Analysis of the Content of the Heartwood Extractives of Three Durable Nigerian Guinea Savannah Timbers.

Abstract

Resistance of most wood depend on the toxicity rather than the concentration of the heartwood extractive. However, most studies are not examining the contents of heartwood which are responsible for the resistance of most durable timbers to biological attacks. In this study, the heartwood of Prosopis africana, Burkea africana and Vitellaria paradoxa were extracted with distiled water and absolute ethanol and the extracts were subjected to phytochemical screening. The results showed that B. africana heartwood revealed 42 and 24 bioactive compounds for the ethanolic and aqueous extract. Hexadecanoic acid, methyl ester accounted for 34.82% and 17.38% of the total phyto-constituents in both ethanolic and aqueous extracts respectively. Other compounds occured in trace quantity. P. africana heartwood ethanolic (PHE) extract revealed 11 phyto-constituents while the aqueous (PHA) revealed 24 constituents. 83.36% of PHE was made up of two constitutes; 7,7-Dimethyl-1-oxo-2,3,4,5,6,7-hexahydro-1I (which accounted for 50.16% of the total constituents) and 1,4-methanophthalazine, 1,4,4a,5,6,7,8,8a-oct (33.20%) while the PHA revealed 7 compounds which were in fairly large amount. The major compound in V. paradoxa was (S)-(+)-1,2-Propanediol which accounted for 73.51% out of the 30 compounds revealed in the ethanolic heartwood extract. The aqueous heartwood extract of V. paradoxa however revealed 22 compounds with 7 of the compounds fairly large in proportion. The result showed that extraction medium had influence on the type of bioactive compounds extracted. However, some compounds were similar irrespective of the extraction medium. Extractives from these species could be isolated and utilized to increase the durability of non-durable and non-refractory wood species.