Determination of kansuiphorin C and kansuinin A in rat feces using UFLC-MS/MS and its application in the comparative excretion study on normal and malignant ascites rats.

Malignant ascites (MA) is one of the severe complications of gastrointestinal tumors, affecting the patients' survival time and quality of life. Euphorbia kansui is a commonly used toxic Chinese herbal medicine for malignant ascites. Our previous study showed that the biological and toxicological effects of kansui were closely related to the gastrointestinal tract. The ingenane-type and jastrophane-type diterpenoids are both toxic and active components of kansui. The contents of kansuiphorin C (KPC) and kansuinin A (KA) take highest accounts in each type of diterpene. Hence, in this study, the efficacy and toxicity of KPC and KA on normal rats and MA rats were firstly evaluated by serum liver enzymes (ALT and AST), oxidative damage indicators (GSH, SOD, MDA and LDH), inflammatory indexes (TNF-α, IFN-γ and IL-2) and the volume of ascites. Changes in the levels of these indices showed that although the toxicity of KPC on normal rats was stronger than KA, KPC exhibited better efficacy to the malignant ascites with no obvious side effects at the dose of 10 mg·kg. Then, accurate and reliable methods for the determination of KPC and KA in the rat feces by ultra-fast liquid chromatography coupled with MS/MS detector (UFLC-MS/MS) were established, detected by the multiple reaction monitoring mode. The chromatographic separation was conducted on an XBbridge C18 column (50 mm × 2.1 mm, 2.5 μm) using gradient elution composed of 0.1% formic acid in water and acetonitrile. The flow rate was 0.5 mL·min and column temperature was 30 °C. The method was finally applied to the comparative study on normal and malignant ascites rats given KPC and KA, respectively. Interestingly, the results showed that KPC's accumulative fecal excretion rate (normal, 19.22%±5.36%; model, 15.96%±3.47%) were much higher than that of KA (normal, 2.928%±0.741%; model, 2.835%±0.873%) at the same dose within 48 h. This suggested KPC had higher in-vivo transformations in comparison with KA, providing guidance for the further preclinical research of KPC and KA as promising compounds treating MA.