The main chemical constituents of agarwood are sesquiterpenes and chromones, which can be divided into different categories depending on their molecular skeletons. Agarwoods are obtained from different plant species: Aquilaria sinensis, A. malaccensis, A. crassna, and A. subintegra. In this review, we systematically summarized the structures of main compounds isolated from agarwoods originating from four main species. We structurally classified all the components into 11 different types and summarized the number of compounds in each type. Different and identical components were obtained by enumerating the chemical compositions of the different species. Knowledge regarding the chemical constituents of agarwoods of different species will aid understanding of the chemical compositions of agarwoods and will subsequently identify similar compounds that can serve as standards for quality control to provide a reference for future studies on agarwoods from different species and to increase their usefulness.
Agarwood is a resinous portion of Aquilaria trees, a genus belonging to the family Thymelaeaceae. Agarwoods have wide uses in traditional medicine, for example, as aphrodisiacs, sedatives, cardiotonics, and carminatives, as well as in the relief of gastric problems, coughs, rheumatism, and high fever. In addition, agarwoods are present in important spices and are also used as incense. Agarwood is known as ‘chenxiang’ in Chinese and ‘aloeswood’, ‘agalloch’, ‘eaglewood’, ‘jinkoh’, ‘gaharu’, and ‘kanankoh’ in other parts of the world.
Approximately 15 species of Aquilaria are well known for their production of fragrant heartwood, also known as gaharu, aloeswood or agarwood. Wounding of the tree appears to be essential for the initiation of gaharu production, and fungal infection is likely to enhance the process. According to Eurlings et al., the following nine Aquilaria species produce gaharu: A. beccariana, A. crassna, A. filaria (Oken), A. hirta, A. khasiana, A. malaccensis, A. microcarpa, A. rostrata and A. sinensis; these are mainly sourced from India, Southeast Asia, Papua New Guinea, and China (chiefly in Hainan and Guangdong).
Sesquiterpenoids and phenylethyl chromone derivatives are the principal compounds in the oleoresin of agarwood, which are mostly found in the species Aquilaria, A. malaccensis, A. agallocha, A. sinensis, and A. crassna.
1/Sesquiterpenes of agarwood
Agarwoods contain various types of sesquiterpenes, which can be divided into several categories depending on their molecular skeletons. Some examples of these sesquiterpenes are agarofurans, agarospiranes, eudesmanes, eremophilanes, guaianes, candinanes, and prezizanes . Other compounds are also present in small amounts.
See sesquiterpenes compound at https://www.researchgate.net/publication/322203968_Sesquiterpenes_and_Chromones_of_Agarwood_A_Review
2/Chromone derivatives in agarwood
Chromone derivatives are other major constituents of agarwoods. They have been obtained from only a few plant species, including Eremophila georgei, Bothriochloa ischaemum (Gramineae), and agarwoods originating from Aquilaria spp. (Thymelaeaceae). 2-(2-Phenylethyl)chromone derivatives are the characteristic components of agarwoods, and more than 40 such derivatives have been found in agarwoods belonging to different species. Depending on the molecular skeleton, chromones can be divided into 2-(2-phenylethyl)chromones, 5,6,7,8-tetrahydro-2-(2-phenylethyl)chromones, diepoxy-tetrahydro-2-(2-phenylethyl)chromones, and associated chromones.
See Chromone derivatives at: https://www.researchgate.net/publication/322203968_Sesquiterpenes_and_Chromones_of_Agarwood_A_Review
3/Aromatic ketones in Agarwood
4/Fatty acids in Agarwood.
EX: Hexadecanoic acid; Pentadecanoic acid; Pentadecenoic acid; Tetradecanoic acid; Octanoic acid;…