APPLICATION OF BIOCATALYSIS TO DRUG METABOLISM: PREPARATION OF MAMMALIAN METABOLITES OF A BIARYL-BIS-SULFONAMIDE AMPA (α-AMINO-3-HYDROXY-5-METHYLISOXAZOLE-4-PROPIONIC ACID) RECEPTOR POTENTIATOR USING Actinoplanes missouriensis

AMPA receptor potentiators: from drug design to cognitive enhancement

Positive allosteric modulators of ionotropic glutamate receptors have emerged as a target for treating cognitive impairment and neurodegeneration, but also mental illnesses such as major depressive disorder. The possibility of creating a new class of pharmaceutical agent to treat refractive mental health issues has compelled researchers to redouble their efforts to develop a safe, effective treatment for memory and cognition impairments. Coupled with the more robust research methodologies that have emerged, including more sophisticated high-throughput-screens, higher resolution structural biology techniques, and more focused assessment on pharmacokinetics, the development of positive modulators of AMPA receptors holds great promise. We describe recent approaches that improve our understanding of the basic physiology underlying memory and cognition, and their application toward promoting human health.

Twenty-six years of HIV science: an overview of anti-HIV drugs metabolism

From the identification of HIV as the agent causing AIDS, to the development of effective antiretroviral drugs, the scientific achievements in HIV research over the past twenty-six years have been formidable. Currently, there are twenty-five anti-HIV compounds which have been formally approved for clinical use in the treatment of AIDS. These compounds fall into six categories: nucleoside reverse transcriptase inhibitors (NRTIs), nucleotide reverse transcriptase inhibitors (NtRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs), protease inhibitors (PIs), cell entry inhibitors or fusion inhibitors (FIs), co-receptor inhibitors (CRIs), and integrase inhibitors (INIs). Metabolism by the host organism is one of the most important determinants of the pharmacokinetic profile of a drug. Formation of active or toxic metabolites will also have an impact on the pharmacological and toxicological outcomes. Therefore, it is widely recognized that metabolism studies of a new chemical entity need to be addressed early in the drug discovery process. This paper describes an overview of the metabolism of currently available anti-HIV drugs.

Production of human phase 1 and 2 metabolites by whole-cell biotransformation with recombinant microbes

Cytochrome P450 enzymes (CYPs or P450s) are the most important enzymes involved in the phase I metabolism of drugs and poisons in humans, while UDP glycosyltransferases catalyze the majority of phase II reactions. In addition, a number of other enzymes or enzyme families contribute to the metabolism of xenobiotica, including alcohol dehydrogenase, aldehyde dehydrogenase, ester and amide hydrolases, epoxide hydrolase and flavine monooxygenases, as well as sulfotransferases, catechol-O-methyltransferase and N-acetyltransferase. A thorough understanding of their activity and of the properties of the metabolites they form is an essential prerequisite for the assessment of drug-caused side effects or toxicity. In this context of MIST, efficient production systems are needed to permit the large-scale production of human drug metabolites. As classical chemical synthesis cannot always provide these metabolites, biotechnological approaches have been developed that typically employ the recombinant expression of human drug-metabolizing enzymes. This review summarizes the current knowledge regarding whole-cell biotransformation processes that make use of such an approach.

Determination and identification of estrogenic compounds generated with biosynthetic enzymes using hyphenated screening assays, high resolution mass spectrometry and off-line NMR

This paper describes the determination and identification of active and inactive estrogenic compounds produced by biosynthetic methods. A hyphenated screening assay towards the human estrogen receptor ligand binding domain (hER)alpha and hERbeta integrating target-ligand interactions and liquid chromatography-high resolution mass spectrometry was used. With this approach, information on both biologic activity and structure identity of compounds produced by bacterial mutants of cytochrome P450s was obtained in parallel. Initial structure identification was achieved by high resolution MS/MS, while for full structure determination, P450 incubations were scaled up and the produced entities were purified using preparative liquid chromatography with automated fraction collection. NMR spectroscopy was performed on all fractions for 3D structure analysis; this included 1D-(1)H, 2D-COSY, 2D-NOESY, and (1)H-(13)C-HSQC experiments. This multidimensional screening approach enabled the detection of low abundant biotransformation products which were not suitable for detection in either one of its single components. In total, the analytical scale biosynthesis produced over 85 compounds from 6 different starting templates. Inter- and intra-day variation of the biochemical signals in the dual receptor affinity detection system was less than 5%. The multi-target screening approach combined with full structure characterization based on high resolution MS(/MS) and NMR spectroscopy demonstrated in this paper can generally be applied to e.g. metabolism studies and compound-library screening.

Identification and characterization of a bacterial cytochrome P450 for the metabolism of diclofenac

The bacterium Actinoplanes sp. ATCC 53771 is known to perform drug metabolism of several xenobiotics similarly to humans. We identified a cytochrome P450 enzyme from this strain, CYP107E4, and expressed it in Escherichia coli using the pET101 vector. The purified enzyme showed the characteristic reduced-CO difference spectra with a peak at 450 nm, indicating the protein is produced in the active form with proper heme incorporation. The CYP107E4 enzyme was found to bind the drug diclofenac. Using redox enzymes from spinach, the reconstituted system is able to produce hydroxylated metabolites of diclofenac. Production of the human 4'-hydroxydiclofenac metabolite by CYP107E4 was confirmed, and a second hydroxylated metabolite was also produced.