Shepherd Mervyn, Savins Dale, Dowell Ashley, Morrow Samantha, Allen Gareth, Southwell Ian
Southern Cross Plant Science, Southern Cross University, Lismore, NSW, 2480, Australia.
Chem Biodivers. 2017 Nov;14(11). doi: 10.1002/cbdv.201700278. Epub 2017 Oct 27.
Methyl eugenol is a natural phenylpropanoid compound found in a wide range of plants used for food, flavouring, cosmetics, and health-care. As a suspected rodent carcinogen, methyl eugenol may also be harmful to humans when present in significant concentrations. Consequently, its level has been restricted in some foodstuffs and cosmetics for some markets. In order to assess the potential to breed uniformly low methyl eugenol cultivars for an essential oil crop, tea tree, the source of 'Oil of Melaleuca, terpinene-4-ol type', we examine levels in individual trees (n = 30) from two geographic regions and six terpene chemotypes. Overall, methyl eugenol levels were low in this species (Mean [SD] 354 [239] ppm, n = 30), much lower than levels predicted to be of toxicological concern. Within each chemotype, there was a lack of evidence for correlations between terpenoid constituents and methyl eugenol levels. Further support for the independence of methyl eugenol and terpene biosynthesis was evident from similar mean levels in selected (Mean [SD] 586 [339] ppm, n = 12) and undomesticated Melaleuca alternifolia trees (Mean [SD] 480 [299] ppm, n = 5) with terpinen-4-ol type oils. By contrast, methyl eugenol level varied by geographic origin and chemotype. Trees from the upland region, where there is a prevalence of terpinolene type trees, had lower average methyl eugenol levels than trees from the coastal region, where there is a prevalence of terpinen-4-ol and 1,8-cineole type trees.
甲基丁香酚是一种天然苯丙素类化合物，存在于多种用于食品、调味剂、化妆品和保健品的植物中。作为一种疑似啮齿动物致癌物，当甲基丁香酚以高浓度存在时，可能对人类也有害。因此，在一些市场的某些食品和化妆品中，其含量受到了限制。为了评估为一种精油作物茶树培育甲基丁香酚含量一致较低的品种的潜力，茶树是萜品-4-醇型白千层油的来源，我们检测了来自两个地理区域和六种萜烯化学型的单株茶树（n = 30）中的甲基丁香酚含量。总体而言，该物种中的甲基丁香酚含量较低（均值[标准差]为354[239]ppm，n = 30），远低于预测的具有毒理学意义的含量水平。在每种化学型中，没有证据表明萜类成分与甲基丁香酚含量之间存在相关性。从选定的（均值[标准差]为586[339]ppm，n = 12）和未驯化的互叶白千层树（均值[标准差]为480[299]ppm，n = 5）中具有萜品-4-醇型油的类似平均含量水平，可以明显看出甲基丁香酚和萜烯生物合成的独立性。相比之下，甲基丁香酚含量因地理来源和化学型而异。在萜品油烯型茶树占优势的高地地区的茶树，其平均甲基丁香酚含量低于在萜品-4-醇和1,8-桉叶素型茶树占优势的沿海地区的茶树。
