Pak. J. Chem. 3(2): 1-3, 2013 Full Paper ISSN (Print): 2220-2625 ISSN (Online): 2222-307X *Corresponding Author Received 30 th May 2011, Accepted 14 th March 2013 Efficacy of Erythropleum suaveolens (potrodom) and Distemonanthus benthamianus (bonsamdua) Water Extractives on the Durability of Five Selected Ghanaian Less Used Timber Species * A. Asamoah, K. Frimpong-Mensah and C. Antwi-Boasiako Kwame Nkrumah University of Science and Technology, Department of Wood Science and Technology, University Post Office Kumasi, Ghana E-mail: * asamoah38@yahoo.com ABSTRACT Conventional wood preservatives are not only toxic to target bio-deterioration organisms but also to man, other organisms and the environment. In an effort to find preservatives that are less or non- toxic to man, other organisms and the environment, efficacy of branch bark and heartwood water extracts (0.65g/ml) of Erythropleum suaveolens (potrodom) and Distemonanthus benthamianus (bonsamdua) respectively were tested on five selected less used timer species (LUS): Sterculia oblonga (ohaa), Antiaris toxicaria (kyenkyen), Canarium schweinfurthii (bediwonua), Celtis zenkeri (esa-kokoo) and Cola gigantea (watapuo) following a modified EN 252. Regardless of extract retention in selected LUS, potrodom extract improved their durability more than that of bonsamdua. Improved durability of immersed and brushed selected LUS was ranked as follows: C. gigantea > C. zenkeri > S. oblonga > A. toxicaria > C. schweinfurthii. Though extracts showed reduced efficacy with time, indications were that they could be employed to control pests in low durability woods. Keywords: Branch, eco-friendly, bio-deterioration, preservatives. 1. INTRODUCTION Conventional wood preservatives are not only toxic to target bio-deterioration organisms but also to man, other organisms and the environment especially when they take very long to bio-degrade to less or non- hazardous products when outside wood 1 . One ready source of eco-friendly preservatives is extractives from naturally durable timber species which in abundance are responsible for wood durability 3 . It appeared the efficacy of branch bark and heartwood water extracts of Erythropleum suaveolens (potrodom) and Distemonanthus benthamianus (bonsamdua) respectively had not been adequately tested in the search for eco-friendly botanical preservatives in Ghana. Thus, the aim to test by non-pressure impregnation the efficacy of branch bark and heartwood water extracts (0.65g/ml) of E. suaveolens and D. benthamianus respectively on five selected (around 50cm dbh from lat 06º 43´ N and long 01º 36´ W) less used timer species (LUS): Sterculia oblonga (ohaa), Antiaris toxicaria (kyenkyen), Canarium schweinfurthii (bediwonua), Celtis zenkeri (esa-kokoo) and Cola gigantea (watapuo) following a modified EN 252 2 . 2. MATERIALS AND METHODS Preparation of extracts: Branch bark of E. suaveolens and heartwood of D. benthamianus were air-dried, chopped into chips and milled into granules. Granules were further milled to particles of 40-60 mesh size. Extracts were removed from equal weights (200g) of particulate meals of each species in equal volumes of distilled water (5000ml) by gentle warming on hot plate at 40-60ºC 3-4 for three hours. Extract from each species was kept in a conditioning room to maintain concentration. Preparation of samples and experimental design: Freshly sawn lumber from selected LUS was air-dried for three months to 25-30 % MC 1 . True heartwood (near pith) and sapwood (near bark) samples of 60 x 25 x 12.5 mm were sawn from lumber for impregnation. Experiment was in the Complete Randomised Design (CRD) where visual durability ratings, percentage hardness loss or percentage mass loss was a single-factor (efficacy response) with its corresponding control, potrodom-extract-impregnated and bonsamdua-extract-impregnated values as levels of each single-factor (treatments). Four heartwood and four sapwood samples from each selected LUS were immersed in extracts, and the same number brushed with extracts and another left untreated as controls. Initial Data: Each sample was labelled and weighed. Hardness of sample was taken with Proceq Pilodyn [0 being no penetration (highest hardness) and 40, the deepest penetration (lowest hardness). Samples were rated visually on a scale of 0 to 4 (0 being no termite attack, 1: slight attack, 2: moderate attack, 3: severe attack and 4: failure) 2 . Initial moisture content, of samples was measured once with the Pin-type hygroscopic dielectric moisture meter. Impregnation of samples and pre-burial Data: Four sapwood or four heartwood samples were immersed in 2500ml of extracts for one week and another brushed liberally three successive times with extracts and allowed to dry for a day in-between brushing on ambient conditions. After, samples were held in a sieve for excess extract to thoroughly drain for 90 minutes and extracts retention in them determined by: {(q2-q1)/V} [5] (1)