**2.3 Experimental**

Bioassays of EOs were performed by direct contact of fungi strains on agar medium according to the method reported by Remmal et al. [20]. Oils were first diluted in a sterile solution of tap water-agar at 0.2% in order to obtain a homogeneous mixture, then distributed in test tubes containing 13.5 ml of sterilized malt-agar medium (20 g/l malt extract and 15 g/l agar), and kept at 45°C in a water bath. To obtain the final oil concentrations in the culture medium ranging from 1/250 to 1/5000 v/v, aseptic volumes of 1.5 ml of different dilutions were then added to those tubes before pouring EO-medium mixtures into Petri dishes. Additional control dishes containing only 13.5 ml of culture medium and agar

**219**

**Table 1.**

*Durable Woods and Antifungal Activity of Their Essential Oils: Case of* Tetraclinis articulata*…*

solution at 0.2% (SA) alone were also prepared. Inoculation of Petri dishes was

treatment, three repetitions were prepared and incubated in the dark for 7 days at 22°C. At the end of each bioassay, minimal inhibitory concentration (MIC) [21]

According to the bioassay conducted on oils extracted from *T. articulata* and *C. atlantica* woods, a significant inhibitory effect on the four tested wood-decaying fungi was observed (**Table 1**) with different levels of inhibition. *T. articulata* root burl wood EOs showed, however, a strong inhibitory action against those fungi strains with oil dilutions over 1/4000 v/v. *G. trabeum* fungus was the most sensitive to the inhibitory effect of this essential oil since it was inhibited by concentrations between 1/5000 for *T. articulata* root burl oil and 1/1000 v/v for Atlas cedar oil. *O. placenta* was the most resistant strain since its growth inhibition was not reached until 1/400 concentrations for *C. atlantica* oil and 1/800 for *T. articulata* trunk

Previous studies by our team [5, 8] showed that *T. articulata* and *C. atlantica* woods were classified as very durable to durable (DC 1 and 2) and means of mass loss of test specimens was below 5.20% compared to those of Scot pine wood (control) (40.70%). According to their durability indexes (*X*) determined by NF EN 350-1 and CEN/TS 15083-1 standards [22, 23] and the biological risks defined by EN 335-2 standard [24], natural durability levels of those woods against wooddecaying fungi allow them to access high-risk classes of biological attacks 4 and 5 for an end-use without preservative treatment regarding decay fungi [25, 26]. Compared to similar studies on Moroccan coniferous woods (**Figure 1**), the natural durability of native Atlas cedar wood is similar to that of *C. atlantica* heartwood (DC 1 and 2) originated from a south Italian plantation [7], whereas *Pinus halepensis* and *P. pinaster* woods were considered as less durable (DC 4) [6, 27]. Generally, pine woods contain less active extractives than those of *Cupressaceae*. Adamopoulos et al. [28] reported that the weakness of natural durability of both heartwood and sapwood of *Pinus leucodermis* is related to low presence of bioactive extractives that

In addition, other works by our team [8, 29] revealed that EOs of *C. atlantica* wood is dominated by ketones (52.05%) and alcohols (26.58%), while those of thuya are dominated by alcohols (about 55–78%) and sesquiterpenes (13–22%) (**Table 2**). Major components of *C. atlantica* oil are, respectively, E-*γ*-atlantone, E-*α*-atlantone, 5-isocedranol, 9-iso-thujopsanone, cedranone, Z-*α*-atlantone,

Specific MIC *T. versicolor* 1/1000 1/4000 1/800

Global MIC 1/800 1/4000 1/400

*Minimal inhibitory concentrations (MIC) (v/v) determined for essential oils of thuya and Atlas cedar woods* 

**Thuya trunk wood**

*C. puteana* 1/1000 1/4000 1/400 *G. trabeum* 1/1200 1/5000 1/1000 *O. placenta* 1/800 1/5000 1/400

**Thuya root burl**

**Atlas cedar wood**

can inhibit the brown-rot fungus, *Coniophora puteana*.

cedroxyde, and 14-hydroxy-*δ*-cadinene [8] (**Table 3**).

**Essential oils fungal strains**

*by bioassay conducted on malt-agar medium on wood-decaying fungi.*

fragments of 10 days old fungal culture in malt-agar. For each

*DOI: http://dx.doi.org/10.5772/intechopen.87214*

was determined for each fungus.

**2.4 Results and discussion**

made by two 0.5 cm<sup>2</sup>

wood oil (**Table 1**).

#### *Durable Woods and Antifungal Activity of Their Essential Oils: Case of* Tetraclinis articulata*… DOI: http://dx.doi.org/10.5772/intechopen.87214*

solution at 0.2% (SA) alone were also prepared. Inoculation of Petri dishes was made by two 0.5 cm<sup>2</sup> fragments of 10 days old fungal culture in malt-agar. For each treatment, three repetitions were prepared and incubated in the dark for 7 days at 22°C. At the end of each bioassay, minimal inhibitory concentration (MIC) [21] was determined for each fungus.
