Efficacy Of Plant Extracts Against Fungi of Wood

Abstract

Wood is naturally susceptible to biodeterioration owing to its organic nature. This has consistently put pressure on forest resources. Increasing population and other infrastructural developments have also exerted pressure on tropical forests. Synthetic chemicals have been developed to mitigate the effects of wood biodeterioration, elongate the lifespan of wood, and reduce pressure on the forest. However, synthetic chemicals used in wood preservation have negative effects on the environment. Environmentally friendly organic materials have been used to mitigate the effects of chemicals on both humans and the environment. Plant extracts are readily available and environmentally friendly, thereby reducing the cost and eliminating the toxicity and environmental effects of conventional wood preservatives. Various parts of different wood species are useful for suppressing and eliminating fungal growth. Therefore, it is imperative to review the attributes of tropical wood species that have proven efficacy as wood preservatives.

Full text

Proceedings:
Society of Wood Science and
Technology June
2023
Compiled by
Victoria Herian

Efficacy Of Plant Extracts Against Fungi of Wood
K. M. Ogunjobi1* – Adekunle Adetogun2 – Victor Jayeola3 – Olorunfemi Olusola4
1Senior Lecturer, Department of Forestry and Wildlife Management
Federal University of Agriculture, Abeokuta, Ogun State,
Nigeria *Corresponding author
ogunjobikm@funaab.edu.ng
2Professor, Department of Forestry and Wildlife Management
Federal University of Agriculture, Abeokuta, Ogun State, Nigeria
adetogunac@funaab.edu.ng
3Researcher, Department of Forestry and Wood Sciences
Stellenbosch University, South Africa
thevictorjay@gmail.com
4Assistant Lecturer, Department of Forestry and Wildlife Management
Federal University of Agriculture, Abeokuta, Ogun State, Nigeria
olorunfemio@funaab.edu.ng
Abstract. Wood is naturally susceptible to biodeterioration owing to its organic nature. This
has consistently put pressure on forest resources. Increasing population and other
infrastructural developments have also exerted pressure on tropical forests. Synthetic
chemicals have been developed to mitigate the effects of wood biodeterioration, elongate the
lifespan of wood, and reduce pressure on the forest. However, synthetic chemicals used in
wood preservation have negative effects on the environment. Environmentally friendly
organic materials have been used to mitigate the effects of chemicals on both humans and
the environment. Plant extracts are readily available and environmentally friendly, thereby
reducing the cost and eliminating the toxicity and environmental effects of conventional
wood preservatives. Various parts of different wood species are useful for suppressing and
eliminating fungal growth. Therefore, it is imperative to review the attributes of tropical
wood species that have proven efficacy as wood preservatives.
Keywords: Efficacy, biodeterioration, plant extract, synthetic, wood preservation,
environment friendly
INTRODUCTION
Owing to its unique characteristics, wood has remained one of the most significant renewable
natural resources available to humans throughout history (Hingston et al. 2001, Wang et al
2005). However, non-durable wood is treated with preservatives to prevent decay caused by

