Volatile oils of Aquilaria malaccensis Benth. (Thymelaeaceae) from Malaysia were obtained by hydrodistillation and subjected to detailed GC-FID and GC/MS analyses to determine possible similarities and differences in their chemical composition in comparison with the commercial oil. A total of thirty-one compounds were identified compared with twenty-nine identified in the commercial oil. The major compounds identified were 4-phenyl-2-butanone (32.1%), jinkoh-eremol (6.5%) and α-guaiene (5.8%), while the major compounds in the commercial oil were α-guaiene (10.3%), caryophellene oxide (8.6%), and eudesmol (3.2%). The results of the present study showed that more than nine sesquiterpene hydrocarbons were present, which is more than previously reported. Analysis also showed that the number of oxygenated sesquiterpenes in this study were much less than previously reported. Among the compounds detected were α-guaiene, β-agarofuran, α-bulnesene, jinkoh-eremol, kusunol, selina-3,11-dien-9-one, oxo-agarospirol and guaia-1(10),11-dien-15,2-olide.

This paper presents an overview of analysis agarwood oil and its quality grading. The review suggested agarwood oil can be graded according to their chemical properties and so that there is a common standard recognized worldwide on grading the agarwood oil. Analysis based on chemical profiles is required to ensure that agarwood oil can be classified based on their respective classes or grades where the accurate results can be measured. Conventionally, the grading of agarwood oil is performed by trained human graders (sensory panels) depends on its physical appearance such as color, odor, high fixative and consumer perception. However, this method is limited due to human nose cannot accept many samples in one time and easily get fatigues especially when dealing with continuous production. The human sensory panel also limited in terms of subjectivity, poor reproducibility, time consumption and large labour expense. These are constraining factors in increasing agarwood oil trade and market penetration.

Agarwood or gaharu is resin-impregnated wood of the tree genus Aquilaria (Thymelaeaceae). In Malaysia, the main agarwood producer is Aquilaria malaccensis and oil extracted from this species is highly priced. One of the challenges in commercializing agarwood is the lack of universal standard to classify the aromatic oils. Our present knowledge places the main aromatic compounds of agarwood oil in the sesquiterpene hydrocarbon region. In this work, we extracted agarwood oil using hydrodistillation method in the laboratory and compared with a commercial-scale extraction in the factory. We analyzed the sesquiterpene hydrocarbon region using several highly sophisticated detection systems. Using GC-FID, 12 sesquiterpene hydrocarbons were identifi ed, while another eight were determined using GC-MS. Five compounds were identifi ed in both analytical techniques: aromadendrene, α-bulnesene, α-guaiene, γ-gurjunene, and β-maaliene. Advanced analysis using GC × GC/TOFMS detected 24 sesquiterpene hydrocarbons in both laboratory and pilot scale agarwood oils. Many of the sesquiterpene hydrocarbons identifi ed provide the woody aroma to the agarwood oil. Specifi cally, α-gurjunene and α-guaiene contribute to the woody balsamic aroma, while α-copaene contributes to the spicy-wood aroma. In total, 33 sesquiterpene hydrocarbons were identifi ed from A. malaccensis in the present study, with high certainty. Results from this study can be used toward establishing a universal standard for agarwood oil from the genus Aquilaria in the global market, which is presently lacking.

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Patchouli is a plant which is native in Malaysia. It is an economic crop, planted for its essential oil. Patchouli oil has a characteristic woody scent and is used commercially as an ingredient in fragrance and cosmetic products. The average yearly consumption around the globe is around one metric ton. A marker compound responsible for the patchouli oil scent is patchoulol (C15H26O). It is the major compound in patchouli oil representing around 40–50% of the essential oil composition. The aim of this study is to simulate the patchouli oil extraction process using patchoulol as a modeled molecule in different solvents, namely acetone, ethanol, and hexane. The simulation aim is to recognize molecular interaction between patchoulol molecules with solvent molecules through hydrogen bonding and also the repulsion forces between them due to the abundance of hydrogen atoms in the patchoulol molecule. The simulation is equilibrated under moles, volume, and energy followed by moles, pressure, and temperature ensembles via molecular dynamics simulation using the Material Studio software package. The interaction in the system is analyzed through the radial distribution function to describe the structure of patchoulol in solvent solution. The rdf trend found that the interaction between patchoulol solutes is through the oxygen atom (O1P) and hydrogen (H1P) atom from the hydroxyl functional group of the patchoulol molecule. In the acetone–patchoulol and hexane–patchoulol systems, the patchoulol solutes tend to self-agglomerate indicated by first neighboring molecules in the range of 4.25 Å and 5.75 Å, respectively, while the first neighboring molecules of patchoulol solutes in the binary ethanol–patchoulol system is located at 7.75 Å. This might suggest that the patchoulol is much more soluble in ethanol then in acetone and hexane. The pattern observed in the simulations is in agreement with extraction yield results obtained from the extraction experiment.