Michele Luche

Synthesis and SAR of 4-aryl-1-(indazol-5-yl)pyridin-2(1H)ones as MCH-1 antagonists for the treatment of obesity.

A new series of 4-aryl-1-(indazol-5-yl)pyridin-2(1H)ones possessing MCH-1 receptor antagonism is presented. Suzuki coupling of boronic acids with key triflate 6 allowed rapid generation of a range of analogs. The SAR of the MCH-1 receptor was explored with a variety of aryl and heterocyclic moieties. Selected compounds were studied in a five-day diet induced obese mouse model to evaluate their potential use as weight loss agents.

Tetrahydrocarboline analogs as MCH-1 antagonists

A new series of tetrahydrocarbolines with potent MCH-1 antagonist activity were synthesized, using a conformationally constrained design approach towards optimizing pharmacokinetic properties. Two compounds from this series were progressed to a 5-day diet-induced obesity mouse screening model to evaluate their potential as weight loss agents. Both compounds produced a highly significant reduction in weight, which was attributed to their improved pharmacokinetic profile.

Citreamicins with potent gram-positive activity.

Two new xanthone antibiotics, citreamicin delta (1) and epsilon (2), with potent activity against Gram-positive pathogens including multidrug-resistant Staphylococcus aureus (MDRSA) were discovered. Compounds 1 and 2 exhibited MIC values < 1 microg/mL versus a number of resistant strains. The compounds were obtained from EtOAc extracts of Streptomyces vinaceus and were purified by countercurrent chromatography and reversed-phase HPLC. Their structures were elucidated using primarily NMR and mass spectroscopy.

Leporizines A–C: Epithiodiketopiperazines Isolated from an Aspergillus Species

Three new compounds named leporizines A-C have been isolated from an Aspergillus sp. strain. Their structures were elucidated by analysis of 1D and 2D NMR spectra. Leporizines A and B were isolated during dereplication of hits from a high-throughput screening campaign for correctors of the cystic fibrosis transmembrane conductance regulator (CFTR), and leporizine C was isolated while preparing additional material for characterization of leporizines A and B. CFTR activity observed for leporizines A and B was highly correlated with cell toxicity and was determined to be a nonspecific effect. Leporizine C was not cytotoxic to cells and did not elicit a response in the CFTR assays. To the best of our knowledge, leporizines A-C represent the first examples of this unusual epithiodiketopiperazine skeleton.

Design, synthesis, and SAR of N-((1-(4-(propylsulfonyl)piperazin-1-yl)cycloalkyl)methyl)benzamide inhibitors of glycine transporter-1

The design, synthesis, and structure-activity relationships (SAR) of a series of N-((1-(4-(propylsulfonyl)piperazin-1-yl)cycloalkyl)methyl)benzamide inhibitors of glycine transporter-1 (GlyT-1) are described. Optimization of the benzamide and central ring components of the core scaffold led to the identification of a GlyT-1 inhibitor that demonstrated in vivo activity in a rodent cerebral spinal fluid (CSF) glycine model.

Neopyrrolomycins with broad spectrum antibacterial activity.

Three new antibiotics, neopyrrolomycins B (1), C (2), and D (3), with potent activity against Gram-positive pathogens were discovered. They exhibited MIC values < 1 microg/mL versus a number of resistant strains. The compounds were obtained from the ethyl acetate extracts of a Streptomyces sp. after purification by column chromatography and RP-HPLC. Their structures were elucidated using X-ray crystallography (1) and NMR spectroscopy (2 and 3).

Mutactimycin E, a New Anthracycline Antibiotic with Gram-positive Activity

Resistance to currently available antibiotics has become a widely recognized crisis in the medical community. To address this, many companies and researchers are refocusing their attention towards natural products, which have an excellent track record of producing effective antibacterial drugs. The AMRI natural product library was screened for activity against multi-drug resistant Staphylococcus aureus (MDRSA). The active samples were counter screened for cytotoxicity against the human hepatocellular carcinoma HepG2 cell line to determine an in vitro therapeutic index (in vitro TI). Those samples with a high in vitro TI were selected for fractionation and dereplication. This led to the discovery of a new anthracycline structure. This metabolite, named mutactimycin E (1), exhibited moderate activity against several gram positive organisms. Here we report the isolation, structure elucidation and biological activities of this new compound.

Synthesis and Biological Evaluation of N-((1-(4-(Sulfonyl)piperazin-1-yl)cycloalkyl)methyl)benzamide Inhibitors of Glycine Transporter-1.

