Antitermitic properties of Vitellaria paradoxa (C. F. Gaertn.) stem bark extracts onDaniellia oliveri (Rolfe) Hutch. & Dalziel AND Vitex doniana Sw. woods

Abstract

Bioactive effect of V. paradoxa stem bark n-hexane and ethyl acetate extracts on D. oliveri and V. doniana woods was investigated. Stem bark of V.  paradoxa was collected, air dried and pulverised prior to extraction. D. oliveri and V. doniana wood were purchased and processed into 10 x 2 x 2 cm dimensions. Extraction was sequentially done by dissolving 600 g of stem bark into n’ hexane and ethyl acetate, respectively and the mixtures allowed to macerate for 24 hours. Crudes were filtered and evaporated. V. paradoxa stem bark was screened for the presence of photochemical constituents. Absorption and retention of extracts in woods were calculated. Treated woods were laid out in a completely Randomized Design with 6 treatments and controls. Termite activities on test woods were recorded as incidence of attack and severity of attacked determined by percentage weight loss. Results indicate that alkaloids and cardiac glycoside were higher (0.12 % and 0.16 %) in stem bark ethyl acetate extract and lower (0.04 % and 0.07%) in stem bark n’ hexane extract. The presence of tannins and favonoids were recorded as 0.03 % and 0.01% in ethyl acetate and n’ hexane extracts while, phenol (0.11 %) and saponins (0.01%) were present in ethyl acetate, but were absent in n’ hexane extracts. V. doniana wood treated with 7.50% n’ hexane and 15 % ethyl acetate stem bark extracts were not attacked until the 7th week of the experiment. Percentage solvent absorption in woods ranged from 73.37 - 63.40 % and 81.21- 65.29 % in D. oliveri, while it was from 73.54 - 65.29 % and 92.92 - 71.43 % in V.
doniana. Extracts retension in D. oliveri wood ranged from 49.90 - 71.18 % and from 48.19 - 78.52 % whereas, it was 20.89 - 33.00 % and from 15.67 - 38.70% in V. doniana woods. Percentage weight loss in D. oliveri wood was from 52.82 - 83.82% and from 27.14 - 43.82 % in V. doniana. Termigaurd was the most effective treatment with least (7.23 - 10.40) % percentage weight loss followed by 3.75 % V. paradoxa stem bark hexane extract and 7.50 V. paradoxa stem bark ethyl acetate extract. V. paradoxa stem bark extracts are potential biocide which may be combined with other plant extracts for profitable application in wood preservation.

Keywords: Absorption, extracts, V. paradoxa, retention, phytochemical, weight loss