Metabolite profiling ofl-isocorypalmine in rat urine, plasma, and feces after oral administration using high performance liquid chromatography coupled to Fourier transform ion cyclotron resonance mass spectrometry

Pharmacokinetic study of three different formulations of l-tetrahydropalmatine in brain tissues of rats

l-Tetrahydropalmatine (l-THP), an active alkaloid compound isolated from Rhizoma Corydalis-yanhusuo, has been reported to possess biological activity for treating cocaine use. To enhance both oral bioavailability and brain penetration, three formulations of l-THP suspension, mixture of l-THP-puerarin and self-microemulsifying drug delivery systems (SMEDDS) were prepared. A sensitive and reliable ultra-high-performance liquid chromatography with tandem mass spectrometry method was developed and validated for the simultaneous determination of l-THP and its active metabolite l-isocorypalmine (l-ICP) in rat brain. Diazepam was used as the internal standard. The chromatographic separation was achieved on a Bonshell ASB C₁₈ column at 30°C using acetonitrile-aqueous formic acid as mobile phase in gradient mode. The linearity was validated over the concentration ranges of 4.00-2,500 ng/ml for l-THP and 0.400-500 ng/ml for l-ICP. Full method validation was within the acceptance limits. The method was successfully used to determine the pharmacokinetics of two analytes following oral administration of these three formulations to rats. A significant difference was observed in the main pharmacokinetic parameters between SMEDDS and the suspension, and a 3.25- and 2.97-fold increase in the relative bioavailability of l-THP and l-ICP, respectively, was observed with the SMEDDS compared with the suspension formulation. It was concluded that SMEDDS enhanced the absorption of l-THP and l-ICP and delayed their release in brain.

Metabolic profiling of ligustilide and identification of the metabolite in rat and human hepatocytes by liquid chromatography combined with high-resolution mass spectrometry

Ligustilide is one of the most abundant bioactive ingredients in Rhizoma Chuanxiong that has been widely prescribed for medicinal purposes in China. To better understand the disposition and action of ligustilide, it is necessary to investigate the metabolic profiles. The in vitro metabolism was elucidated through incubating ligustilide with human and rat hepatocytes at 37°C. The incubation samples were collected at predefined time points to determine the metabolic stability. Upon metabolite identification and profiling, the incubation samples were analyzed by ultra-high-performance liquid chromatography combined with diode array detector and high-resolution mass spectrometry. The structures of the metabolites were characterized based on their mass spectrometry spectra, tandem mass spectrometry spectra, and fragmentation patterns. Ligustilide showed fast metabolism with high intrinsic clearance both in rat and human hepatocyte incubations. The half-lives of ligustilide in rat and human hepatocyte incubations were 8.0 and 15.0 min, respectively. Most of the parent (>90%) was biotransformed into the metabolites. Among these metabolites, M1 (senkyunolide I) was the major metabolite both in rat and human hepatocytes with the percentage of 42 and 70%, respectively. The metabolic pathways of ligustilide included epoxidation, epoxide hydrolysis, aromatization, hydroxylation, and glutathionylation. This work provided an overview of the metabolic profiles of ligustilide, which would be helpful for us to understand the action of this compound.

Tetrahydroprotoberberines: A Novel Source of Pharmacotherapies for Substance Use Disorders?

Tetrahydroprotoberberines (THPBs) are a class of compounds that target both dopamine D1 and D2 families of receptors, making them attractive candidates for treating substance use disorder (SUD). The binding of some THPBs to serotonin and adrenergic receptors, in addition to dopamine receptors, gives rise to complex pharmacological profiles. Significant progress has been made over the last decade in examining these compounds for their therapeutic potential. Here, we evaluate recent discoveries relating to the neural mechanism and therapeutic effects of THPBs, focusing on compounds that have shown promise in animal models of SUD and preliminary clinical studies. Advancements in structure-activity relationship studies and in silico modeling of THPB binding to dopamine receptors have facilitated the synthesis of novel THPBs with enhanced therapeutic properties and provide insights regarding use of the THPB scaffold to serve as a template for innovative drug designs.