Chemical Constituents of Essential Oils of Cymbopogon distans from Two Producing Areas during Different Storage Periods

Abstract

The essential oils of Cymbopogon distans from Gansu and Sichuan were obtained by dynamic headspace method and analyzed by gas chromatography and mass spectrometry for different storage periods (1 month, 3 months, 6 months, and 12 months). The types of chemical constituents of essential oil from Gansu C. distans with different storage periods are alkanes, esters, amides, and ketones. In addition to the above four, compounds of Sichuan C. distans essential oil also include aldehydes, benzenes, and carboxylic acids. Alkanes of the essential oil collected from the two regions increased with storage time. After 12 months of storage, amides was the largest in the essential oil of Gansu, while that of Sichuan was ketones. The essential oils of Gansu and Sichuan C. distans were identified 24 and 27 compounds, respectively. Among these compounds, hexadecane and heneicosane are the major compounds inessential oil of Gansu and Sichuan C. distans , respectively. Dibutyl phthalate, hexacosane, and heneicosane were produced in the two places in the same period, which can be used to identify the chemical fingerprint of C. distans. Six differential metabolites (nonadecane, heptadecane, octadecane, dibutyl phthalate, 2-methyl-hexacosane, and heneicosane) can be used as a basis for judging the origin of C. distans capillary column. Programmed temperature: the initial temperature was 50℃ for 3 minutes, 5°C/min to 210°C for 3 min, and then 15°C/min to 280°C for 3 min; Injector temperature was 250℃; The carrier gas was helium; The flow rate was 1.0 mL/min. The shunt ratio was 30:1; the injection volume was 500μL. Mass spectrometry conditions: ion source temperature (230℃), quadrupole tem perature (150℃), interface temperature (280℃). The ionization mode is electron bombardment ion source. Electron energy was at 70 eV. Mass number (m/z) scanning range from 30 to 600. Solvent delay was 3 min. RI values were obtained by comparing with mass spectra of n-alkanes under the identical conditions. The of the by