Improving Fungal Decay Resistance of Less Durable Sapwood by Impregnation with Scots Pine Knotwood and Black Locust Heartwood Hydrophilic Extractives with Antifungal or Antioxidant Properties

Abstract

Research Highlights: The antifungal assay confirmed that knotwood extractives of Scots pine inhibit the growth of wood decay fungi. Heartwood extracts of black locust were found to be much stronger free radical scavengers than the extracts of Scots pine. The extracts were deposited in the lumina and on the wall surface of cells in the impregnated sapwood. Impregnation of the sapwood blocks with Scots pine and black locust extracts reduced the fungal decay of wood. Objectives: Hydrophilic extracts of Scots pine knotwood and black locust heartwood were chemically analyzed, tested for antifungal and antioxidant properties and used for impregnation of beech and Scots pine sapwood. Materials and Methods: Scots pine knotwood and black locust heartwood were extracted, and obtained hydrophilic extractives were chemically analyzed. Extracts were analyzed for antifungal properties with the in vitro well-diffusion method. The free radical scavenging activity of wood extracts was measured colorimetrically. The retention of the extracts in the impregnated sapwood blocks was evaluated with microscopy and gravimetry. A decay test was performed with the mini block test. Results: Almost half of both Scots pine knotwood and black locust heartwood hydrophilic extracts obtained were described by phenolic compounds. The extracts were deposited in the lumina of cells and on the cell wall surface. Extractives of Scots pine knotwood had good inhibitory properties against white- and brown-rot fungi. On the other hand, extractives of black locust heartwood were found to be good radical scavengers, better than knotwood extractives of Scots pine. The extracts of Scots pine knotwood and black locust reduced the fungal decay of the tested sapwood blocks. Conclusions: The results of this research show that the less-valued knotwood of Scots pine and heartwood of black locust are a potential source of antifungal and antioxidant agents for bio-based wood preservatives.

Beech wood impregnation with hydrolyzed wattle tannin

“…A limited amount of tannin was also present in lumens and/or cell walls of other anatomical elements. Vek et al (2020) observed similar deposition in beech. Their impregnation involved hydrophilic heartwood extract of black locust that contained the same main unitrobinetinas the wattle bark extract (Venter et al 2012); this accumulated in a crystalline form on the lumina surfaces.…”

Coherent Investigation on a Smart Kinetic Wooden Façade Based on Material Passport Concepts and Environmental Profile Inquiry

“…The wood of European origin is called thuja. European thuja is fast-growing and weaker than North American wood [ 55 ]. Western Red cedar grows mixed with other coniferous species in the Western US and Canada [ 56 ].…”

Wood Extractives of Silver Fir and Their Antioxidant and Antifungal Properties

“…Samples were measured in triplicate. Identification of phenolic compounds was performed using external standards [18].…”

“…In general, polyphenols have three defensive functions: as biocides, radical scavengers, and metal chelators [15]. With their antifungal, antimicrobial, and antioxidant properties, phenolic extractives are treated as phytochemicals with potential applications, e.g., as bioactive agents in formulations for wood preservation, food protection, or even therapeutic purposes [3,[16][17][18][19]. Lignans have been reported as compounds with high antioxidative potency and radical scavenging capacity [20].…”