We previously disclosed the discovery of rationally designed N-((1-(4-(propylsulfonyl)piperazin-1-yl)cycloalkyl)methyl)benzamide inhibitors of glycine transporter-1 (GlyT-1), represented by analogues 10 and 11. We describe herein further structure-activity relationship exploration of this series via an optimization strategy that primarily focused on the sulfonamide and benzamide appendages of the scaffold. These efforts led to the identification of advanced leads possessing a desirable balance of excellent in vitro GlyT-1 potency and selectivity, favorable ADME and in vitro pharmacological profiles, and suitable pharmacokinetic and safety characteristics. Representative analogue (+)-67 exhibited robust in vivo activity in the cerebral spinal fluid glycine biomarker model in both rodents and nonhuman primates. Furthermore, rodent microdialysis experiments also demonstrated that oral administration of (+)-67 significantly elevated extracellular glycine levels within the medial prefrontal cortex (mPFC).

5-Hydroxy ericamycin, a new anthraquinone with potent antimicrobial activity

The departure of many pharmaceutical companies from antibiotic research starting in the 1980s resulted in the absence of new antibiotics to combat the current crisis of increasing microbial resistance to currently available antibiotics. In an effort to address the increasing need for novel antibiotics, AMRI began a screening campaign to identify potent compounds from our natural product library. Natural products, particularly those produced by microbial fermentation, were the direct source or inspiration for almost all antibiotics used today and remain the richest source for new antibacterial compound series. AMRI’s extensive library consisting of over 280 000 samples was screened for activity against a multi-drug resistant strain of Staphylococcus aureus (ATCC 43 300, Rockville, MD, USA). The hits arising out of this assay were then tested against the human hepatocellular carcinoma cell line HepG2 to filter out those samples where activity was the result of general cytotoxicity and determine an in vitro therapeutic index (in vitro TI). Samples with a high in vitro TI were selected for fractionation and dereplication. The resulting subset of samples possessing selectivity for the bacterial target were then fractionated on an HPLC system employing UV, ELSD (evaporative light scattering) and MS detectors. The eluted fractions were collected into 96-well microtiter plates and submitted for bioassay. LC/MS data for the active fractions generated UV spectra and molecular weights, which were used to search internal and external databases.1 The analysis of the extract from strain 4731, which exhibited excellent activity against several Gram-positive organisms, resulted in the discovery of a new anthraquinone, which was closely related to the known antibiotic ericamycin.2,3 Here we report the isolation, structure elucidation and biological activities of 1. The Actinoplanes sp. strain 4731 was isolated from a soil sample collected from grassland near Nanton, in Alberta, Canada. The culture was isolated by a previously described capillary chemotaxis technique,4 using 0.18% mannitol as a chemo-attractant, spread-plating on water-yeast extract agar plates5 and incubating in the dark at 28 1C for 10 days. All colonies visible under a dissecting scope were transferred to and purified on starch casein agar plates. Pure cultures were macerated and stored in a 10% glycerol/5% lactose solution at 80 1C. Before fermentation, the culture was streaked from a cryovial onto starch casein agar to verify purity. Fresh culture macerate was prepared from these agar plates after 14 days and used to inoculate the fermentation. Strain 4731 was identified by sequencing of the 16S rRNA gene. Genomic DNA was isolated from a culture grown in tryptic soy broth for 7 days at 28 1C by a phenol:chloroform extraction method.6 The 16S rRNA gene was amplified using Taq polymerase (Promega, Madison, WI, USA) and the following two primer pairs: 27F, 50-AGA GTTTGATCMTGGCTCAG-30; 1115R, 50-AGGGTTGCGCTCGTTG-30; and 339F, 50-CTCCTACGGGAGGCAGCAG-30; 1429R, 50-TACGGYT ACCTTGTTACGACTT-30. An NCBI BLAST search of our consensus sequence showed the four closest matches (99% max identity) were all Actinoplanes strains. The fermentation procedure utilized was a two-step process, in which a suspension of culture macerate (mycelium and spores) was inoculated into 250-ml flasks containing 30 ml of a nutrient seed medium having the following composition per liter: 20 g D-glucose, 15 g Pharmamedia (ADM Traders Protein, Lubbock, TX, USA), 5 g yeast extract (Difco, Franklin Lakes, NJ, USA), 4 g CaCO3, 3 g (NH4)2SO4 and 0.03 g ZnSO4 7 H2O, adjusted to pH 6.5 before autoclaving. After inoculation, the flasks were incubated on a rotary shaker at 250 r.p.m. (20 0 throw) and 28 1C for 2 days. One milliliter aliquots of the seed culture were then used to inoculate one hundred 250-ml flasks containing 30 ml of a production medium with the following composition per liter: 30 g D-glucose, 10 g maltose, 20 g Quaker oatmeal and 4 g yeast extract, adjusted to pH 7.0 before autoclaving. Following inoculation, the production flasks were incubated on a rotary shaker at 250 r.p.m. and 28 1C for 8 days. The combined cultures (B3 l) were harvested by extracting with an equal volume of ethyl acetate resulting in a total extract volume