# Eco-Friendly Preservation of Pharaonic Wooden Artifacts using Natural Green Products
## 4 Discussion
Menthe oil showed an MIC against fourteen deterioration-causing fungal species in the 0.5-4 \(\mu\)L/mL range. Similar effects were recently found by [PERSON] et al. [74] with _Mentha piperita_ extracts against several fungi (_Penicillium brevicompactum_, _P. critrium_, _P. crustosum_, _P. expansum_, _P. funciulosum_, _P. glabrum_, _P. chrysogenum_, _P. oxalicum_, _P. polonicum_, and _Talaromyces purporugenus_). Tea tree oil (_M. alternifolia_) caused the complete inhibition of _A. terreus_ at 0.75 \(\mu\)L/mL. [PERSON] et al. [75], in accordance with our results, indicated that tea tree oil had a lower efficacy against decay fungi than thyme oil, which contains phenolic antifungal compounds. _Eucalyptus_ oil (_E. globulus_; MIC: 1-8 \(\mu\)L/mL) was found with a low efficiency if compared with the previous one. Similar results were found by other authors [76; 77; 78; 79; 80], who found that it was effective against _Ullodadium_ spp., while _Penicillium_ spp. was resistant to the oil. Rosemary oil (_R. officinalis_, MIC: 1-8 \(\mu\)L/mL) and lavender oil (_L. tatifolia_, MIC: 2-8 \(\mu\)L/mL) had the lowest antifungal effects. [PERSON] et al. [74] studied the effect of _Lavandula angustifolia_ volatile essential oils against _Penicillium_ sp., giving an inhibition zone 15.50 \(\pm\) 1.38 mm at a 0.75 \(\mu\)L/mL concentration. On the other hand, no activity was observed against _Rosemarius officinalis_ at 0.125 \(\mu\)L/mL. In the current study, the isolated _Aspergillus_ spp. were the most resistant species against all the ten tested EOs. This fact can be due to the melanin pigment found in the thick cell walls of _Aspergillus_ that plays a protective role by allowing them to survive in unfavorable environmental conditions [81]. Additionally, many enzymes produced by _Aspergillus niger_ can also detoxify components of EOs into inactive forms, as previously reported [82; 83]. In the present study, thyme oil completely inhibited the amylase activity of _A. fumigatus_ and _A. terreus_ at 0.5 \(\mu\)L/mL, while the amyloid activities of the _A. flavus_ and _A. niger_ were fully suppressed at 0.75 \(\mu\)L/mL. [PERSON] and [PERSON] [84] stated that the delay of enzyme production by essential oils may be caused by the efficient components of thyme. Essential oils may have some components that cause the amylase inhibitory effect, according to [PERSON] et al. [85], who found some EOs with strong activity against a-amylase and tyrosinase. The three tested essential oils (thyme, geranium, and cinnamon), still at the lowest concentrations, can reduce the enzymatic activities tested in this study (amylase, cellulase, and protease) for the four selected fungal isolates (_Aspergillus flavus_, _A. fumigatus_, _A. niger_, and _A. terreus_). The obtained results are in accordance with [PERSON] and [PERSON] [44], who showed that EOs affected the enzyme production of two pathogenic fungi (_Fusarium solani_ and _Trichoderma virens_) with weak enzyme production during the first growth stage, and subsequently the level of enzyme production decreased along with the inhibition of fungal growth. [PERSON] et al. [86] used thyme oil at a concentration of 0.01 \(\mu\)L/mL against _Neocallimastix_ spp. to reduce the activity of some enzymes. The results here reported are in agreement with [PERSON] et al. [87], who revealed that the activities of extracellular hydrolytic enzymes (amylase, protease, pectinase, and endocellulase) were stimulated by low concentrations of EOs. The antifungal activities of the tested essential oils in the current study agree with [PERSON] et al., [PERSON] et al., and [PERSON] et al. [88; 89; 90]. The experimental aged wooden cubes treated with the most efficient thyme essential oil were analyzed using a scanning electron microscope, energy dispersive X-ray analysis (SEM & EDX), and Fourier-transform infrared spectroscopy (FTIR). The observed drop in the crystallinity index in the untreated wood may be due to fungal deterioration, as recorded by [PERSON] et al.