山胡椒精油及其成分之生物活性

Bioactivities of Essential Oils and Their Components from Litsea cubeba（Lour.）Pers.

謝君君(Chun-Chun Hsieh)

指導教授 ： 顏才博

國立屏東科技大學/農學院/熱帶農業暨國際合作系所/碩士(2007年)

https://doi.org/10.6346/NPUST.2007.00058

摘要

山胡椒Litsea cubeba（Lour.）Pers.屬樟科小喬木，味道類似胡椒與薑的綜合。本實驗目的為評估山胡椒精油與主要成分在抗真菌、植物相剋作用及抗氧化活性之潛力。以水蒸氣蒸餾法萃取葉部、果實與枝條之精油，收率分別為1.91、4.82及0.77%，經氣相層析/質譜儀（GC/MS）。葉部精油的主要成分為桉葉醇（Eucalyptol）約佔有33.5%，果實和枝條精油的主要成分則分別為檸（Citral）55.4% 和香茅醛（Citronellal）15.4%。本實驗以木材腐朽菌、樹木病原真菌及黴菌行生物分析，結果顯示果實精油的抗菌活性最強，對四種木材腐朽菌之半數抑制濃度(IC50)範圍為23.3~113.4 μg/ml，對四種林木病原真菌之IC50範圍為62.6~508.0 μg/ml，而對三種常見黴菌亦以果實精油之活性最佳，IC50範圍為82.4~179.9 μg/ml。精油之主要化學成分則以果實精油中之檸檬醛（Citral）的抗真菌效果最佳，對木材腐朽菌、林木病原真菌及黴菌之IC50範圍分別42.3~75.4 μg/ml、62.0~162.6 μg/ml和192.5~318.4 μg/ml。
為探討Citral之抑菌機制，本實驗以掃描式電子顯微鏡（Scanning Electron Microscope）對經檸檬醛處理後之菌絲體做初步觀察。結果發現，經處理之菌絲皆呈現形變、皺縮和扭曲之現象，由此推論，抑菌機制可能是檸檬醛改變細胞壁結構，使其功能喪失，進而導致細胞質流失或外物進入細胞中，破壞細胞生理而致凋亡。
抗氧化活性方面，主要評估各部位之精油、熱水抽出物和酒精抽出物清除DPPH自由基之活性與螯合亞鐵離子的能力。葉、果實和枝條精油清除DPPH自由基之效果並不顯著，但枝條熱水抽出物和葉部乙醇抽出物則效果極佳，半數有效濃度（EC50）分別為18.7和25.3 μg/ml。至於螯合亞鐵離子能力方面，精油、熱水抽出物和乙醇抽出物雖有螯合亞鐵離子能力，但效果並不突出。
植物相剋作用方面，葉、果實及枝條精油以小白菜（Brassica chinensis）與萵苣（Lactuca sativa）種子進行莖部和根部生長分析。結果發現枝條精油對小白菜和萵苣的抑制較佳，而檸檬醛和香茅醇則為主要之植物相剋活性成分，其中香茅醇效果最強，對於小白菜與萵苣幼根生長之半數抑制濃度（IC50）皆小於200 μg/ml。綜合以上結果，山胡椒果實精油中之檸檬醛具極佳的抗真菌活性，而香茅醇則具強烈的植物相剋活性，同時枝條熱水抽出物與葉部乙醇抽出物皆呈現不錯之清除自由基能力，在此三種活性方面具有值得開發利用之潛力。

關鍵字

植物相相剋作用 ； 抗真菌活性 ； 抗氧化活性 ； 檸檬醛 ； 山胡椒

並列摘要

Litsea cubeba（Lour.）Pers. is a small tree with ginger-spicy fruits in the Lauraceae family. It is native to China, Indonesia, Taiwan and other parts of Southeast Asia. The purposes of this study are to evaluate the antifungal activities and allelopathy potential of essential oils and their major compounds extracted from the leaves, fruits and twigs of L. cubeba. In addition, antioxidant activities were also evaluated for essential oils, hot water extracts and ethanol extracts from the leaves, fruits and twigs. Essential oils were extracted by steam distillation, and their chemical compositions were analyzed by GC/MS. The results of GC/MS showed that the dominated volatile compounds of leaf, fruit and twig essential oil are eucalyptol (33.5%), citral (55.4%) and citronellal (15.4%), respectively. Three types of fungi, wood decay fungi, tree pathogenic fungi and molds were used in the antifungal tests. The results of antifungal tests showed that fruit essential oil processed the strongest antifungal activity against wood decay fungi, tree pathogenic fungi and molds with the ranges of 50% inhibitory concentrations (IC50) of 23.3-113.4 µg/ml, 62.6-508.0 µg/ml and 82.4-179.9 µg/ml, respectively. Citral, the most abundant compound in fruit essential oil, also processed excellent antifungal activities with the ranges of IC50 values of 42.3-75.4 µg/ml, 62.0-162.6 µg/ml and 192.5-318.4 µg/ml against wood decay fungi, tree pathogenic fungi and molds, respectively. Morphological alteration of fungal hyphae treated with citral was examined by Scanning Electron Microscope. Structural alteration of fungal hyphae treated with citral was found, indicating that cell wall permeability might be dramatically changed, resulting in the dysfunction of fungal cells. Allelopathy potential was investigated in vitro by examining the inhibitory effect of essential oils and their compounds on the growth of Brassica chinensis and Lactuca sativa. Results indicated that twig essential oil processed the highest allelopathy potential among three oils, and citronellol effectively inhibited the radical growth of B. chinensis (IC50 < 200 µg/ml) and L. sativa (IC50 < 200 µg/ml). Antioxidant tests were carried out by DPPH free radical scavenging and ferrous ion chelating assays. All three essential oils, hot water extracts and ethanol extracts revealed weak ferrous ion chelating activities, but twig hot water extract and leaf ethanol extract performed excellent DPPH free radical scavenging ability with the 50% effective concentration (EC50) of 18.7 and 25.3 µg/ml, respectively. In this study, L. cubeba demonstrated outstanding antifungal activities, phytotoxicity and excellent free radical scavenging capabilities. It is worthy of further study to develop as environmentally-friendly fungicides, herbicides or even health supplements.

並列關鍵字

Allelopathic ； Antifungal activity ； Antioxidant activity ； Citral ； Litsea cubeb

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