| Objective:To research main volatile components and chemical natural of special aroma in fresh roots of Codonopsises by HS-GC-MS. To quantify main volatile components of Dangshen by HS-GC and to investigate the effect of plant sources, growth area and growth period on volatile components of Codonopsises and the characteristics of authentic Dangshen volatile components. To quantify main volatile components in Dangshen adventitious roots under induction with methyl jasmonate, and to research the volatile components involved in the defense response process. Methods:1. Steam distillation and head space methods were used for GC-MS to analysis the volatile components.2. HS-GC-MS method was used to analysis the volatile components in Dangshen from three plant sources and mass spectrum database was used for the structure determination. The relative percentages of components were determined by the area normalization method.3. HS-GC was used to detect the contents of n-hexanal, 2-hexenal and n-hexanol in Dangshen and to compare the contents of the three volatile components in Dangshen with different plant sources, growth area and growth period and to analysis the characteristics of authentic Dangshen volatile components.4. Liquid cultivation method was used for C.pilosula adventitious roots growth. Five groups were divided as control group(CK1), solvent control group(CK2), and methyl jasmonate group(100 μmol.L-1, 200 μmol.L-1 and 300 μmol.L-1, respectively). HS-GC was used to determine the contents of n-hexanal, 2-hexenal and n-hexanol in different groups of adventitious roots and to analysis the induced effect of methyl jasmonate on three kinds of volatile component contents to find volatile components involved in defense response in Dangshen. Results:1. The results of GC-MS analysis on volatile components of Dangshen extracted by steam distillation or headspace showed that there were differences in chemical components and the component contents between the two extraction methods. However, the main volatile components including n-hexanal, 2-hexenal, n-hexanol and 3, 3’-Diamino-4, 4’-biphenyldiol were same between the two extraction methods, which demonstrated that the headspace extraction is suitable for volatile components extraction from Dangshen.2. The results of HS-GC-MS analysis on volatile components in five commercial Dangshen products from three plant resources are as follows:117 compounds were detected in Dangshen, and 64 compounds have been confirmed, including 10 alcohols, 20 aldehydes, 14 terpenes, 3 ketones, 4 esters, 4 furans, 3 acids, 1 olefine, 1 alkane, 2 sulfides and two other compounds. The compounds confirmed from Lu Dangshen, Baitiao Dangshen, Wen Dangshen, Feng Dangshen and Banqiao Dangshen were 61, 43, 39, 45 and 46, respectively.There were 30 common volatile compounds in five commercial Dangshen products. At the same time, there were differences in volatile composition among commercial Dangshen products. However, there were 8 compounds, such as 2-isopropyl-3-methyl-3, 5-diallyl aldehyde, et al, detected only in Lu Dangshen.The volatile components with higher content in five commercial Dangshen products were mainly aldehydes(74.93%) and alcohols(11.17%). The total percentage of n-hexanal, 2-hexenal and n- hexanol was 69.25% ~ 85.30%, indicating that they were main volatile compounds in Dangshen. The percentage of n-hexanal was 42.42% ~ 59.01%, indicating that it was a major volatile component contributing to special aroma of Dangshen.In summary, Dangshen contained alcohols, aldehydes and other aromatic volatile compounds. N-hexanal was a major volatile component contributing to special aroma in Dangshen. Lu Dangshen contains the most abundant volatile components and 8 specific components.3. The results of n-hexanal, 2-hexenal and n-hexanol contents determination in Dangshen with HS-GC were as follows:The result suggested that the content of n-hexanal in Lu Dangshen was 200.41 μg.g-1 and significantly higher than that in Banqiao Dangshen, Wen Dangshen and Feng Dangshen and similar to that in Baitiao Dangshen. There was no significant difference in the content of n-hexanal in Lu Dangshen, Banqiao Dangshen and Feng Dangshen. The results showed the content of n-hexanal was mainly related to the plant source and the content of n-hexanal was higher in C. pilosula than that in others.There was no significant difference in the content of 2-hexenal among Dangshen from different plant sources and different growth periods.The content of n-hexanol in 3-year Lu Dangshen was significantly higher than that in 2-year Lu Dangshen. There was no significant difference in the content of n-hexanol among Dangshen from different plant sources.In summary, the content of n-hexanal in C. pilosula(Franch.) Nannf. was significantly higher than that in C.pilosula Nannf. var. modesta(Nannf.) L.T.Shen and C. tangshen Oliv. Therefore, n-hexanal can be used as an indicator for evaluating the quality of Dangshen.4. The results of HS-GC analysis on main volatile components in adventitious roots of Dangshen were as follows:The data showed that there was no significant difference in the content of n-hexanal between CK1 and CK2. The content of n-hexanal in adventitious roots of Dangshen induced by methyl jasmonate were higher than that of CK1 and CK2, while there was no significant difference in the content of 2-hexenal and n-hexanol among CK1,CK2 and other three experimental groups. The results indicated that ethanol had no effect on the content of n-hexanal, 2-hexenal and n-hexanol in adventitious roots of Dangshen. And methyl jasmonate had effect on the content of n-hexanal, while no effect on the content of 2-hexenal and n-hexanol.In summary, methyl jasmonate induced the content of n-hexanal in Dangshen adventitious roots and n-hexanal was likely participated in the defense response process. Conclusion:Dangshen contained a variety of aromatic volatile compounds. The total percentage of n-hexanal, 2-hexenal and n-hexanol was 69.25% ~ 85.30%, indicating that they were main volatile compounds in Dangshen. The percentage of n-hexanal was 42.42% ~ 59.01% and was a major volatile component contributing to special aroma in Dangshen. At the same time, the content of n-hexanal in Lu Dangshen was 200.41 μg·g-1 and significantly higher than that in Banqiao Dangshen, Wen Dangshen and Feng Dangshen and similar to that in Baitiao Dangshen. N-hexanal could be used as an indicator for evaluating the quality of Dangshen, and participated in the defense response process. Lu Dangshen contains the most abundant volatile components and 8 specific components. The present research indicated that special aroma was an important feature for authentic Dangshen. |
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