Study On Fragrant Constituents In Agarwood 'Qi-Nan' And Quality Evaluation Of Agarwood

'Qi-Nan'is regarded as the highest quality and precious kind of agarwood. In order to identify the fragrant components of agarwood "Qi-Nan", and to determine the similarity and difference of the chemical constituents in "Qi-Nan" and other usual agarwoods, we investigated the chemical constituents of'Lv Qi-Nan', one type of high quality agarwood 'Qi-Nan'collected in Huidong, Guangdong and led to the isolation of forty compounds. Their structures were identified by physicochemical properties and spectral data (UV, IR, MS,1D and2D NMR) as qinanone A-F (1-6),2-(2-phenylethyl)chromone (7),2-[2-(4-methoxyphenyl)ethyl]chromone (8),6-hydroxy-2-(2-phenylethyl)chromone (9),6-hydroxy-2-[2-(4-methoxyphenyl)ethyl]chromone (10),6-hydroxy-2-[2-(2-hydroxy-phenyl)ethyl]chromone (11),6-hydroxy-2-[2-(3-methoxy-4-hydroxyphenyl)ethyl] chromone (12),6-hydroxy-2-[2-(3-hydroxy-4-methoxyphenyl)ethyl]chromone (13), qinanone G (14)?2-[2-hydroxy-2-(4-hydroxyphenyl)ethyl]chromone (15),2-[2-hydroxy-2-(4-methoxyphenyl)ethyl]chromone (16),6,7-dimethoxy-2-(2-phenylethyl) chromone (17),8-Hydroxy-2-(2-phenylethyl)chromone (18), qinanol A-E (19-23), sinenofuranol (24), qinan lactone (25), qinan-guaiane-one (26),4-epi-10-hydroxyacoronene (27),4-epi-15-hydroxyacorenone (28), a-kessyl alcohol (29),4-hydroxyl-baimuxinol (30),7?-H-9(10)-ene-11,12-epoxy-8-oxoeremophilane (31),7a-H-9(10)-ene-11,12-epoxy-8-oxoeremophilane (32), Neopetasane (33), cis-7-hydroxycalamenene (34),(3(3)-olean-12-ene-3,23-diol (35), hexadecanoic acid,2,3-dihydroxypropyl ester (36), ?-sitosterol (37),1-hydroxy-1,5-diphenylpentan-3-one (38),(5R,6R,7S,8R)-5,6,7,8-tetrahydro-5,6,7,8-tetrahydroxy-2-(2-phenylethyl)-4H-chromen-4-o ne (39), and (5R,6R,7S,8R)-2-(phenylethyl)-6,7,8-trihydroxy-5,6,7,8-tetrahydro-5-[2-(2-phenylethyl)chromonyl-6-oxy] chromone (40).Among the forty isolated compounds, twenty were2-(2-phenylethyl)chromone derivatives (1-18,39-40); sixty were sesquiterpenes, one was triterpene, one was phenol, one was fatty acid, one was sterol. Compounds1-5and14-16were new2-(2-phenylethyl)chromone derivatives. Compounds19-23,25-28,30-32were new sesquiterpenes. Thirty of the sesquiterpenes isolated were fragrant and were considered as the contributive components of fragrance of 'Qi-Nan' without burning. Two2-(2-phenylethyl)chromones were considered as the contributive components of fragrance of 'Qi-Nan' when burning, since being heated, they could be pyrolyzed to generate aromatic compounds.The acetylcholinesterase (AChE) inhibitory activity of the2-(2-phenylethyl)chromone derivatives and sesquiterpenes isolated were tested by Ellman's method, and the results showed that most of the chromones and sesquiterpenes exhibited inhibitory activity.The characteristics of MS spectra of the2-(2-phenylethyl)chromones were analyzed and summarized to propose the cleavage rules, which provided scientific basis for rapid identification of these2-(2-phenylethyl)chromones in agarwood by MS spectra. Based on these rules proposed, the chemical components of five types of agarwood'Qi-Nan'were analyzed by GC-MS. Comparison of the chemical components of the five types of agarwood 'Qi-Nan' with that of 'Qi-Nan' from Vietnam conducted by foreign scholars, led to the summarization of the main similarity and difference of the chemical constituents in "Qi-Nan" and other usual agarwoods, in'Qi-Nan'from China and 'Qi-Nan' from Vietnam, and then provided scientific evidence for the identification of high quality agarwood and quality evaluation of agarwoods.