wood-boring crustaceans and mollusks, fungi, and insects (Craig et al. 2001, Yalinkilic
2000). When wood is used as a building material, it is typically treated with a chemical
preservative to prevent damage caused by aggressive biodeteriogens (Craig et al. 2001).
Therefore, the development of methods for extending the service life of wood has always
been of interest to researchers in the timber industry (Wang et al. 2005).
Effective synthetic wood preservatives, such as copper-based agents (i.e., chromated copper
arsenate), triazoles (azaconazole, propiconazole, tebuconazole), pentachlorophenol, and
boron-based fungicides (Edlund et al 1999; Freeman and McIntyre 2008; Lesar et al 2012),
have been utilized for this purpose. However, because of environmental and health concerns,
the use of many of these chemicals has been restricted, necessitating the development of
alternative wood protection agents and methods based on nontoxic natural products (Lesar
et al 2012, Edlich et al 2005; Singh and Singh 2012).
Today, eco-friendly wood protection is the subject of extensive research, encompassing a
variety of approaches. Since the growth of wood-degrading fungi is dependent on the
availability of water, one method is moisture control using natural hydrophobic agents, such
as lubricants and resins of plant origin or plant oils (Gonzalez-Laredo et al. 2015, Humar and
Lesar 2013, Patachia and Croitoru 2016, Terziey and Panov 2011). Utilizing plant extracts
with biocidal properties and incorporating them into the wood structure (Singh and Singh
2012, Gonzalez-Laredo et al 2015, Teaca et al. 2019) is a second method for extending the
service life of the wood. The purpose of this article is to provide an overview of current
research on various plant extracts with proven biocidal activity that may be beneficial for
protecting wood against fungi.
A REVIEW OF PLANT EXTRACTS USED IN WOOD PROTECTION
In some regions of the world, plant derivatives have been used for generations to improve
the appearance and durability of wooden products, such as furniture and strolling poles. With
the introduction of synthetic and inorganic compounds, which have proven to be more
effective against wood-degrading organisms, the use of plant-derived products for wood
protection has become less appealing. However, there is an urgent need to supplant synthetic
and inorganic compounds with organic biocides because of their toxicity to human health
and negative environmental impact. The chemical compounds Alkaloids, flavones,
flavonoids, phenolics, terpenes, tannins, and quinones are abundant in plants. Secondary
metabolites account for up to 30 percent of a plant's dried mass and play a crucial role in
defense against microbial pathogens, herbivores, and various forms of abiotic stress.
Numerous plants have been used by humans as remedies and food additives since the
discovery of phytochemicals and their unique properties. Recognizing the chemical structure
and functions of specific plant components permits the development of efficient methods for
their extraction from plant tissues and their commercial application in pharmaceuticals,
cosmetics, functional foods, and coloring agents. As biopesticides, insecticides, and
fungicides to protect crop plants and biodegradable materials (Mazid et al. 2011, Adamczyk
et al. 2017, Vasconsuelo and Boland 2007, Bhagat et al. 2014), there is also considerable
interest. Diverse plant extracts with antifungal properties are of interest as potential sources

of natural substances that can be used as alternative wood preservatives against degradation.
The high availability of plant material in general and the possibility of using industrial waste
from the processing of various crops can increase the economic viability of the entire process
of obtaining them, thereby allowing for the potential widespread application of plant
preservatives in the wood industry.
Efficacy of Essential Oils
Essential oils are natural mixtures of volatile secondary metabolites of various plants that can
be extracted from plant materials via distillation, mechanical expression, or solvent
extraction. They contain a variety of chemical compounds that are responsible for the
distinctive aroma of the plants from which they are extracted. The primary components are
terpenes, which include alcohols, aldehydes, hydrocarbons, ethers, and ketones, with
demonstrated biological activity, including antioxidant, antibacterial, and antifungal
properties. Essential oil-containing plants have been used for centuries in folk medicine and
as flavoring and preservative agents in food (Masango 2005, Edris 2007, Kalemba and
Kunicka 2003). Their composition and potential therapeutic activities, such as
antiinflammatory, antimicrobial, antiviral, anticancer, antidiabetic, and antioxidant, have
been extensively investigated (Edris 2007, Kalemba and Kunicka 2003, Swamy et al. 2016).
They are potentially useful as preservatives for a wide variety of products (Herman et al.
2013, Prakash et al. 2015, Pandey et al. 2017) due to the growing interest in biodegradable,
nontoxic natural substances with antimicrobial properties. Also, some attempts have been
made to use essential oils from common plants, herbs, and seasonings as wood-protecting
agents due to their demonstrated antifungal properties against mold and wood-decaying fungi
(Voda et al. 2003, Hussain et al. 2013, Bahmani and Schmidt 2018; Kartal et al 2006; Pánek
et al. 2014, Xie et al. 2017, Zhang et al. 2016)
Various essential oils have been tested in vitro against various fungal species to determine
their effectiveness. Using the agar dilution technique, Voda et al. (2003) found that anise,
basil, cumin, oregano, and thyme oils were highly effective against brown-rot fungus
Coniophora puteana and white-rot fungus Trametes versicolor. They determined that thymol,
carvacrol, trans-anethole, methyl chavicol, and cumin aldehyde were the most effective
compounds in inhibiting the proliferation of both fungi. Additional research has revealed a
correlation between the molecular structure of oxygenated aromatic essential oil compounds
and their antifungal activity against wood-rotting fungi (Voda et al 2004). Chittenden and
Singh (2011) demonstrated in vitro that 0.5% concentrations of cinnamon and geranium oils
are antifungal against the brown-rot fungi Oligoporus placenta, C. puteana, Antrodia xantha,
sap stain fungi Ophiostoma floccosum Mathiesen, Ophiostoma piceae, Sphaeropsis sapinea,
and Leptographium procerum, and a mold fungus, Trichoderma harzianum (Molecules 2020,
25, 3538, 4 of 24). In addition, they discovered the antifungal properties of aniseed, oregano,
and lema (a compound of 50% New Zealand manuka and 50% Australian tea tree) oils
against some of the fungi previously mentioned. Zhang et al (2016) reported the antifungal
efficacy of purified monoterpenes, including -citronellol, carvacrol, citral, eugenol, geraniol,
and thymol, against wood white-rot fungi Trametes hirsuta, Schizophyllum commune, and
Pycnoporus sanguinolentus. Xie et al (2017) confirmed the antifungal properties of the

