Quantitative Analysis of Kratom Alkaloids

Chloroquine, 7-hydroxymitragynine, midazolam, mitragynine, and mitragynine-d₃ were purchased from Cayman Chemical (Ann Arbor, MI, USA). The kratom alkaloids speciogynine, mitraciliatine, speciociliatine, paynantheine, and isopaynantheine were isolated and purified from Mitragyna speciosa as detailed previously [7 (link)]; all standards were >95% pure as measured by ultraperformance liquid chromatography (UPLC). Alprazolam and tert-butyl methyl ether (t-BME) were purchased from Sigma-Aldrich (St. Louis, MO, USA). Human liver microsomes (HLMs; H0604, mixed biological sex, pool of 15, lot 1010191) and human intestinal microsomes (HIMs; H0610.I, mixed biological sex, pool of 10, lot 1610314) were purchased from XenoTech, LLC (Kansas City, KS, USA). Acetonitrile and methanol were purchased from Fisher Scientific (Fair Lawn, NJ, USA). Blank human plasma (K₂EDTA, mixed biological sex, pooled, lot HMN99236) and whole blood (K₂EDTA, mixed biological sex, pooled, lot HMN541526) were purchased from BioIVT (Westbury, NY, USA). All other chemicals and reagents were analytical grade.