The Direct and Enantioselective Organocatalytic α-Oxidation of Aldehydes

The first direct enantioselective catalytic α-oxidation of carbonyls has been accomplished. The use of enamine catalysis has provided a new organocatalytic strategy for the enantioselective oxyamination of aldehydes, to generate α-oxyaldehydes, important chiral synthons for natural product and medicinal agent synthesis. The use of l-proline as the asymmetric catalyst has been found to mediate the oxidation of a large variety of aldehyde substrates with nitrosobenzene serving as the electrophilic oxidant. A diverse spectrum of aldehyde substrates can also be accommodated in this new organocatalytic transformation. While catalyst quantities of 2 mol % were generally employed in this study, successful oxidations conducted using catalyst loadings as low as 0.5 mol % are described

IN VITRO AND IN VIVO DISPOSITION OF 2,2-DIMETHYL-N-(2,4,6- TRIMETHOXYPHENYL)DODECANAMIDE (CI-976) Identification of a Novel Five-Carbon Cleavage Metabolite in Rats

ABSTRACT: The metabolism of CI-976, a potent inhibitor of liver and intestinal acyl coenzyme A:cholesterol acyltransferase, was investigated in isolated rat hepatocytes and Wistar rats after oral administration. The major metabolite observed both in vitro and in vivo was identified as the 6-carbon, chain-shortened 5,5-dimethyl-6-oxo-[(2,4,6-trimethoxyphenyl)amino]hexanoic acid (M-4). M-4 was determined to be formed from the -carboxylic acid 11,11-dimethyl-12-oxo ACAT 2 , (E.C. 2.3.1.1.26) is a key enzyme involved in cholesterol absorption from the gastrointestinal tract and cholesterol deposition in the body (1). The therapeutic potential of ACAT inhibitors as lipid lowering and antiatherosclerotic agents has been postulated for the treatment of hypercholesterolemia (2). The fatty acid anilide, CI-976 ( In vivo pharmacokinetic studies in male rats found CI-976 to have moderate absorption and bioavailability (29%), with an intravenous elimination half-life of 8 hr (6). After intravenous or oral administration to male rats, CI-976 was extensively metabolized to a single major urinary metabolite identified as M-4 ( To understand further the metabolism of CI-976, studies to determine the disposition and metabolism in rats were performed. The metabolism of CI-976 was examined both in hepatocyte suspensions and after oral administration to both male and female rats. In these studies, the metabolic pathways leading to the formation of M-4 were explored using metabolic intermediates as substrates, and by examining the effects of various inhibitors and inducers on the metabolism of CI-976 in hepatocyte incubations. Metabolites found in postreaction hepatocyte incubations and rat urine were characterized by HPLC, LC/MS, and GC/MS. Similar types of experiments were conducted with a new metabolite observed both in vitro and in vivo, which arises from an unusual mechanism (i.e. removal of 5-carbon units from the CI-976 fatty acid side chain). Materials and Methods CI-976 and [ 14 C]CI-976 (20.72 Ci/mg ring-labeled, 99.5% chemical and radiochemical purity); methyl-5,5-dimethyl-6-oxo-6-[(2,4,6-trimethoxyphe

Current Industrial Practices in Assessing CYP450 Enzyme Induction: Preclinical and Clinical

Induction of drug metabolizing enzymes, such as the cytochromes P450 (CYP) is known to cause drug-drug interactions due to increased elimination of co-administered drugs. This increased elimination may lead to significant reduction or complete loss of efficacy of the co-administered drug. Due to the significance of such drug interactions, many pharmaceutical companies employ screening and characterization models which predict CYP enzyme induction to avoid or attenuate the potential for drug interactions with new drug candidates. The most common mechanism of CYP induction is transcriptional gene activation. Activation is mediated by nuclear receptors, such as AhR, CAR, and PXR that function as transcription factors. Early high throughput screening models utilize these nuclear hormone receptors in ligand binding or cell-based transactivation/reporter assays. In addition, immortalized hepatocyte cell lines can be used to assess enzyme induction of specific drug metabolizing enzymes. Cultured primary human hepatocytes, the best established in vitro model for predicting enzyme induction and most accepted by regulatory agencies, is the predominant assay used to evaluate induction of a wide variety of drug metabolizing enzymes. These in vitro models are able to appropriately predict enzyme induction in patients when compared to clinical drug-drug interactions. Finally, transgenic animal models and the cynomolgus monkey have also been shown to recapitulate human enzyme induction and may be appropriate in vivo animal models for predicting human drug interactions

Neuronal Deletion of Caspase 8 Protects against Brain Injury in Mouse Models of Controlled Cortical Impact and Kainic Acid-Induced Excitotoxicity

system. mice demonstrated superior survival, reduced seizure severity, less apoptosis, and reduced caspase 3 processing. Uninjured aged knockout mice showed improved learning and memory, implicating a possible role for caspase 8 in cognitive decline with aging.Neuron-specific deletion of caspase 8 reduces brain damage and improves post-traumatic functional outcomes, suggesting an important role for this caspase in pathophysiology of acute brain trauma