Contents lists available at ScienceDirect Industrial Crops & Products journal homepage: www.elsevier.com/locate/indcrop Inhibition of fungi with wood extractives and natural durability of five Cameroonian wood species Jean-Bosco Saha Tchinda a,b, ⁎ , Maurice Kor Ndikontar b , André Désiré Fouda Belinga b,e , Steeve Mounguengui c , Jacques Michel Njankouo d , Stéphane Durmaçay a , Philippe Gerardin a a Laboratoire d’Etudes et de Recherche sur le Matériau Bois (LERMAB), EA 4370 USC INRA, Université de Lorraine, Faculté des Sciences et Technologies, BP 70239, 54506 Vandoeuvre lès Nancy, France b Macromolecular Chemistry Unit, Applied Chemistry Laboratory, University of Yaoundé 1, Faculty of Science, P.O. Box 812, Yaoundé, Cameroon c Institut de Recherches en Ecologie Tropicale, BP 13354 Libreville, Gabon d Department of Civil Engineering, National Advanced School of Engineering, P.O. Box 8390, Yaounde, Cameroon e Centre de Recherches en Plantes Médicinales et Médecine Traditionnelle, Institut de Recherches Médicales et d’Etudes des Plantes Médicinales (IMPM), Ministère de la Recherche Scientifique et de l’Innovation, BP 6063 Yaoundé, Cameroon ARTICLE INFO Keywords: Cameroonian wood species Extractives Natural durability Inhibition of fungi ABSTRACT The natural durability of five Cameroonians wood samples was evaluated using the European standard EN 350-1 with a slight modification. The capacity of extracts to inhibit the fungal growth was evaluated at different concentrations with propiconazole (a commercial fungicide for wood) as standard. Scanning Electron Microscopy (SEM) of wood blocks was carried out before and after extraction in different solvents. Unextracted and extracted wood blocks were exposed to fungal attack, with beech as a reference wood. Results showed that mass losses of non-extracted samples ranged from 0.1 to 59% and those of extracted samples from 3% to 40%. Before extraction, all wood samples under study were classified as very resistant to fungi attack (class 1) with respect to the standard. After extraction, some of the wood samples became vulnerable to fungal attack. Movingui, padouk, and tali became less resistant to fungi attack (class 3). The SEM of wood revealed that the extractives were removed from the fibres. The effect of extractives on fungal growth showed that extracts weakly inhibited fungal growth up to concentrations of 250 μg/mL but extracts of tali and movingui totally inhibited fungal growth at a concentration of 500 μg/mL. 1. Introduction Wood plays an important role in human activity. It is used as ma- terial for products, building construction, etc. Wood can be used inside or outside, as packaging, for plywood and as panels. The wood of Triplochiton scleroxylon (Ayous) was used in the construction of parts of the celling of Roissy Airport (Vernay, 2005). For these applications, wood must possess a good natural durability against insect and fungal attacks, as well as a good dimensional stability and weather resistance (Ali et al., 2011). Some tropical woods have very good natural dur- ability against wood destructive agents. These species are most often exported to Europe, Asia and the United States of America. Recently, Cameroon passed a law that banned the exportation of certain wood samples, thereby favoring the local processing of logs. This local transformation leads to the production of a huge amount of wood waste (sawdust, bark and board residue) that is usually burnt or abandoned but which could be valorized (Saha Tchinda, 2015). In 2006, this transformation generated 245 million m 3 of waste, about 1.20 million tonnes. In many industrialized countries, such waste is valorized in the production of particle board, composite materials and energy, thus this waste represents a real economic potential. To optimize the use of waste from timber exploitation, the valorization of wood extractives can be envisaged without stifling other uses; extraction could be carried out prior to other transformation processes. Extractives are low mole- cular weight substances located in the porous structure of wood. They are generally lipophilic or hydrophilic secondary metabolites i.e. compounds that are not essential for the growth of the tree. The content and composition of extractives vary with wood samples, the part of the tree, its age, geographical site of harvest, season of the harvest and storage time and conditions. Extractives are responsible for wood https://doi.org/10.1016/j.indcrop.2018.06.078 Received 8 March 2018; Received in revised form 10 June 2018; Accepted 23 June 2018 ⁎ Corresponding author at: Laboratoire d’Etudes et de Recherche sur le Matériau Bois (LERMAB), EA 4370 USC INRA, Université de Lorraine, Faculté des Sciences et Technologies, BP 70239, 54506 Vandoeuvre lès Nancy, France and MacromolecurChemistry Unit, Applied Chemistry Laboratory, University of Yaounde 1, Faculty of Science, Department of Inorganic Chemistry, P.O Box 812, Yaounde, Cameroon. E-mail address: saha_jb@yahoo.fr (J.-B. Saha Tchinda). Industrial Crops & Products 123 (2018) 183–191 0926-6690/ © 2018 Elsevier B.V. All rights reserved. T