essential oils of Origanum vulgare, Cymbopogon citratus, Thymus vulgaris, Pelargonium
graveolens, Cinnamomum zeylanicum, and Eugenia caryophyllata against the wood-
decaying fungus T. The most active compounds in hirsuta and Laetiporus sulphurous were
carvacrol, citron, citronellol, cinnamaldehyde, eugenol, and thymol. Cinnamaldehyde, -
methyl cinnamaldehyde, (E)-2-methyl cinnamic acid, eugenol, and isoeugenol inhibited the
growth of the white-rot fungus Lenzites betulina and the brown-rot fungus L. sulphurous
(Cheng et al 2008). Reinprecht et al (2019) found that among five distinct essential oils (basil,
cinnamon, clove, oregano, and thyme), the oil with the maximum antifungal activity against
the brownrot fungus Serpula lacrymans and the white-rot fungus T. The highest versicolor
content was observed for basil oil (predominantly linalool) and the lowest for clove oil
(predominantly eugenol). These results were confirmed using wood samples treated with
specific essential oils. Pánek et al. (2014) investigated the antifungal efficacy and stability of
beech wood treated with 10% solutions of ten different essential oils (birch, clove, lavender,
oregano, sweet flag, savory, sage, tea tree, thyme, and a mixture of eucalypt, lavender, lemon,
sage, and thyme oils) against brown-rot fungus C. T. puteana and T. versicolor. versicolor.
After a complex expedited aging procedure, they discovered that the most effective against
C. clove, oregano, sweet flag, and thyme oils contained phenol compounds such as carvacrol,
eugenol, thymol, and cis-isoasarol trimethyl ether. The mass losses of birch wood were 0.9,
0.666, 0.57, and 0.85 %, respectively. Clove, sweet flag, and thyme oils were the most
effective against mold (Aspergillus niger and Penicillium brevicompactum) in the filter paper
tests. These lubricants are potentially beneficial for the protection of interior wood.
Unsurprisingly, none of the lubricants examined were efficacious against T. versicolor, which
may be due to the unique enzyme apparatus of white-rot fungi capable of degrading lignin
and other phenolic compounds. The efficacy of thyme oil against C. pumpkin and Jones et
al. (2011) confirmed the presence of niger. In addition, they demonstrated that basil, yarrow,
and calendula oils have antifungal activity against C. respectively from P. placenta and P.
placenta; however, the two latter oils were only efficacious when used pure. Chittenden and
Singh (2011) reported that wood treated with 3% eugenol exhibited high resistance to C, with
a mass loss of 1%. puteana, O. placenta, and vitamin A xantha. However, they discovered
that eugenol could be readily leached from wood, suggesting that it is unsuitable for the
protection of outdoor wood. Kartal et al (2006) treated sugi wood with a formulation
containing cassia oil, achieving high wood resistance to brown-rot Tyromyces palustris
(0.7% mass loss) and white-rot C. versicolor fungi (3.6% mass loss). Yang and Clausen
investigated the antimicrobial properties of seven essential oils, including ajowan, dill weed,
Egyptian geranium, lemongrass, rosemary, tea tree, and thyme oil. They discovered that
vapors from dill weed oil and immersion treatment of Southern yellow pine samples with
thyme or geranium effectively inhibited the development of A. thaliana for at least 20 weeks
(Yang and Clausen 2007). Bahmani et al (2018) determined that applying lavender,
lemongrass, and thyme oils to Fagus orientalis and Pinus tadea wood could provide effective
protection against A. niger, Penicillium commune, C. puteana, T. versicolor in addition to
Chaetomium globosum. Salem et al. (2016) demonstrated the antifungal activity of Pinus
rigida and Eucalyptus camaldulensis oils applied to the surfaces of Fagus sylvatica, P. rigida,
and P. sylvestris wood, and Hussain et al. (2013) reported similar antifungal properties of
clove oil applied to indigenous Indian wood.

