The Characteristic Fragrant Sesquiterpenes and 2-(2-Phenylethyl)chromones in Wild and Cultivated “Qi-Nan” Agarwood

Recently, cultivated “Qi-Nan” (CQN) agarwood has emerged as a new high-quality agarwood in the agarwood market owing to its similar characteristics, such as high content of resin and richness in two 2-(2-phenylethyl)chromone derivatives, 2-(2-phenylethyl)chromone (59) and 2-[2-(4-methoxyphenyl)ethyl]chromone (60), to the wild harvested “Qi-Nan” (WQN) agarwood. In this study, we compared the chemical constituents and fragrant components of two types of WQN agarwood from A. agallocha Roxb. and A. sinensis, respectively, with CQN agarwood and ordinary agarwood varieties. Additionally, we analyzed different samples of WQN agarwood and CQN agarwood by GC-MS, which revealed several noteworthy differences between WQN and CQN agarwood. The chemical diversity of WQN was greater than that of CQN agarwood. The content of (59) and (60) was higher in CQN agarwood than in WQN agarwood. For the sesquiterpenes, the richness and diversity of sesquiterpenes in WQN agarwood, particularly guaiane and agarofuran sesquiterpenes, were higher than those in CQN. Moreover, guaiane-furans sesquiterpenes were only detected by GC-MS in WQN agarwood of A. sinensis and could be a chemical marker for the WQN agarwood of A. sinensis. In addition, we summarized the odor descriptions of the constituents and established the correlation of scents and chemical constituents in the agarwood.