Altintas Ayhan, Tabanca Nurhayat, Tyihák Erno, Ott Peter G, Móricz Agnes M, Mincsovics Emil, Wedge David E
J AOAC Int. 2013 Nov-Dec;96(6):1200-8. doi: 10.5740/jaoacint.sgealtintas.
Essential oils obtained by hydrodistillation (HD) and microwave-assisted HD (MWHD) of Origanum onites aerial parts were analyzed by GC and GCIMS. Thirty-one constituents representing 98.6% of the water-distilled oil and 52 constituents representing 99.6% of the microwave-distilled oil were identified. Carvacrol (76.8% HD and 79.2% MWHD) and thymol (4.7% HD and 4.4% MWHD) were characterized as major constituents in both essential oils. Separation of carvacrol and thymol was achieved by overpressured layer chromatography. HPTLC and TLC separations were also compared. Essential oils were evaluated for antifungal activity against the strawberry anthracnose-causing fungal plant pathogens Colletotrichum acutatum, C. fragariae, and C. gloeosporioides using a direct overlay bioautography assay. Furthermore, main oil components carvacrol and thymol were then evaluated for antifungal activity; only carvacrol demonstrated nonselective antifungal activity against the three Colletotrichum species. Thymol and carvacrol were subsequently evaluated in a 96-well microdilution broth assay against Phomopsis obscurans, Fusarium oxysporum, three Colletotrichum species, and Botrytis cinerea. No activity was observed against any of the three Colletotrichum species at or below 30 pM. However, thymol demonstrated antifungal activity and produced 31.7% growth inhibition of P. obscurans at 120 h and 0.3 pM, whereas carvacrol appeared inactive. Thymol and carvacrol at 30 pM showed 51.5 and 36.9% growth inhibition of B. cinerea at 72 h. The mechanism of antibacterial activity was studied in a bioautography-based BioArena system. Thymol and carvacrol showed similar inhibition/killing effect against Bacillus subtilis soil bacteria; the action could be enhanced by the formaldehyde generator and transporter copper (II) ions and could be decreased in the presence of L-arginine, a formaldehyde capturer. Results indicated that Origanum essential oils and its major components thymol and carvacrol appear to generate antimicrobial activity through a mechanism of action where formaldehyde and its reaction products are produced.
采用气相色谱（GC）和气相色谱 - 质谱联用（GC - MS）对牛至地上部分通过水蒸馏法（HD）和微波辅助水蒸馏法（MWHD）获得的精油进行了分析。鉴定出了占水蒸馏油98.6%的31种成分以及占微波蒸馏油99.6%的52种成分。香芹酚（水蒸馏法中占76.8%，微波蒸馏法中占79.2%）和百里香酚（水蒸馏法中占4.7%，微波蒸馏法中占4.4%）被确定为两种精油的主要成分。通过超压薄层色谱法实现了香芹酚和百里香酚的分离。还比较了高效薄层色谱（HPTLC）和薄层色谱（TLC）的分离效果。使用直接覆盖生物自显影分析法评估了这些精油对引起草莓炭疽病的真菌植物病原体尖孢炭疽菌、草莓炭疽菌和胶孢炭疽菌的抗真菌活性。此外，随后评估了主要油成分香芹酚和百里香酚的抗真菌活性；只有香芹酚对三种炭疽菌属物种表现出非选择性抗真菌活性。随后在96孔微量稀释肉汤试验中评估了百里香酚和香芹酚对隐匿拟茎点霉、尖孢镰刀菌、三种炭疽菌属物种和灰葡萄孢的活性。在30 pM及以下浓度时，未观察到对任何三种炭疽菌属物种有活性。然而，百里香酚表现出抗真菌活性，在120小时和0.3 pM时对隐匿拟茎点霉产生了31.7%的生长抑制，而香芹酚似乎无活性。在72小时时，30 pM的百里香酚和香芹酚对灰葡萄孢分别表现出51.5%和36.9%的生长抑制。在基于生物自显影的BioArena系统中研究了抗菌活性机制。百里香酚和香芹酚对枯草芽孢杆菌土壤细菌表现出相似的抑制/杀灭作用；甲醛生成剂和转运铜（II）离子可增强这种作用，而在甲醛捕获剂L - 精氨酸存在时作用会减弱。结果表明牛至精油及其主要成分百里香酚和香芹酚似乎通过产生甲醛及其反应产物的作用机制产生抗菌活性。
