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Biodegradation of wood by fungi is recognized as one of the most serious problems for wooden structures and forest management. This study evaluated the fungicidal activity of 6 plant essential oils ( Origanum vulgare , Cymbopogon citratus , Thymus vulgaris , Pelargonium graveolens , Cinnamomum zeylanicum and Eugenia caryophyllata ) against the wood-rot fungi, Trametes hirsuta and Laetiporus sulphureus . Results from antifungal tests revealed that six essential oils showed good antifungal activities, in which, O. vulgare was the most toxic to the wood-rot fungi, with the IC 50 values against T. hirsuta and L. sulphureus of 79.1 and 36.9 μg/mL, respectively. The composition of six essential oils was indentified by using gas chromatographic-mass spectrometry. The six major compounds from 6 essential oils were tested individually for their fungicidal activities against two wood-rot fungi. Results from the antifungal tests demonstrated that the six major compounds exhibited strong fungicidal activity. In addition, carvacrol was the most toxic against the wood-rot fungi, with the IC 50 values against T. hirsuta and L. sulphureus of 33.6 and 17.2 μg/mL, respectively. Furthermore, phenol and aldehyde groups were more toxic than alcohol. The results show that the six plant essential oils and their major chemical constituents have potential for the development of natural wood preservatives. [ABSTRACT FROM AUTHOR]

Rhizoctonia solani and Fusarium oxysporum are very well known phytopathogens with worldwide spread that cause one of the most destructive diseases, resulting significant yield losses in crop production. In order to find effective fungicides for controlling phytopathogen, the structure-activity relationships of cinnamaldehyde and eugenol derivatives against R. solani and F. oxysporum were evaluated. Additionally, the composition and fungicidal activity of Cinnamomum cassia and Syzygium aromatica essential oils was assessed. Cinnamaldehyde (49.75%) is the major compound in cinnamon bark oil, and eugenol (89.17%) is most abundant in clove bud oil. The clove bud oil exhibited good antifungal activities against R. solani and F. oxysporum (IC 50 = 106.5 and 149.9 μg/mL, respectively). Cinnamon bark oil showed a lower activity than clove bud oil. The fungicidal activity of cinnamaldehyde (IC 50 = 75.4 and 156.9 μg/mL, respectively) and eugenol (IC 50 = 58.9 and 52.9 μg/mL, respectively) against R. solani and F. oxysporum was also evalutated. Comparisons of the antifungal activities of cinnamaldehyde and eugenol derivatives revealed that α-methylcinnamaldehyde, α-methylcinnamic acid, methyleugenol, acetyleugenol, isoeugenol, methylisoeugenol, and acetylisoeugenol showed good antifungal activities against R. solani and F. oxysporum . In structure-activity relationships, the fungicidal activity of cinnamaldehyde derivatives could be related to conjugated double bond and the length of CH chain outside the ring. In addition, the presence of the lipophilicity may have a considerable influence on the toxicity of phenylpropenes. The present approach may help future work in the search for fungicidal compounds. [ABSTRACT FROM AUTHOR]

Biodegradation of wood by fungi and termites is recognized as one of the most serious problems for wooden structures. In this study, we analyzed the antitermitic and antifungal activities of flower buds essential oil from Syzygium aromaticum and its dominant constituents. Essential oil components were analyzed by gas chromatography and the major compound of essential oil was eugenol (90.6%). The results demonstrated that at the dosage of 50 μg/g, clove essential oil had 100% mortality to Reticulitermes chinensis after testing for 5 d. Furthermore, we found eugenol killed all termites after testing for 3 d, with an LC 50 value of 12.1 μg/g. Meanwhile, we also found clove essential oil and eugenol displayed activity against three fungi, Trametes hirsuta , Schizphylhls commne , and Pycnoporus sanguineus . We found eugenol was principal antifungal constituent of clove oil. The IC 50 values of eugenol against T. hirsuta , S. commne , and P. sanguineus were 83.6, 116.1, and 102.4 μg/mL, respectively. In addition, comparisons of the termite mortality and antifungal indices of eugenol and its congeners proved that eugenol exhibited the strongest antitermitic and antifungal activities. The clove oil and eugenol have potential for the development of natural wood preservatives. [ABSTRACT FROM AUTHOR]

