Evaluation of Partially Purified Fractions of Crude Extracts of the Leaves of Morinda lucida (Benth.) and Datura stramonium (L.) for Suppression of Wood Damage by Subterranean Termites

Abstract

Ethanol extracts of Morinda lucida and Datura stramonium leaves were partitioned successively into petroleum ether, chloroform, ethyl acetate and methanol fractions. Each fraction was tested as wood preservative in-vivo at three different concentrations: 0.5%, 1.0% and 1.5%w/v. Basudin®, an organophosphate was used as standard. The extracts were applied on Triplochiton schleroxylon, a highly susceptible wood to termite infestation. The treated wood samples were exposed to termites for a period of twelve weeks. Observation was carried out weekly for signs of termite infestation. Weight loss in wood samples that were treated with fractions of D. stramonium leaf extract ranged from 8.20% - 13.50% in petroleum ether fraction, 9.35%-19.99% in chloroform fraction, 6.15% and 10.89% in ethyl acetate fraction and 10.81%-20.27% in methanol fraction. Petroleum ether, chloroform, ethyl acetate and methanol soluble fractions of M. lucida gave a weight loss range of 5.25%- 9.50%, 6.28%-11.50%, 4.89%-6.70% and 8.50%-20.27% respectively. Ethyl acetate soluble fraction of the two plants appeared to be more potent in suppressing wood damage. Ethyl acetate soluble fraction of M. lucida was the most effective in damage reduction. Methanol fraction was the least effective with the highest recorded weight loss at all the treatment levels. The weight loss recorded at all treatment levels with fractions of M. lucida was lower compared to the result obtained in treatment with D. stramonium leaf fractions. The phytochemical screening, 1H NMR and 13C NMR suggest anthraquinone and scopoletin as the major components of ethyl acetate soluble fraction of M. lucida. This study reveals that the two plants have components that are potential wood preservatives.