貝殼杉葉部精油之化學成分與生物活性研究

Abstract

貝殼杉屬 (Agathis) 植物主要分布於東南亞以及南半球，於民俗療法中具有舒緩疼痛功效，在前人研究中具有抗菌、抗真菌與抗瘧疾活性，然而其他的生物活性並無相關記載。此外，貝殼杉 (Agathis dammara) 為貝殼杉屬中少數分布於北半球的物種之一，因此本研究為探討貝殼杉是否具有其他生物活性，收集貝殼杉新鮮葉子後利用水蒸餾法 (hydrodistillation) 萃取貝殼杉葉部精油後，以氣相層析質譜儀分析精油化學成分，得知精油成分以 sesquiterpenoids 為主，依化學結構分類則以 cadinane 骨架的化合物為最多。生物活性方面，利用貝殼杉精油作為試樣測試其對黑色素生成抑制活性、黃嘌呤氧化酶抑制活性、抗病媒蚊幼蟲以及海蝦 (Artemia salina Leach) 致死試驗，在黑色素生成抑制活性探討上，包含測試酪胺酸酶抑制活性 (in vitro) 與斑馬魚 (Danio rerio) 黑色素定量試驗 (in vivo)，結果顯示貝殼杉精油可抑制酪胺酸酶作為 diphenolase 之活性，且在斑馬魚黑色素定量試驗中，於 50 μg/mL 濃度時，可以減少斑馬魚體上的黑色素；然而在黃嘌呤氧化酶試驗中，可知貝殼杉葉部精油並非有效抑制尿酸生成的抑制劑。貝殼杉精油在抗病媒蚊幼蟲試驗中，對埃及斑蚊 (Aedes aegypti) 幼蟲具有良好毒殺效果。使用海蝦作為模式生物，貝殼杉精油可有效毒殺海蝦。經過上述活性評估過後，可知貝殼杉精油作為黑色素抑制劑與天然病媒蚊殺蟲劑具開發潛力。

Agathis species are widely distributed around Southeast Asia and the Southern hemisphere. Traditionally, Agathis species were considered to be a remedy for aches. Besides ache treatment, Agathis species possess antibacterial, antifungal, and antimalarial activities. However, related studies for other bioactivities of the species, especially of Agathis dammara, are limited. Because of the lack of study on the bioactivities of A. dammara, this study aims to investigate the chemical composition of A. dammara leaf essential oil (ADEO) and to explore its bioactivities. In the first part of the study, the chemical composition of ADEO was analyzed using Gas Chromatography-Mass Spectrometry (GC-MS). The results showed that the major constituents of ADEO were sesquiterpenoids characterized by the cadinene skeleton. To investigate bioactivities of ADEO, four activities, including antimelanogenic effect, xanthine oxidase inhibitory activity, mosquito larvicidal activity, and brine shrimp (Artemia salina Leach) lethality, were analyzed. In the antimelanogenic effect evaluation, both in vitro and in vivo assays were carried out. According to the result from in vitro assay, ADEO could inhibit tyrosinase activity when the substrate was 3,4-dihydroxyphenylalanine (L-DOPA). Furthermore, ADEO displayed antimelanogenic effect because ADEO could reduce zebrafish (Danio rerio) pigmentation at the concentration of 50 μg/mL. As for assessments of mosquito larvicidal activity and brine shrimp lethality, ADEO could work effectively against Aedes aegypti larvae and brine shrimp. However, ADEO cannot present xanthine oxidase inhibitory activity in the xanthine oxidase inhibition assay. According to these findings, ADEO could have a potential to be a natural whitening agent and a mosquito larvicide.