Highlights: [•] Forty-two monoterpenes were evaluated for termiticidal activity toward Reticulitermes chinensis. [•] The (+)-pulegone and carvacrol were the most toxic monoterpenes to R. chinensis. [•] The termiticidal activity of oxygenated hydrocarbon was higher than the hydrocarbon. [ABSTRACT FROM AUTHOR]

Abstract: Essential oils were extracted by hydrodistillation from the leaves of Cryptomeria fortunei from the principal habitats in China. The essential oil yields of samples from various locations ranged from 0.61 to 1.66% (w/w). GC–MS analysis revealed eighty-seven compounds, constituting 85.89–94.75% of the total essential oils. The main constituents were kaurene (0–44.69%), phyllocladene (0.07–32.98%), kaur-16-ene (0–32.28%), elemol (5.28–18.92%), α-cadinol (0–11.39%), α-eudesmol (0–11.21%), α-pinene (2.32–9.15%). The samples were separated into 3 chemotypes by hierarchical cluster analysis, according to the composition of the corresponding essential oils. Chemical composition of essential oils was significantly related to nine geographic distributions among populations. Our results revealed chemical polymorphism in the essential oils of the C. fortunei leaf in China. The chemical variability could be attributed to genetic and environmental factors. The chemical diversity of the oils offers opportunity to choose C. fortunei leaves and essential oils with preferential compound for green plant protection, pharmaceutical, perfume and food industries. [Copyright &y& Elsevier]

Abstract: The essential oils obtained by hydrodistillation from leaves of Chinese native Cryptomeria japonica and Cryptomeria fortunei were analyzed by GC and GC–MS. Fifty-seven compounds were identified in the essential oils of C. japonica with α-elemol (20.12%), kaur-16-ene (14.84%), β-phellandrene (5.97%), β-elemene (5.87%), α-eudesmol (5.62%) and β-eudesmol (5.03%) as main constituents. Forty components were identified in the oil of C. fortunei with kaurene (34.04%), α-elemol (13.34%), γ-eudesmol (10.80%), β-eudesmol (10.16%), α-pinene (2.75%) and γ-cadinene (1.92%) as the most abundant components. This study demonstrated the occurrence of α-elemol chemotype in C. japonica and kaurene chemotype in C. fortunei from China. The essential oil compositions of two Cryptomeria samples were shown that they can be used for green plant protection, pharmaceutical, perfume and food industries. [Copyright &y& Elsevier]

• Illicium verum powder and its volatiles had fumigation activity to Cryptolestes ferrugineus. • Only the volatile component trans -anethole showed effective biological activity. • Estragole could did significantly enhance fumigant efficiency of trans -anethole. • Trans -Anethole affects the beetles acetylcholinesterase activity of nervous system. The safe storage and protection of grain includes the exploitation of plant-based fumigants as a green control technology. This study first determined the fumigant toxicity of 12 traditional Chinese medicinal plants against adults of the rusty grain beetle, Cryptolestes ferrugineus (Stephens), one of the most ubiquitous and pestilent grain storage pests worldwide. Exposure to volatiles released from Illicium verum Hook. f. powder was found to be by far the most lethal. Illicium verum power and its volatiles eluent were then confirmed to be highly effective in killing both larvae and adults of C. ferrugineus. Star anise volatiles also showed good biological activity against Lasioderma serricorne (Fabricius) and Sitophilus zeamais Motschulsky, but not Tribolium castaneum Herbst. No significant differences were found in mortality of the adults of the rusty grain beetle when exposed at different temperatures ranging from 15−35°C. Gas chromatography-mass spectrometry (GC–MS) analysis showed that the main components of the eluent of star anise powder were trans -anethole (62.60%), estragole (23.70%), linalool (3.66%) and d -limonene (2.15%). In the fumigation test using synthetic standards of these four chemicals, only trans -anethole showed effective biological activity with exposure to 30 mL/L trans -anethole for 24 h resulting in 100% mortality of rusty grain beetle adults. Estragole did significantly enhance fumigant efficiency of trans -anethole. We further found that trans -anethole affects the beetles acetylcholinesterase activity, which was inhibited and decreased by 64.48% within 24 h. The results therefore show that trans -anethole, the major component of star anise volatiles contributes to its fumigant toxicity against C. ferrugineus by, at least partly, affecting its insect nervous system. Hence, star anise or its biologically active substances show very good potential to be used as a botanical insecticide to control C. ferrugineus. [ABSTRACT FROM AUTHOR]

