基于沉香形成机理对“奇楠”沉香真伪鉴定的方法学研究

Agarwood is the resinous, fragrant and highly valuable wood produced primarily by Aquilaria tree. In a natural environment, agarwood forms only when Aquilaria tree affected by certain external factors, such as lightning strike, animal grazing, insect attack or microbial invasion, typically around wounded or rotting parts of the trunk. Agarwood formation occurs slowly and infrequently in old trees. A agarwood formed usually with ten years in a tree. What’s more, the high quality agarwood need hundreds years’ formation time and usually called kyara-agarwood, its price is several ten thousand per gram. But now, the supply of agarwood from wild sources is far less than market demand. The value of agarwood shipped out of Singapore alone each year has been estimated to exceed $1.2 billion..Because of its immense value and rarity, indiscriminate cutting of trees and overharvesting in hope of finding the treasured agarwood or kyara-agarwood has led to the depletion of wild Aquilaria trees. All species of Aquilaria have been placed on the Appendix II list of the CITES. What’s more, the lack of effective identification method for false kyara-agarwood is another severe challenge, which become a rampant and is affecting trades or deals on the agarwood market. Up to now, there does not any standard identification standard for kyara-agarwood throughout the whole business and consumption. Therefore, a feasible identification method for false agarwood or kyara-agarwood must be established as soon as possible..In our previous research, we innovatively introduced and confirmed the hypothesis of agarwood formation that induced by defense response, and then preliminary explained the mechanism of agarwood formation in Aquilaria sinensis. Once the Aquilaria tree was wounded, it will be inducing and metabolizing benzylacetone, sesquiterpenoids and 2-(2-phenylethyl) chromone derivates. These characteristic compounds are participating in the formation of thylose in the secondary xylem, and occluding the vessel element of wood fiber. Then, a resin-layer is forming between the wounded surface and healthy sapwood to resist the further injure from the external factors, is called as agarwood. Thus, those characteristic compounds and microstructure of xylem are the proofs of agarwood formation..Therefore, this research is planning to verify and demonstrate the DNA barcode of Aquilaria tree, characteristic compounds, xylem microstructure as the identification characteristics of kyara-agarwood. What’s more, the false kyara-agarwood will be compared with and identified from the genuine agarwood according to the difference in the DNA barcode, characteristic compounds and xylem microstructure. Based on those identify-evidences, a feasible method and theory for the identification of false agarwood or kyara-agarwood could be established finally.

沉香为名贵药材和香料，国内、国际市场需求量巨大，但因资源濒危、供不应求导致价格与日俱增。高品质沉香需要数十年甚至更长时间才能形成，其中一类品质较高被称为“奇楠”沉香的价格高者可达数万元一克。由于沉香高额利润的诱惑和真伪鉴定方法的缺位，正滋生越来越多造假技术出现，市场上伪劣“奇楠”已经泛滥，阻碍着我国沉香产业的健康发展和复兴。因此，建立可靠的鉴定方法迫在眉睫。.课题组前期研究揭示出防御反应诱导沉香形成的机理：沉香树受到外界伤害诱导后，合成倍半萜和2-(2-苯乙基)色酮等化合物，参与形成侵填体，填充于木质部导管和木射线中，最终形成沉香。据此，本项目将研究沉香DNA条形码、木质部显微结构特征、倍半萜和2-(2-苯乙基)色酮化学成分特征及其分析技术，建立三者相结合的“奇楠”沉香鉴定方法，为“奇楠”沉香的鉴定提供依据，规范国内外沉香交易市场，保证沉香质量的安全和有效，促进中国沉香产业健康发展。

沉香为名贵药材和香料，国内、国际市场需求量巨大，但因资源濒危、供不应求导致价格与日俱增。高品质沉香需要数十年甚至更长时间才能形成，沉香的价格高者可达数万元一克。由于沉香高额利润的诱惑和真伪鉴定方法的缺位，正滋生越来越多造假技术出现，市场上伪劣沉香已经泛滥，阻碍着我国沉香产业的健康发展和复兴。因此，建立可靠的鉴定方法迫在眉睫。.本研究结合分子生物学、分析化学和木材比较解剖学等手段分别对沉香的DNA条形码、特征性化学成分分析方法和木质部显微结构特征进行研究。改进了树脂化的沉香样品提取方法，并以ITS2作为候选条形码，构建的分子鉴定方法可很好的区分沉香属物种和非沉香属物种，可用于伪品沉香的快速精准鉴别；建立了SPME联合GC-MS分析沉香benzylacetone以及特征性倍半萜类成分agarospirol，guaiol和baimuxinal的分析方法，并将其作为沉香鉴定依据之一；采用HPLC-ESI-Q-TOF-MS法建立了沉香中4个主要2-(2-苯乙基)色酮化合物的含量测定方法，可用于对劣质沉香进行准确识别；从沉香中分离鉴定了14个色酮类成分和5个木脂素类成分，为沉香的深度开发提供了依据；发明一种基于显微鉴别法的简单可行的鉴别沉香真伪的方法；并先后建立了沉香DNA条形码鉴定方法、沉香特征性化学成分分析方法和沉香木质部显微结构特征分析方法，并将进行策略组合，建成了三者相结合的“三步法”沉香鉴定鉴定技术体系，对未知样品进行鉴定，可实现对天然形成以及各种人为造假的沉香的快速、精准鉴别，已成功应用于检验检测机构对外提供沉香鉴定服务，同时参与制定并发布了《沉香鉴定》和《沉香质量等级》等2项海南省地方标准。有望规范国内外沉香交易市场，保证沉香质量的安全和有效，促进中国沉香产业健康发展。.本项目发表论文7篇，其中SCI论文2篇，中文核心论文3篇，科技核心论文2篇；授权专利4项。