It has been demonstrated that a wide array of essential oils derived from indigenous plants
from all over the globe possess antifungal and antifungal properties. The essential oil from
the leaves of the Taiwanese cinnamon tree Cinnamomum osmophloeum Kaneh, containing
cinnamaldehyde as the most abundant antifungal component, has been reported to be
effective against several white- and brown-rot fungi, such as Coriolus versicolor and
Laetiporus sulphureus (Wang et al. 2005). Kartal et al. (2006) also confirmed the antifungal
properties of cinnamaldehyde when applied to sugi wood, efficiently enhancing the wood's
resistance to brown-rot T. palustris (0.6% mass reduction) and white-rot C. versicolor fungi
(3.8% mass loss). Chittenden and Singh (2011) also obtained favorable results for Radiata
pine wood treated with a 3% cinnamaldehyde solution, where the mass loss against C was
1%. pumpkin and A. xantha, and approximately 3% versus O. placenta.
The leaf and fruit oils of another Taiwanese tree, Juniperus formosana Hayata, were tested in
vitro by Su et al. (2013) for their antifungal properties against seven mold fungi (Aspergillus
clavatus, A. niger, Ch. globosum, Cladosporium cladosporioides, Myrothecium verrucaria,
Penicillium citrinum, and T. viride), two white-rot fungi (T. versicolor and Phanerochaete
chrysosporium), and two brown-rot fungi (Phaeolus schweinitzii and Lenzites sulphureum).
Cadinol and elemol were the most active compounds in the antifungal properties of leaf oil.
Owing to the presence of citronellal and citronellol, the leaf oil of Taiwanese Eucalyptus
citriodora exhibited high antifungal activity against mold and wood-decaying fungi (Su et al.
2006).
Cheng et al. (2004) reported that the essential oil extracted from Calocedrus formosana Florin
leaves has high antifungal activity. C. Formosana is a Taiwanese endemic tree species that is
distinguished by its natural resistance to decomposition. The most potent antifungal effect
against L. betulina, Pycnoporus coccineus, T. versicolor, whereas L. Two oil compounds
exhibited sulphurous properties: -cadinol and T-muurolol. Mohareb et al. (2013) investigated
the antifungal activity of the essential oils of eighteen distinct Egyptian plants against the
wood-rotting fungi Hexagonia apiaria and Ganoderma lucidum. The sapwood of Scots pine
treated with Artemisia monosperma, Citrus limon, Cupressus sempervirens, Pelargonium
graveolens, Schinus molle, and Thuja occidentalis oils exhibited the greatest resistance. In
turn, the efficacy of neem oil, which contains the antifungal agent azadirachtin, against S.
commune, Fusarium oxysporum, Fusarium proliferatum, and C. Rawat et al. (2018) reported
that P. puteana and Alternaria are substitute fungi. Hussain et al. (2013) obtained comparable
results by demonstrating that local Indian wood treated with neem oil is resistant to various
molds. Several novel strategies for enhancing the antifungal activity of essential oils as wood
preservatives are worth mentioning. Among them is the use of essential oil complexes with
methyl--cyclodextrin. Cai et al. (2020) exposed Southern pine wood to brown-rot fungi
Gloeophyllum trabeum and P. placenta after treating it with compounds of eugenol,
transcinnamaldehyde, thymol, and carvacrol with methyl--cyclodextrin. Even after leaching,
the degradation resistance of wood treated with specific complexes was greater than that of
the control samples or wood specimens impregnated with essential oils individually. The use
of complexes containing natural compounds such as essential oils appears to have
tremendous potential for extending the durability of wood products.

