Characterization and Determination of 2-2-Phenylethylchromones in Agarwood by GC-MSReport as inadecuate




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1

Key Laboratory of Biology and Genetic Resources of Tropical Crops, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China

2

Hainan Key Laboratory for Research and Development of Natural Product from Li Folk Medicine, Haikou 571101, China





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Abstract Agarwood is the fragrant resinous heartwood obtained from certain trees in the genus Aquilaria belonging to the family Thymelaeaceae. 2-2-Phenylethylchromones and characteristic sesquiterpenes are the main classes of aromatic compounds isolated from agarwood. Although there are many sesquiterpenes, relatively few 2-2-phenylethylchromones have been determined in agarwood by GC-MS. After analysis of the MS spectra of eighteen 2-2-phenylethylchromone derivatives isolated from agarwood and identified by NMR spectroscopy, together with the reported MS data and characteristic of structures of 2-2-phenylethylchromones, the MS characterization, fragmentation patterns and characteristic fragment peaks for the compounds were deduced and a table summarizing MS characterization of 2-2-phenylethylchromones in agarwood is presented. All the 2-2-phenylethylchromones previously reported in agarwood are substituted by methoxy or-and hydroxy groups, except for one compound. Due to the fact they all possess the same basic skeleton molecular weight: 250 and similar substituent groups methoxy or hydroxy groups, a formula 30m + 16n = MW − 250 is provided to calculate the number of methoxy m or hydroxy n groups according to molecular ion peak or molecular weight MW. We deduced that the characteristic fragmentation behaviors of the 2-2-phenylethylchromones are the cleavages of the CH2-CH2 bond between chromone moiety and phenyl moiety. Thus, characteristic fragment ions, such as m-z 91 C7H7, 107 C7H6+OH, 121 C7H6+OCH3, 137 C7H5+OH+OCH3 are formed by different substituted benzyl moieties, while characteristic fragment ions such as m-z 160 C10H8O2, 176 C10H7O2+OH, 190 C10H7O2+OCH3, 220 C10H6O2+OCH3×2 are formed by different substituted chromone moieties. Furthermore, rules regarding to the relationship between the positions of hydroxy or methoxy groups and the relative abundances of benzyl and chromone fragment ions have been deduced. Elucidation of how the positions of hydroxy or methoxy groups affect the relative abundances of benzyl and chromone fragment peaks is also provided. Fifteen unidentified compounds of an artificial agarwood sample analyzed by GC-MS, were preliminary determined as 2-2-phenylethylchromones by analysis of their MS characterization and by comparison of their MS spectra with those of 18 standard compounds or 2-2-phenylethylchromones reported in literature according to the above-mentioned methods and rules. This report will be helpful for the analysis and structural elucidation of 2-2-phenylethylchromones in agarwood by GC-MS, and provides fast and reliable characterization of the quality of agarwood. View Full-Text

Keywords: agarwood; 2-2-phenylethylchromone; fragmentation pattern; GC-MS agarwood; 2-2-phenylethylchromone; fragmentation pattern; GC-MS





Author: Wen-Li Mei 1,2, De-Lan Yang 1,2, Hao Wang 1,2, Jin-Ling Yang 1,2, Yan-Bo Zeng 1,2, Zhi-Kai Guo 1,2, Wen-Hua Dong 1,2, Wei Li 1,2 and Hao-Fu Dai 1,2,*

Source: http://mdpi.com/



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