Biotechnology Based Process for Production of a Disulfide-Bridged Peptide.

A disulfide-bridged peptide drug development candidate contained two oligopeptide chains with 11 and 12 natural amino acids joined by a disulfide bond at the N-terminal end. An efficient biotechnology based process for the production of the disulfide-bridged peptide was developed. Initially, the two individual oligopeptide chains were prepared separately by designing different fusion proteins and expressing them in recombinant E. coli. Enzymatic or chemical cleavage of the two fusion proteins provided the two individual oligopeptide chains which could be conjugated via disulfide bond by conventional chemical reaction to the disulfide-bridged peptide. A novel heterodimeric system to bring the two oligopeptide chains closer and induce disulfide bond formation was designed by taking advantage of the self-assembly of a leucine zipper system. The heterodimeric approach involved designing fusion proteins with the acidic and basic components of the leucine zipper, additional amino acids to optimize interaction between the individual chains, specific cleavage sites, specific tag to ensure separation, and two individual oligopeptide chains. Computer modeling was used to identify the nature and number of amino acid residue to be inserted between the leucine zipper and oligopeptides for optimum interaction. Cloning and expression in rec E. coli, fermentation, followed by cell disruption resulted in the formation of heterodimeric protein with the interchain disulfide bond. Separation of the desired heterodimeric protein, followed by specific cleavage at methionine by cyanogen bromide provided the disulfide-bridged peptide.

Microbial N-demethylation: biotransformation and recovery of a drug metabolite.

A total of 39 microbes were screened for the ability to selectively N-demethylate (3R,5S,E)-7-(4-(4-fluorophenyl)-6-isopropyl-2-(methyl(1-methyl-1H-1,2,4-triazol-5-yl)aminopyrimidin-5-yl)-3,5-dihydroxy-hept-6-enoic acid (I), a potential drug for lowering blood cholesterol levels. Two Streptomyces species were found to carry out the desired N-demethylation. Bioconversion by Streptomyces griseus A.T.C.C. 13273 and product recovery were scaled up to the multi-gram level.

Discovery of Clinical Candidate 2-((2S,6S)-2-Phenyl-6-hydroxyadamantan-2-yl)-1-(3'-hydroxyazetidin-1-yl)ethanone [BMS-816336], an Orally Active Novel Selective 11ß-Hydroxysteroid Dehydrogenase Type 1 Inhibitor.

BMS-816336 (6n-2), a hydroxy-substituted adamantyl acetamide, has been identified as a novel, potent inhibitor against human 11ß-hydroxysteroid dehydrogenase type 1 (11ß-HSD1) enzyme (IC50 3.0 nM) with >10000-fold selectivity over human 11ß-hydroxysteroid dehydrogenase type 2 (11ß-HSD2). 6n-2 exhibits a robust acute pharmacodynamic effect in cynomolgus monkeys (ED50 0.12 mg/kg) and in DIO mice. It is orally bioavailable (%F ranges from 20 to 72% in preclinical species) and has a predicted pharmacokinetic profile of a high peak to trough ratio and short half-life in humans. This ADME profile met our selection criteria for once daily administration, targeting robust inhibition of 11ß-HSD1 enzyme for the first 12 h period after dosing followed by an "inhibition holiday" so that the potential for hypothalamic-pituitary-adrenal (HPA) axis activation might be mitigated. 6n-2 was found to be well-tolerated in phase 1 clinical studies and represents a potential new treatment for type 2 diabetes, metabolic syndrome, and other human diseases modulated by glucocorticoid control.

Efficient and scalable enantioselective synthesis of a CGRP antagonist.

An enantioselective synthesis of the CGRP antagonist BMS-846372, amenable to large scale preparation, is presented. This new synthesis showcases a chemo- and enantioselective reduction of a cyclohepta[b]pyridine-5,9-dione as well as a Pd-catalyzed alpha-arylation reaction to form the key carbon-carbon bond and set the absolute and relative stereochemistry.

Enzymatic C-4 deacetylation of 10-deacetylbaccatin III.

Second-generation paclitaxel analogues that require replacement of the C-4 acetate by other substituents are in development. An enzyme able to specifically remove the C-4 acetate from paclitaxel could simplify preparation of the analogues. Several strains were isolated from soil samples that contain enzyme activities able to 4-deacetylate 10-DAB (10-deacetylbaccatin III). Selection was made using plates containing 10-DAB as the sole carbon source and screening colonies for deacetylation of 10-DAB. Two strains initially isolated were identified as Rhodococcus sp. and deposited with the A.T.C.C. (Manassas, VA, U.S.A.) as strains 202191 and 202192. Whole cells were able to convert 10-DAB into 4,10-DDAB (4-deacetyl-10-deacetylbaccatin III) in 90% yield. The enzyme activity in these strains was not effective with paclitaxel and 10-deacetylpaclitaxel, although 4,10-DDAB was produced from baccatin III. The activity in these strains was associated with an insoluble fraction of cell extracts. Several additional isolates were obtained that were identified as variants of Stenotrophomonas maltophilia, and a soluble C-4 deacetylase was purified approx. 218-fold from one of them. The activity of this enzyme was limited to 10-DAB, and the enzyme was not effective with paclitaxel or baccatin III.

Conversion of 7-deoxy-10-deacetylbaccatin-III into 6-alpha-hydroxy-7-deoxy-10-deacetylbaccatin-III by Nocardioides luteus.

6-alpha-Hydroxy-7-deoxy-10-deacetylbaccatin-III is an intermediate that is potentially useful for synthesis of analogues of paclitaxel. Screening of microbial strains identified an enzyme activity in Nocardioides luteus SC 13912 (A.T.C.C. 55426) which converted 7-deoxy-10-deacetylbaccatin-III into 6-hydroxy-7-deoxy-10-deacetylbaccatin-III with a maximum yield of 44%.

Synthesis and activity of a C-8 keto pleuromutilin derivative.

A C-8 keto pleuromutilin derivative has been synthesized from the biotransformation product 8-hydroxy mutilin. A key step in the process was the selective oxidation at C-8 of 8-hydroxy mutilin using tetrapropylammonium perruthenate. The presence of the C-8 keto group precipitated interesting intramolecular chemistry to afford a compound (10) with a novel pleuromutilin-derived ring system.