Efficacy of Waxes and Tannins
In addition to oils, resins, tannins, and other plant extracts, the bark of numerous tree species
is an abundant source of antioxidant and antimicrobial agents. Tannins have long been used
as adhesives and wood preservatives (Lotz and Sleeter 1980, Laks 1988, Lotz and Hollaway
1988, Lotz 1993). Tannins and tannin-derived compounds are difficult to fix in the wood
after treatment, but satisfactory wood protection has been achieved using additives, such as
ferric chloride and metallic salts (Lotz and Sleeter 1980, Laks et al. 1988, Laks 1991, Lotz
and Hollaway 1988, Lotz 1993). Other products derived from the bark, such as bio-oils
derived via pyrolysis, have also been evaluated as wood preservatives (Suzuki et al. 1997).
Considering bark as a source of organic biocides, it is important to keep in mind that the
bioactivity of bark extracts from diverse sources will vary, as demonstrated by studies
evaluating the antifungal properties of barks from various tree species (Yang et al 2004; Yang
2009). Bark components such as lubricants, resins, and phenolic extractives have also been
used as adhesives. Brandt (1953) described mangrove tannin–formaldehyde resin as a
highstrength water-resistant adhesive. Wattle tannins are recognized as water-resistant
adhesives (Plomely 1966). Wax and resin extracted from the epidermis of various pine
species, such as Radiata pine and ponderosa pine, have been utilized as bonding agents in
the production of wood products (Anderson et al. 1961, Hall et al. 1960). Passialis and
Voulgaridis (1999) studied the characteristics of natural waxes extracted from Aleppo pine
needles and bark. Wood specimens treated with these waxes exhibited hydrophobic
properties, with bark extracts exhibiting greater hydrophobicity than needle extracts. The
antimicrobial activity of guayule resin was investigated by Bultman et al in 1991. Resin from
the wood and stem of guayules (Parthenium argentatum Gray) protects wood-destroying
organisms, such as decay fungi, termites, and marine borers, when impregnated with wood
(Nakayama et al. 2001). The disintegration resistance of particleboards impregnated with
Pinus bruita bark extracts is enhanced (Nemli et al. 2006). Other characteristics of the board,
such as thickness swell, were also improved. Recent research (Si et al. 2011) has
demonstrated that phenolic glucosides extracted from the bark of Populus ussuriensis possess
antioxidant properties. The potential use of these compounds and antioxidants in the bark of
other tree species (Zhang et al. 2006) for wood protection should be investigated.
Efficacy of Wood Extractives
The chemical composition of wood also includes minor amounts of extraneous materials,
mostly in the form of compounds known as extractives (usually 4–10%, even up to 30%
depending on the wood species, growth conditions, and time of year when the tree is cut) and
minerals (ash), primarily calcium, potassium, and magnesium, in addition to manganese and
silica (Miller 1999, Nascimento et al. 2013). Bark, foliage, and roots have higher
concentrations of extractives than stem wood because of the presence of both inorganic and
organic components. These extractives contribute to wood characteristics, including color,
odor, flavor, degradation resistance, density, hygroscopicity, and flammability (Fengel and
Wegener 2003, Rowell et al. 2013). These wood components can be extracted from wood
using solvents such as water, alcohol, acetone, benzene, toluene, ether, or solvent mixtures
[e.g., alcohol/benzene or toluene].

Characterization of biologically active components from termite-resistant timbers could
result in increased protection of wood against termites through treatment with extracts or
synthetic compounds with structures similar to those of the biologically active components
(Carter et al. 1978). Hardwood and softwood may contain comparable quantities of
extractives, but their chemical compositions are distinct (Fengel and Wegener 2003).
Tannins, other polyphenolic compounds, colored substances, essential oils, lipids, resins,
lubricants, gum starch, and basic metabolic intermediates are present in varying proportions.
These compounds include quinones (Carter et al. 1978, Ganapaty et al. 2004), flavonoids
(ReyesChilpa et al. 1998, Ohmura et al. 2000, Chen et al. 2004, Morimoto et al. 2006),
terpenoids (Chang et al. 2000, Watanabe et al. 2005), and alkaloids. Wood's natural durability
is typically proportional to its extractives content and composition (Carter et al 1978; Taylor
et al. 2006, Santana et al. 2010, Andrady et al. 2015, Carter et al. 1978, Taylor et al. 2006).
When natural extractives compounds from wood and plants are compared to common
substances used for wood preservation in terms of their efficacy, the natural ones are
generally preferred for safety and versatility due to their biocide and antioxidant properties,
as well as their metal-binding ability (Kartal et al. 2006, Syofuna et al. 2012, GonzálezLaredo
et al. 2015, Sablik et al. 2016). These extractives reduce the hygroscopicity of wood surfaces,
thereby inhibiting the decomposition of a wide variety of biological organisms, including
human pathogens, insects, and fungi, with a positive effect on wood durability. Schultz et al.
(1995) and Schultz et al. (2002) report that heartwood extracts may exhibit significant
antifungal and antioxidant properties. Specific applications of wood and plant extracts
include long-term preservation (for condensed tannins), antifungal and subterranean termite
protection (for flavonoids), repellency and toxicity against termites (for quinones), and
heartwood resistance to fungal decay (for stilbenes). The extraction method and solvents may
affect the initial antifungal activity of various extractive groups.
There are native extractive compounds, such as those obtained from the heartwood of durable
species, such as black locust (Robinia pseudoacacia L.) and African padauk (Pterocarpus
soyauxii Taub.), which exhibit enhanced antifungal activity under laboratory testing
conditions by enhancing the resistance to decay of impregnated European beech (Fagus
sylvatica L.) wood samples (Sablik et al. 2016).
The presence of condensed tannins (proanthocyanidins or polyflavonoid tannins) in the bark
extract of mimosa (Acacia mollissima) and quebracho heartwood extract (Schinopsis
lorentzii) is effective for conferring increased fungal resistance in testing against both white
and rot fungi (Tascioglu et al. 2013, González-Laredo et al. 2015, Tascioglu et al. 2012)
demonstrating that these extractive compounds are effective as wood anti-decay agents in
indoor applications, even at low concentrations.
Extracts from the heartwood of certain Amazonian woody species (Rodrigues et al. 2012)
demonstrate antifungal activity against soft rot, brown rot, and white-rot fungi, comparable
to that of commercially available preservative coatings. The leaf extract of the camphor tree
(Cinnamomum camphora) is abundant in biocides (terpene alcohols: terpineol, linalool, and
4-terpineol; a monoterpenoid: eucalyptol, also known as cineole; a terpene ketone: camphor).

