Studies of the Toxicological Potential of Capsinoids, XII: Pharmacokinetic Study of Capsinoid-Containing CH-19 Sweet Extract in Rats

Pharmacokinetics of the main capsinoid components of CH-I9 Sweet extract (capsiate, dihydrocapsiate, and nordihydrocapsiate) were investigated in rats receiving a single gavage dose of extract containing 10 or 100 mg of capsinoids per kilogram in medium-chain triglyceride. Resultant blood levels of these capsinoids and a capsinoid metabolite, vanillyl alcohol, were measured in portal vein and systemic blood. Capsinoids were never detected. Portal compartment vanillyl alcohol concentrations and area under the plasma concentration versus time curve increased approximately with dose, whereas the time to maximum concentration of vanillyl alcohol was independent of dose (30 minutes post dosing), suggesting that precipitation in the stomach or intestines was unlikely. Vanillyl alcohol levels were just barely detectable in systemic plasma (5 minutes post dosing). Significant levels of vanillyl alcohol conjugates, sulfate, and glucuronide were detected in the systemic blood. Given that the orally administered capsinoids were never detected in the portal vein or systemic circulation, these compounds must be broken down (chemically or enzymatically) to vanillyl alcohol.