Antifungal Activity of Crude Extracts of Tectona grandis L.f. against Wood Decay Fungi

Abstract

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.

Repellent and Insecticidal Activity of Naphthoquinones from the Heartwood of Tectona grandis on Incisitermes marginipennis (Latreille)

“…The natural durability of wood is understood as the resistance that some species present against environmental deterioration, and is attributed to the presence of extractive compounds [41], and in this sense, for low-durability wood, a wide variety of organic and inorganic compounds are used in the preservation industry to control termites and other xylophagous organisms, using physical (Barriers toxic and nontoxic, also treatments employing heat, electricity, freezing, or microwave), chemical (copper/ chromium/arsenical salts; copper/azoles/organics; coppers/azoles/organics/boron; cypermethrin; pentachlorophenol; arsenic/copper/ammonia; chromium/zinc/chlorine) and biological methods (bacterial toxins, mycotoxins, essentials oils and more) [42,43]. The present work is shown as the only one where naphthoquinone compounds have been tested on low-durability wood, finding that wood preserved with deoxylapachol, tecomaquinone-I, and lapachol showed mortality percentages of ≥90 in drywood termites.…”