Monoterpenes are the major components of essential oils from many aromatic plants, partly contributed to the insecticidal properties of essential oils. In this study, the fumigation activity of 40 pure monoterpenes against fruitfly, Drosophila melanogaster , were evaluated. Results from fumigation tests revealed that terpinolene, 3-carene, eugenol, thymol, carvacrol, isoeugenol, citral, (±)-citronellal, cuminaldehyde, (−)-verbenone, and (+)-pulegone exhibited strong fumigation activity against D . melanogaster . In addition, the (±)-citronellal and (+)-pulegone (aldehydes and ketones) were the most toxic monoterpenes to D . melanogaster with LC 50 values of 0.015 and 0.02 μl/L, respectively. Oxygenated monoterpenes were found to be with higher toxicity as compared with monoterpene hydrocarbons. The present results indicated that (±)-citronellal and (+)-pulegone exhibit a potential for the development of new botanical insecticides against the D . melanogaster , suggesting that further studies of a number of medically important dipterans might be warranted. [ABSTRACT FROM AUTHOR]

• Spearmint EO and its major constituents have toxic effects on R. dabieshanensis. • The toxic efficacy increased with increasing temperature against R. dabieshanensis. • Carvone highly synergized the toxicity of limonene and dihydrocarvone. • All treated termite showed the increased activity of detoxifying enzymes. • Spearmint EO and its constituents inhibited activity of AChE in vivo and in vitro. This study evaluated the chemical components of spearmint essential oil, and determined individually the efficacy of spearmint EO and its major constituents, and their mutual binary combination against Reticulitermes dabieshanensis. We also evaluated the activities of esterases (ESTs), glutathione S-transferases (GST) and Acetylcholinesterase (AChE) enzymes in treated insects. GC–MS analysis showed that the major constituents of spearmint EO were carvone (52.25 %), limonene (19.78 %), and dihydrocarvone (11.1 %). In fumigant toxicity assay, the spearmint EO achieved a LC 50 value of 0.194 μl/L. The three major constituents, carvone, dihydrocarvone, and limonene were most effective against R. dabieshanensis , with LC 50 values of 0.074, 0.155, and 2.650 μl/L, respectively. The toxicity assay of binary mixtures of carvone + dihydrocarvone, carvone + limonene and limonene + dihydrocarvone in all the used ratios showed the three major constituents exhibited synergistic effects against R. dabieshanensis. Spearmint EO and its major constituents showed significantly stronger insecticidal efficacies at the high temperature, with rapid insecticidal action. The increased activity of ESTs and GST were observed, but with the decreased activity of AChE in all treatments. In vitro experiments, all treatments showed significant inhibition of AChE activity, except for dihydrocarvone, with IC 50 values were 0.871, 2.405, 2.653 and 4.343 μl/mL for limonene, carvone, carvone + limonene and carvone + dihydrocarvone, respectively. The results showed that the insecticidal efficacy of spearmint EO can be attributed to the major component, possibly carvone, with strong AChE inhibition properties. Hence, spearmint EO and its bioactive constituents have the potential to be used as new environmentally safe insecticides for controlling R. dabieshanensis. [ABSTRACT FROM AUTHOR]