GC-MS analysis of leaf, stem-bark and root extracts of Alstonia boonei

Abstract

Alstonia boonei De Wild is a medicinal plant commonly found in West African and is popularly known as God's tree. The plant parts have been traditionally used as a painkiller, antimicrobial, antimalarial and antidiabetic which have also been proved scientifically. Previous studies revealed little information on phytochemcial components of A. boonei. The present work aims at investigating and comparing the chemical components of the leaf, the stem-bark and the root of the plant in order to provide sufficient baseline information for isolation work on medicinal components of the plant. Leaf, stem-bark and root extracts of A. boonei were prepared by maceration using 1:1 EtOAc/MeOH. The crude extract was successively macerated with hexane, dichloromethane (DCM) and methanol. Thin layer chromatography (TLC) by 2,2-diphenyl-1-picrylhydrazyl (DPPH) (TLC-DPPH) analysis was used to screening out DCM fraction for further analysis. Gas chromatography and mass spectroscopy studies were performed to profile phytochemical constituent of the plant. The GC-MS analysis of DCM extract of the leaf revealed ten chemical components with Eugenol as major component (54.58%); DCM extract of the stem-bark showed forty  one components with alpha-amyrin (32.25%) while DCM extract of the root revealed twenty components with 1,2-benzenedicarboxylic acid (49.2%) as major component. This study shows that the A. boonei extracts of the leaf, stem-bark and root consist of different types of compounds with few components common to two of the parts. Quantitatively, common phytochemicals decrease from leave to root. The most prominent compounds identified by GC/MS were Eugenol, benzenedicarboxylic acid and alpha-amyrin.   Key words: Phytochemicals, A. boonei, gas chromatography/mass spectroscopic studies, Eugenol