RESUMEN
We developed a practical synthetic method for fluorine-18 (18F)-labeled pitavastatin ([18F]PTV) as a positron emission tomography (PET) tracer to assess hepatobiliary transporter activity and conducted a PET scan as a preclinical study for proof-of-concept in rats. This method is a one-pot synthesis involving aromatic 18F-fluorination of an arylboronic acid ester followed by deprotection under acidic conditions, which can be reproduced in general clinical sites equipped with a standard radiolabeling system due to the simplified procedure. PET imaging confirmed that intravenously administered [18F]PTV was rapidly accumulated in the liver and gradually transferred into the intestinal lumen through the bile duct. Radiometabolite analysis showed that [18F]PTV was metabolically stable, and 80% of the injected dose was detected as the unchanged form in both blood and bile. We applied integration plot analysis to assess tissue uptake clearance (CLuptake, liver and CLuptake, kidney) and canalicular efflux clearance (CLint, bile), and examined the effects of inhibitors on membrane transport. Treatment with rifampicin, an organic anion transporting polypeptide inhibitor, significantly reduced CLuptake, liver and CLuptake, kidney to 44% and 64% of control, respectively. In contrast, Ko143, a breast cancer resistance protein inhibitor, did not affect CLuptake, liver but significantly reduced CLint, bile to 39% of control without change in [18F]PTV blood concentration. In addition, we found decreased CLuptake, liver and increased CLint, bile in Eisai hyperbilirubinemic rats in response to altered expression levels of transporters. We expect that [18F]PTV can be translated into clinical application, as our synthetic method does not need special apparatus in the radiolabeling system and PET scan with [18F]PTV can quantitatively evaluate transporter activity in vivo.
Asunto(s)
Radioisótopos de Flúor/química , Quinolinas/química , Transportador de Casetes de Unión a ATP, Subfamilia G, Miembro 2/efectos de los fármacos , Transportador de Casetes de Unión a ATP, Subfamilia G, Miembro 2/metabolismo , Animales , Western Blotting , Cromatografía en Capa Delgada , Hígado/efectos de los fármacos , Hígado/metabolismo , Masculino , Estructura Molecular , Proteínas de Neoplasias/efectos de los fármacos , Proteínas de Neoplasias/metabolismo , Transportadores de Anión Orgánico/efectos de los fármacos , Transportadores de Anión Orgánico/metabolismo , Tomografía de Emisión de Positrones , Ratas , Ratas Sprague-Dawley , Rifampin/químicaRESUMEN
Transformation of aromatic thioesters into arylboronic esters was achieved efficiently using a rhodium catalyst. The broad functional-group tolerance and mild conditions of the method have allowed for the two-step decarboxylative borylation of a wide range of aromatic carboxylic acids, including commercially available drugs.
RESUMEN
Ni/Cu-catalyzed transformation of fluoroarenes to arylboronic acid pinacol esters via C-F bond cleavage has been achieved. Further versatile derivatization of an arylboronic ester has allowed for the facile two-step conversion of a fluoroarene to diverse functionalized arenes, demonstrating the synthetic utility of the method.
RESUMEN
It is widely accepted that uptake and efflux transporters on clearance organs play crucial roles in drug disposition. Although in vitro transporter assay system can identify the intrinsic properties of the target transporters, it is not so easy to precisely predict in vivo pharmacokinetic parameters from in vitro data. Positron emission tomography (PET) imaging is a useful tool to directly assess the activity of drug transporters in humans. We recently developed a practical synthetic method for fluorine-18-labeled pitavastatin ([18F]PTV) as a PET probe for quantitative evaluation of hepatobiliary transport. In the present study, we conducted clinical PET imaging with [18F]PTV and compared the pharmacokinetic properties of the probe for healthy subjects with or without rifampicin pretreatment. Rifampicin pretreatment significantly suppressed the hepatic maximum concentration and biliary excretion of the probe to 52% and 34% of the control values, respectively. Rifampicin treatment markedly decreased hepatic uptake clearance (21% of the control), and moderately canalicular efflux clearance with regard to hepatic concentration (52% of the control). These results demonstrate that [18F]PTV is a useful probe for clinical investigation of the activities of hepatobiliary uptake/efflux transporters in humans.
Asunto(s)
Quinolinas , Rifampin , Transporte Biológico , Humanos , Hígado/metabolismo , Proteínas de Transporte de Membrana/metabolismo , Quinolinas/metabolismo , Quinolinas/farmacología , Rifampin/metabolismo , Rifampin/farmacologíaRESUMEN
An efficient nickel catalyst system for the carboxylation of organozinc reagents with CO(2) under very mild conditions has been developed. The catalyst system complements the conventional methods and enables the direct synthesis of various saturated carboxylic acid derivatives from the corresponding alkylzinc reagents and CO(2).
RESUMEN
A convenient method for the stereoinversion of secondary alcohols, applicable to stereocongested carbocyclic substrates, is reported. A simple three-step procedure, including triflylation of the hydroxy group, nucleophilic oxygenative displacement by the treatment with aqueous N,N-dimethylformamide (DMF), and methanolysis, allowed for efficient stereoinversion of various substrates, including sugar derivatives, in one pot.