六種化學品系土肉桂葉子精油抗細菌、腐朽菌、病媒蚊幼蟲及室塵蟎活性

Abstract

本研究目的係將多種地理種源的土肉桂葉子，以水蒸餾法萃取其精油，並分析其化學成分，再利用群團分析將之分類為不同的化學品系，另外，以抗細菌、抗腐朽菌、抗病媒蚊幼蟲及抗室塵蟎等試驗評估其生物活性。9種地理種源土肉桂葉子精油的收率介於0.03%-4.69%（w/w）之間，經由氣相層析質譜儀（GC-MS）分析後得知精油的成分，可將之分為6種化學品系，分別為：樟腦型、伽羅木醇型、桂皮醛型、桂皮醛-桂皮乙酸酯型、桂皮乙酸酯型及混合型。抗細菌試驗結果顯示，以桂皮醛型土肉桂葉子精油之活性最好，比較各精油主成分之抗細菌活性，仍是以桂皮醛為最佳。抗腐朽菌試驗結果顯示，對於L. b.白腐菌及L. s.褐腐菌，以混合型、桂皮醛型及桂皮醛-桂皮乙酸酯型土肉桂葉子精油效果較好，各精油主成分則是以T-Cadinol、桂皮醛及檸檬醛較佳，比較桂皮醛相關衍生物以桂皮醛及α-Methyl cinnamaldehyde的抑制活性較好。抗病媒蚊幼蟲試驗結果顯示，以桂皮醛型及桂皮醛-桂皮乙酸酯型土肉桂葉子精油對於埃及斑蚊及白線斑蚊幼蟲的毒殺效果最佳，至於精油主成分之效果，則以桂皮醛及桂皮乙酸酯的毒殺效果較好，比較桂皮醛相關衍生物之效果，則以桂皮醛、桂皮乙酸酯、桂皮酸甲酯及α-Methyl cinnamaldehyde的活性較佳。此外，桂皮醛型土肉桂葉子精油及桂皮醛對於熱帶家蚊及白腹叢蚊均具有良好的毒殺效果。抗美洲室塵蟎試驗結果顯示，以桂皮醛型、桂皮乙酸酯型及桂皮醛-桂皮乙酸酯型土肉桂葉子精油的較佳，至於精油主成分之效果，則仍以桂皮醛及桂皮乙酸酯的活性最好。綜合上述結果顯示，桂皮醛衍生物的化學結構對於腐朽菌及病媒蚊幼蟲的抑制會造成影響，但是對於抑制細菌的效果較不明顯。

In this study, hydrodistillation was employed to extract essential oils of Cinnamomum osmophloeum's leaf from different geographical provenances. According to cluster analyses, their relative contents can be classified into different chemotypes. Furthermore, their bioactivities were evaluated by antibacterial assay, antifungal assay, mosquito larvicidal assay, and antimite assay. Yields of leaf essential oils from nine geographical provenances of C. osmophloeum ranged from 0.03%-4.69% (w/w) based on dry weight. According to GC-MS and cluster analyses, their relative contents were classified into six chemotypes-camphor type, linalool type, cinnamaldehyde type, cinnamaldehyde/cinnamyl acetate type, cinnamyl acetate type, and mixed type. The antibacterial activities of the leaf essential oils of C. osmophloeum and their constituents were investigated. Among the six chemotypes, cinnamaldehyde type had the best inhibitory effects. Meanwhile, cinnamaldehyde had the strongest antibacterial activity compared to the other constituents. From the results of antifungal assay against white-rot fungus Lenzines betulina and brown-rot fungus Laetiporus sulphureus, the leaf essential oils of mixed type, cinnamaldehyde type and cinnamaldehyde/cinnamyl acetate type had a good inhibitory effect chemotype, while T-cadinol, cinnamaldehyde and citral had better effect than others. Furthermore, cinnamaldehyde's congeners were also tested against the fungi as described above, cinnamaldehyde and α-methyl cinnamaldehyde were proven to have the better inhibitory effect. The leaf essential oil of C. osmophloeum and its constituents were also tested for mosquito larvicdal activity against fourth-instar larvae of both Aedes aegypti and Aedes albopictus. Among the chemotype examined the leaf essential oils of cinnamaldehyde type and cinnamaldehyde/cinnamyl acetate type exhibited the better activities while cinnamaldehyde and cinnamyl acetate had the best inhibitory effect compared with others. Comparison of larvicidal activity of cinnamaldehyde's congeners revealed that cinnamaldehyde, cinnamyl acetate, methyl cinnamate and α-methyl cinnamaldehyde had the mosquito larvicdal activities. Moreover, leaf essential oil of cinnamaldehyde type and cinnamaldehyde also had an excellent inhibitory effect against Culex quinquefasciatus and Armigeres subalbtus. As for the antimite assay against Dermatophagoidae farinae, the leaf essential oils of cinnamaldehyde type, cinnamyl acetate type, and cinnamaldehyde/cinnamyl acetate type showed an excellent inhibitory effect. Meanwhile, cinnamaldehyde and cinnamyl acetate still exhibited the best inhibitory effect among the other constituents. In conclusions, there is a significant relationship between chemical structures of cinnamaldehyde's congeners and antifungal activity and mosquito larvicidal activity, but no relationship exists for antibacterial activity.