摘要
沉香於神農本草經中被載明作為鎮靜及鎮痛作用的藥物，在燃燒時所發出的香味容易使人進入安定的狀態。文獻指出沉香的藥理活性成分對於抗過敏、抗癌、抗氧化、抗發炎、抗菌以及抗憂鬱等具有功效，而沉香精油對腦部之影響推測與GABA或丘腦-垂體-腎上腺軸 (HPA Axis) 有關。沉香是瑞香科 (Thymelaeaceae) 沉香屬 (Aquilaria) 的植物樹脂，不同類型的沉香香味有很大的差異，而其中最頂級的沉香統稱為棋楠沉香，其香氣特殊、持久而且十分強烈，燃燒時會產生不同香味變化。學術上對於沉香的研究，發現倍半萜類以及2-(2-苯乙基) 色酮類 (2-(2-phenylethyl) chromone) 衍生物為沉香中的主要成分，其中2-(2-苯乙基) 色酮類更是沉香的指標成分，其特性為低極性，僅能以有機溶劑萃取後分析。在加熱沉香後吸附其氣味進行的2篇前人研究中，2-(2-苯乙基) 色酮類衍生物僅在較貴的沉香香氣中被偵測到，但目前為止，所有成分或研究方法都無法準確表達成分與沉香價值的相關性。本研究主要目的是為了瞭解沉香香氣是如何達成安定的藥理功效。實驗用加熱沉香香氣連續讓小鼠吸入香氣一週後，取出小鼠的腦部進行基因表現分析，以藥理分析基因變化來確認沉香香氣安定效果的途徑。由於沉香缺乏標準品，而沉香價值主要以氣味來決定，因此本研究先建立氣味成分的分析方法：使用頂空系統 (Headspace) 加熱沉香後，將氣味成分直接以GC-MS/MS進行成分分析，再以7種不同沉香 (包括台灣1種、越南2種、柬埔寨1種、寮國1種、印度1種、斯里蘭卡1種) 進行三重複的成分分析比對。分析氣味成分結果顯示：沉香的指標成分2-(2-苯乙基) 色酮，結果顯示此成分僅出現於棋楠 (26.19 ± 1.00, area%) 及台灣沉香 (25.68 ± 0.70, area%) 中。再以群集分析 (cluster analysis) 方法，進行各種沉香氣味的氣相指紋圖譜群集類型分析，結果顯示棋楠與所有的沉香都屬於同一個群集中，而所有沉香與印尼鷹木是完全不同的2群存在。此結果顯示，棋楠沉香燃燒加熱後的氣味不僅在成分上具有代表性，統計分析也顯示棋楠於8種沉香中具有代表性。後續以棋楠的香氣進行動物試驗分析，將棋楠加熱後產生的氣味連續導入小鼠薰蒸罐中，進行每天45分鐘，連續一週的薰香試驗，最後一天試驗後犧牲小鼠取腦進行RNA表現量分析。香氣薰蒸後小鼠的基因分析與血清分析結果顯示：沉香香氣影響了4個標靶路徑 (GABA、Serotonin、Dopamine、long-term derpession)，且血清素含量也有提升。分析血清素(serotonin)相關的表現基因，發現其深合成基因Tph1表現量也有提升。除了srotonin表現量提升之外，Crhr2以及Chrnd的表現量也有顯著提升。已知Crhr2基因表現量提升後主要為抑制HPA Axis的活化，而HPA Axis在脊椎動物中主要讓動物處緊張狀態，能隨時快速反應外來壓力。於人體中，HPA Axis長時間活化的結果可造成包括情緒紊亂、焦慮、躁鬱、失眠、慢性綜合疲勞症等問題。本研究結果顯示，長期吸入沉香的香味會直接舒緩動物體對壓力的反應，推測其主要機制包括提升血液中血清素含量以及腦部Crhr2基因表現量來達成效果。
並列摘要
Agarwood, whose medicinal values are discussed in The Classic of Herbal Medicine (Shen-nung Pen-tsao Ching), is a sedative and analgesic drug. Its scent emitted from heat induces people to enter a stable state. It is used in traditional medicines from various countries for various conditions, including treating rheumatoid joint diseases, body pain, diarrhea and other related diseases. Modern research literature found that the compounds in agarwood have anti-allergy, anti-cancer, anti-oxidation, anti-inflammatory, anti-bacterial and anti-depression properties. There is speculation that the effect of agarwood essential oils on the brain is related to the GABA related pathway or the Hypothalamic–pituitary–adrenal axis (HPA axis). Agarwood refers to the resin produced by the Aquilaria genus (Thymelaeaceae), which is caused by external forces. The odor of different subtypes of agarwood differs considerably, presumably due to the different composition of resin after the plant is injured. The best agarwood is called kynam agarwood, which produces a pronounced odor even before heating and burning. The fragrance is long-lasting and very intense, producing a range of nuanced odors as it burns. Further analyses of agarwood in organic solvents, water vapor extracts, or essential oils via gas chromatography coupled with mass spectrometry (GCMS) found that sesquiterpenes and 2-(2-phenylethyl)chromone are major compositions of agarwood. The 2-(2-phenylethyl)chromone is an indicator component of true and false agarwood, and 2-(2-phenylethyl)chromone derivatives are detected in more expensive agarwood in two studies that observed the absorption of scent after heating the agarwood. So far, all ingredients or research methods have not been able to accurately express the correlation between ingredients and the value of agarwood, and standards for agarwood research are lacking.The main purpose of this study is to understand how agarwood odor achieves pharmacological sedative effect. The study's pharmacological activity analysis of agarwood used the incense smoke produced by heating typical agarwood for inhalation, then analyzed the sedative effect in the central nervous system. To induce the normal pharmacological effect of agarwood, typical agarwood was chosen for the study. The selection of typical agarwood is based on HS-GC/MS-MS and static analyses of incense smoke chemical composition. There are 7 different grades of agarwood that were analyzed, including Taiwan (1), Vietnam (2), Cambodia (1), Laos (1), India (1), Sri Lanka (1) by three replicates. Analysis results of 2-(2-phenylethyl)chromone, the major component of agarwood, showed that this it only appears in kynam (26.19 ± 1.00, area%) and Taiwan agarwood (25.68 ± 0.70, area%). GC fingerprint similarity analysis of various agarwood odors was carried out by PCA statistical analysis method (cluster analysis). The statistical results showed that kynam was related to all types of agarwood, while Indonesian eaglewood is completely different. This result shows that the scent of heated kynam is not only representative of the composition, but also shows statistical analysis representant in 8 kinds of agarwood.The animal experiment was carried out with kynam smoke. Kynam was heated and the smoke was continuously pumped into the mice chamber for inhalation. Inhalation was set for 45 minutes per session, once per day, for 7 consecutive days. After the 7-day inhalation period, the mice were terminated. The brains were studied via RNA microarray and the serotonin in sera were analysis. RNA profiling showed that the pharmacological activity of agarwood odor mainly increased the expression of Crhr2 and Chrnd gene, which is different from the four known target pathways. Crhr2 expression is mainly the dysregulation of the hypothalamic-pituitary-adrenal axis (HPA Axis) activity. The serotonin levels were found increase in sera, and serotonin synthesis key gene Tph1 expression also increase. These results together demonstrate that agarwood incense smoke might exhibit sedative effects via the increase of serotonin levels and dysregulation of the HPA axis in mice, thereby inducing a pharmacological sedative effect.