seeds was subjected to silica gel column chromatography into five fractions ME1 – ME5 and the free radical scavenging activities and antioxidant potentials were determined for each fraction using various in vitro models. The ME4 fraction possessed the greatest activities. It was also demonstrated that the ME4 fraction strongly inhibited nitric oxide production in lipopolysaccharide-activated macrophage U937 cells. Chromatographic fractionation and spectroscopic analysis of the ME4 fraction revealed the presence of four compounds namely garcinia biflavonoids GB1 and GB2, garcinal and garcinoic acid. These findings show that these four compounds are partly responsible for the great antioxidant potential of G. kola seeds. This gives further evidence to the nutraceutical and pharmaceutical potential of G. kola.