New Approach for Using of Mentha longifolia L. and Citrus reticulata L. Essential Oils as Wood-Biofungicides: GC-MS, SEM, and MNDO Quantum Chemical Studies.

Hayssam M Ali,Ashraf A Hatamleh,Mervat El-Hefny,Eslam M Abdel-Salam,Mohamed S Elshikh,Mohamed Z M Salem,Dunia A Al Farraj,Wael A A Abo Elgat,Ayman S Taha

doi:10.3390/ma14061361

Abstract

Background: Fungi growing on wood cause deterioration of stored food materials or discoloration of the wood itself, and the search for new and safe bioagents is recently needed. Methods: Essential oils (EOs) from aerial parts from Mentha longifolia L. and Citrus reticulata L., analyzed by gas chromatography-mass spectrometry (GC-MS), were tested for their antifungal activity by the vapor method against four common fungi, Aspergillus flavus, A. niger, A. fumigatus, and Fusarium culmorum, and confirmed by SEM examination as the oils applied on wood samples. Results: The most abundant compounds identified in the EO from M. longifolia were menthone and eucalyptol; in C. reticulata EO, they were β-caryophyllene, β-caryophyllene oxide, and β-elemene. EOs from M. longifolia and C. reticulata, at 500 and 250 µL/mL, showed potent antifungal activity against A. flavus and A. fumigatus, with 100% fungal mycelial inhibition growth (FMIG). C. reticulata and M. longifolia EOs, at 125 µL/mL, observed FMIG values of 98% and 95%, respectively, against A. fumigatus. M. longifolia EO, at 500 and 250 µL/mL, showed potent activity against A. niger, with 100% FMIG. F. culmorum completely inhibited (100% FMIG) EOs from M. longifolia and C. reticulata applied at 500 µL/mL. Pinus roxburghii Sarg. Wood, treated with M. longifolia at 125 µL/mL, showed inhibition zone values of 7.33 and 21.33 mm against A. flavus and A. niger, respectively. Conclusions: Both oils possessed good wood-biofungicide activity with the vapor method, as clearly shown by the SEM examination. These activities suggest their possible use as natural wood preservatives.

Highlights

Fungi such as Aspergillus niger, A. flavus, A. fumigatus, Alternaria tenuissima, Colletotrichum gloeosporioides, Fusarium culmorum, Penicillium chrysogenum, Rhizoctonia solani, and Trichoderma harzianum are capable of growing upon a wide range of organic substrates of wood, lignocellulosic materials, and food, which can lead to the deterioration of stored food materials or the discoloration of wood or paper substances [1,2,3,4,5,6,7,8,9,10,11]
Essential oils from M. longifolia and C. reticulata are of great interest with regard to their antifungal activities against Aspergillus flavus, A. niger, A. fumigatus, and Fusarium culmorum when applied as biopreservation for wood
Essential oil from M. longifolia, at 125 μL/mL, applied to Pinus roxburghii wood, showed an inhibition zone (7.33 mm) around the wood samples when inoculated with A. flavus; the inhibition zone was 15.33 mm when the wood samples were treated with the essential oil from C. reticulata against A. fumigatus and 21.33 mm when treated with the oil from M. longifolia against A. niger

Summary

Introduction

Fungi such as Aspergillus niger, A. flavus, A. fumigatus, Alternaria tenuissima, Colletotrichum gloeosporioides, Fusarium culmorum, Penicillium chrysogenum, Rhizoctonia solani, and Trichoderma harzianum are capable of growing upon a wide range of organic substrates of wood, lignocellulosic materials, and food, which can lead to the deterioration of stored food materials or the discoloration of wood or paper substances [1,2,3,4,5,6,7,8,9,10,11]. Methods: Essential oils (EOs) from aerial parts from Mentha longifolia L. and Citrus reticulata L., analyzed by gas chromatography-mass spectrometry (GC-MS), were tested for their antifungal activity by the vapor method against four common fungi, Aspergillus flavus, A. niger, A. fumigatus, and Fusarium culmorum, and confirmed by SEM examination as the oils applied on wood samples. EOs from M. longifolia and C. reticulata, at 500 and 250 μL/mL, showed potent antifungal activity against A. flavus and A. fumigatus, with 100% fungal mycelial inhibition growth (FMIG). Conclusions: Both oils possessed good wood-biofungicide activity with the vapor method, as clearly shown by the SEM examination. These activities suggest their possible use as natural wood preservatives

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