However, their antifungal activity is limited owing to their volatility and thermal instability.
In such situations, fixation agents (i.e., melamine-modified urea formaldehyde resin
prepolymers) are required. As bamboo preservatives, these compounds exhibit good
resistance to decay and insects and favorably affect the resulting mechanical properties (Xu
et al. 2013).
A combination of certain metals (acting as chelators for some fungal enzymes) and biocide
extractives (condensed tannins or proanthocyanidins; gallic acid derivatives derived from
tannic acids) is most effective for enhancing antifungal activity when these compounds
exhibit a synergistic effect (González-Laredo et al. 2016). Antioxidants acting as scavengers
for the free radicals involved in wood decay caused by fungi (Morris and Stirling 2012) are
an additional effective method for enhancing the antifungal activity of wood extractives.
An extractive compound found in the seeds, leaves, and bark of the neem tree (Azadirachta
indica) functions as a biocide against fungi, either alone or in combination with copper
sulphate and boric acid (Islam et al. 2009). It is an effective insect repellent (effective against
termites, wood-boring insects, and other insects).
Environmental and biological factors influence the efficacy of wood extracts as fungicides,
as their antifungal activity depends on their ability to inhibit the development of fungal cells
on wood substrates by inhibiting enzymatic processes and other phenomena.
Multiplecomponent biocide systems (such as natural extractives and synthetic antifungal
agents) have been shown to protect the wood from decay fungi, mold fungi, and termites for
interior applications (Clausen and Yang 2007). Overall, the use of wood extracts as UV
stabilizers on a large industrial scale is restricted due to their high-water solubility and ease
of leaching from wood.
CONCLUSION
As can be seen, plant extracts have a great deal of potential for wood protection, as they
exhibit a wide range of antimicrobial activities. They are renewable, easily accessible or
inexpensively obtainable, non-toxic or significantly less eco-toxic than conventional
chemical biocides, and environmentally benign. Nonetheless, they have several drawbacks,
such as high heterogeneity depending on the source from which they are derived (i.e.,
essential oils, wood extractives), insufficient retention within the impregnated wood tissue,
easy leachability, selective or uneven activity against specific types of fungi, and high
susceptibility to biodegradation. The introduction of natural biocides from plant extracts to
the market is hampered by discrepancies between laboratory tests and reported field
performance, as well as by legislative issues stemming from the need to comply with various
directives (relating to construction materials and application of biocides) and the absence of
standards defining the quality, composition, performance, and application of specific
naturalbased protective formulations. Therefore, additional research in the discipline is
required. Responding to all of the challenges that face the development of natural
preservatives aimed specifically at the protection of wood and wood-based products may be
too expensive to be profitable. Therefore, collaborating with other industries interested in the
exploitation of specific natural active compounds such as pest control, food, and

pharmaceutical applications, may be a viable alternative. The development of new generation
natural preservatives with minimal impact at the end of the treated wood's stage life is a
necessity from the standpoints of human health and environmental protection in this day and
age when extending the lifespan of wood products is of great interest and importance.
Although this review does not exhaust the subject, as there are hundreds of scientific studies
on the antifungal activity of natural compounds, it provides a comprehensive overview of
the current state of research in the field and the prospects for the development of sustainable
alternative wood protection based on natural compounds.
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