Investigation of the volatile constituents of different Gynura species from two Chinese origins by SPME/GC-MS.

GC-MS analyses of the volatile constituents obtained by solid phase microextraction (SPME) of two Gynura species, i.e., G. divaricata and G. bicolor, collected from Nanjing and Nanping areas in the east of China, enabled the identification of more than 50 different components. Generally, a higher contents of sesquiterpene compounds such as beta-caryophyllene, alpha-caryophyllene and alpha-copaene were found in G. bicolor than in G. divaricata, regardless of their origin. Qualitatively, the detected major volatiles of G. bicolor and G. divaricata originating from Nanjing were the same, i.e., beta-caryophyllene, alpha-caryophyllene, alpha-copaene, alpha-pinene and beta-pinene. The volatile profile of a third species, G. medica, also originating from Nanjing was different with sesquiterpenes gamma-cadinene, beta-caryophyllene, elixene and monoterpene limonene as the major components. The volatile profiles of G. bicolor and G. divaricata originating from Nanping were more diverse. For both species beta-caryophyllene, alpha-copaene and limonene were the major volatiles, but G. bicolor also produced gamma-caryophyllene and carvone as major constituents, whereas for G. divariata o-cymene was detected. Overall, these results indicate that the biosynthesis of volatiles by Gynura species is not only species related, but is also possibly influenced by the local environmental conditions of growth.