Quantification of six volatile oil constituents of Oleum Cinnamomi in rat plasma and multiple tissues using GC-MS and its application to pharmacokinetic and tissue distribution studies

Oleum Cinnamomi is the essential oil obtained from the herb Fructus Cinnamomi which is used by the Hmong people in traditional medicine for the treatment of various diseases. At present, there are a variety of marketed preparations with it as the main medicine on the market. Information regarding the in vivo process of it is lacking, which has become a bottleneck restricting its development and utilization. In view of this, a GC-MS SIM analysis method was established for the simultaneous determination of six main volatile components [eucalyptol, p-cymene, 4-carvomenthenol, 4-isopropyl-2-cyclohexenone, α-terpineol, and 2-(4-Methylphenyl)-propan-2-ol] in plasma and ten tissues of rats to study their pharmacokinetic and distribution characteristics in vivo. The pharmacokinetic results showed that the t1/2 of each index was 0.41-1.66 h, Tmax was 0.16-0.68 h, Cmax was 13.66-2015.02 ng/mL, AUC0-t was 12.84-4299.00 h·ng/mL, CLZ/F was 1750.93-107013.11 mL/h/kg. This meant that the six components could be absorbed quickly, had a short residence time, and be eliminated quickly in the body. Among them, eucalyptol has the highest degree of absorption and a larger amount of entering the body. Moreover, the Cmax and AUC0-t of the six components increased correspondingly with the increase of the dose, indicating that the concentration of Oleum Cinnamomi in the rat plasma was dose-dependent. At different time points, the six components were widely distributed with uneven characteristics in the body. The six components mainly tend to be distributed in stomach, small intestine, and liver, followed by kidney, spleen, heart, and brain, and to a lesser extent in lung, skin, and muscle. And the six components were eliminated quickly in each tissue. The pharmacokinetic process and tissue distribution characteristics of Oleum Cinnamomi were expounded in this study, which can provide scientific theory for the in-depth development and guidance of clinical drug use of Oleum Cinnamomi, and at the same time provide a medicinal material basis for the in-depth development and utilization of Oleum Cinnamomi.