Wood is mainly made up of cellulose, hemicelluloses, lignin polymers and other organic and inorganic substances, making it susceptible to deteriorate by various biological agents. Tectona grandis L.f. (Teak) is a timber species with high resistance to biological deterioration, valued for its durability, beauty, and mechanical resistance. The purpose of this work was to evaluate the antifungal activity of crude extracts from teak on various fungi that cause wood deterioration. For this, Teak heartwood was obtained, then fragmented and pulverized until obtaining a flour which was used for compounds extraction using the Soxhlet technique coupled to a rotary evaporator through solvents of increasing polarity (hexane, dichloromethane, tetrahydrofuran, and acetone). The extracts obtained were tested against fungal organisms collected in the field, and the LC 50 was determined using teak crude extracts on Artemia salina as a biological model. The results obtained showed that a high flour yield was obtained with hexane (0.951 g), followed by tetrahydrofuran (0.446 g), dichloromethane (0.348 g), and acetone (0.152 g). By using nine fungal organisms that predominantly correspond to the genus Aspergillus, the extractable compounds were tested, inhibiting 25% of mycelial growth with tetrahydrofuran (T. versicolor), and 40.9% with dichloromethane (G. trabeum). Likewise, the biological model of A. salina showed an LC 50 of 84.9 μg/mL with hexane, 43.3 μg/mL with dichloromethane, 59.6 μg/mL with tetrahydrofuran, and 54.7 μg/mL with acetone. For this reason, it is concluded that Teak wood contains many extractable compounds in relation to its weight, besides having antimicrobial activity when extracted through polar compounds such as dichloromethane and tetrahydrofuran.

Wood is an organic material that is a source of carbon of organisms called Wood-decay fungi, and to preserve the wood, various toxic compounds to man and the environment have been used. To analyze the effect of N,N-Dimethylhexadecylamine (DMHDA) on wood attacked by the rotting fungus Trametes versicolor L. We used an in vitro system to expose the fungus T. versicolor to different concentrations of the DMHDA (50, 150 and 450 µM). We quantified the diameter of mycelial growth and laccase activity, also, under these experimental conditions we studied morphological details of the organisms using different scanning equipment including scanning electron microscopy. The growth of T. versicolor exposed to DMHDA for 60 days, showed a concentration-dependent dose behavior, also, the electron microscopy analysis revealed that the morphology and mycelial density was affected by the DMHDA, showing a formation of atypical morphological and thickener folds. Finally, the pieces of wood treated with DMHDA and exposed to the fungus had a lower mass loss, after a period of 60 days of exposure, the values obtained were 0.7, 1.0 and 0.5 g of mass lost for the control, LoC and LoDMHDA treatments respectively. Wood-rot fungi have represented economic losses worldwide, the strategies used have been supported by toxic compounds for the environment. The DMHDA both in the Petri dish system and as a wood preservative was shown to significantly inhibit the growth of T. versicolor.

Introduction: Wood is susceptible to be used as a carbon source by fungal species damaging the wood. Its durability has been categorized according to its weight loss, without taking into account the decrease in the inherent physicochemical and mechanical properties. Objective: To evaluate how how weight loss affects the physicochemical and mechanical properties of Pinus pseudostrobus Lindl. wood exposed to brown-rot fungi Gloeophyllum trabeum (Pers.) Murrill. Materials and methods: Sawn timber pieces of P. pseudostrobus were inoculated with 50 mL of G. trabeum (106 UFC∙mL-1). Periodically (zero, three, six and nine months) and with the help of a universal testing machine, parallel compression (PC), static bending (SB) and perpendicular compression to the grain (CPG) were evaluated, and holocellulose, cellulose and lignin were quantified. Results and discussion: After nine months of interaction with G. trabeum, the pieces of wood were resistant to degradation, taking into account only weight loss. However, the chemical-mechanical properties evaluated showed that the fungus produced thinning and rupture of the tissue cells causing significant decrease in SB (100 to 56 N∙mm-2) and CPG (42.2 to 20.2 N∙mm-2), which reduced its resistance to mechanical stress. Conclusions: Wood exposed to fungal degradation is significantly affected in its mechanical properties, disqualifying it for construction. The damage is not reflected in the aesthetics of the material, which is surprising, since the common user of pine wood would not be able to notice the problem.

Introducción: La madera es propensa a ser utilizada como fuente de carbono por especies de hongos que la dañan. La durabilidad de la madera ha sido categorizada de acuerdo con la pérdida de peso sin considerar la disminución de las propiedades fisicoquímicas y mecánicas inherentes. Objetivo: Evaluar cómo afecta la pérdida de peso a las propiedades fisicoquímicas y mecánicas de la madera de Pinus pseudostrobus Lindl. expuesta al hongo de pudrición café Gloeophyllum trabeum (Pers.) Murrill. Materiales y métodos: Piezas de madera aserrada de P. pseudostrobus se inocularon con 50 mL de G. trabeum (10 6 UFC∙mL -1 ). Periódicamente (cero, tres, seis y nueve meses), y con la ayuda de una máquina universal de ensayo, se analizó la compresión paralela, la flexión estática (FE) y la compresión perpendicular a la fibra (CPF); además, se cuantificó la holocelulosa, celulosa y lignina. Resultados y discusión: Después de nueve meses de interacción con G. trabeum, las piezas de madera fueron resistentes a la degradación, considerando únicamente la pérdida de peso. No obstante, las propiedades químico-mecánicas mostraron que el hongo produjo adelgazamiento y ruptura de las células del tejido ocasionando disminución significativa de FE (100 a 56 N∙mm -2 ) y CPF (42.2 a 20.2 N∙mm -2 ), lo cual redujo su resistencia a los esfuerzos mecánicos. Conclusiones: La madera expuesta a la degradación por hongos está afectada significativamente en sus propiedades mecánicas, inhabilitándola para la construcción. Los daños no se reflejan en la estética del material, lo cual es alarmante, ya que el usuario común de la madera de pino no podría notar el problema.