Alfredo Capretta

Access to flavones via a microwave-assisted, one-pot Sonogashira-carbonylation-annulation reaction.

Palladium complexes of 1,3,5,7-tetramethyl-2,4,8-trioxa-6-phenyl-6-phosphaadamantane are shown to be effective catalytic systems facilitating the sequential application of a microwave-assisted Sonogashira and carbonylative annulation reaction for the preparation of substituted flavones.

Chemical Perturbation of Secondary Metabolism Demonstrates Important Links to Primary Metabolism

Bacterially produced secondary metabolites are used as antibiotics, anticancer drugs, and for many other medicinal applications. The mechanisms that limit the production of these molecules in the laboratory are not well understood, and this has impeded the discovery of many important compounds. We have identified small molecules that remodel the yields of secondary metabolites in many actinomycetes and show that one set of these molecules does so by inhibiting fatty acid biosynthesis. This demonstrates a particularly intimate relationship between this primary metabolic pathway and secondary metabolism and suggests an approach to enhance the yields of metabolites for discovery and biochemical characterization.

HDAC Inhibition Suppresses Primary Immune Responses, Enhances Secondary Immune Responses, and Abrogates Autoimmunity During Tumor Immunotherapy

Histone deacetylase inhibitors (HDACi) can modulate innate antiviral responses and render tumors more susceptible to oncolytic viruses (OVs); however, their effects on adaptive immunity in this context are largely unknown. Our present study reveals an unexpected property of the HDACi MS-275 that enhances viral vector-induced lymphopenia leading to selective depletion of bystander lymphocytes and regulatory T cells while allowing expansion of antigen-specific secondary responses. Coadministration of vaccine plus drug during the boosting phase focuses the immune response on the tumor by suppressing the primary immune response against the vaccine vector and enhancing the secondary response against the tumor antigen. Furthermore, improvement of T cell functionality was evident suggesting that MS-275 can orchestrate a complex array of effects that synergize immunotherapy and viral oncolysis. Surprisingly, while MS-275 dramatically enhanced efficacy, it suppressed autoimmune pathology, profoundly improving the therapeutic index.

Strategies and Synthetic Methods Directed Toward the Preparation of Libraries of Substituted Isoquinolines

Strategies for the production of substituted isoquinoline libraries were developed and explored. Routes involving microwave-assisted variants of the Bischler-Napieralski or Pictet-Spengler reaction allowed for cyclization of substituted beta-arylethylamine derivatives. The dihydroisoquinolines and tetrahydroisoquinolines thus generated could then be oxidized to their corresponding isoquinoline analogues. An alternate strategy, however, involving the preparation and activation of isoquinolin-1(2H)-ones is demonstrated to be a more practical, rapid, and efficient route to C1- and C4-substituted isoquinoline libraries.

Hexosamine biosynthesis pathway flux promotes endoplasmic reticulum stress, lipid accumulation, and inflammatory gene expression in hepatic cells

There is increasing evidence that endoplasmic reticulum (ER) stress contributes to the development of atherosclerosis in diabetes mellitus. The purpose of this study was to determine the effects of increased hexosamine biosynthesis pathway (HBP) flux on ER stress levels and the complications of ER stress associated with diabetes and atherosclerosis in hepatic cells. Glutamine:fructose-6-phosphate amidotransferase (GFAT), the rate-limiting enzyme of the HBP, was overexpressed in HepG2 cells by use of an adenoviral expression system. The ER stress response and downstream effects, including activation of lipid and inflammatory pathways, were determined using real-time PCR, immunoblot analysis, and cell staining techniques. GFAT overexpression resulted in increased expression of ER stress markers, including Grp78, Grp94, calreticulin, and GADD153, relative to cells infected with an empty adenoviral vector. In addition, GFAT overexpression promoted lipid, but not cholesterol, accumulation in hepatic cells as well as inflammatory pathway activation. Treatment with 6-diazo-5-oxo-norleucine, a GFAT antagonist, blocked the effects of GFAT overexpression. Consistent with our in vitro data, hyperglycemic mice presented with elevated markers of hepatic ER stress, glucosamine and lipid accumulation. Together, these data suggest that HBP flux-induced ER stress plays a role in the development of hepatic steatosis and atherosclerosis under conditions of hyperglycemia.

Intramolecular Carbenoid Insertions: the Reactions of α-Diazoketones Derived from Pyrrolyl and Indolyl Carboxylic Acids with Rhodium(II) Acetate

Abstract α-Diazoketones derived from pyrrolyl- and indolyl-carboxylic acids were prepared and their Rh 2 (OAc) 4 catalyzed decomposition chemistry was studied. These reactions generally resulted in the alkylation of the heteroaromatic system by the ketocarbenoid and in some instances the systems underwent CH or NH insertions. Evidence that some of these reactions proceed via a cyclopropane intermediate is presented. The methodology described provides facile access to fused pyrrolyl– or indolyl–cycloalkanone systems wherein the carbonyl is beta to the heteroaromatic system.

CORM-3-derived CO modulates polymorphonuclear leukocyte migration across the vascular endothelium by reducing levels of cell surface-bound elastase.

Recently, it has been shown that carbon monoxide (CO)-releasing molecule (CORM)-released CO can suppress inflammation. In this study, we assessed the effects and potential mechanisms of a ruthenium-based water-soluble CO carrier [tricarbonylchloroglycinate-ruthenium(II) (CORM-3)] in the modulation of polymorphonuclear leukocyte (PMN) inflammatory responses in an experimental model of sepsis. Sepsis in mice was induced by cecal ligation and puncture. CORM-3 (3 mg/kg iv) was administered 15 min after the induction of cecal ligation and puncture. PMN accumulation in the lung (myeloperoxidase assay), bronchoalveolar lavage (BAL) fluid, and lung vascular permeability (protein content in BAL fluid) were assessed 6 h later. In in vitro experiments, human PMNs were primed with LPS (10 ng/ml) and subsequently stimulated with formyl-methionyl-leucylphenylalanine (fMLP; 100 nM). PMN production of ROS (L-012/dihydrorhodamine-123 oxidation), degranulation (release of elastase), and PMN rolling, adhesion, and migration to/across human umbilical vein endothelial cells (HUVECs) were assessed in the presence or absence of CORM-3 (1-100 muM). The obtained results indicated that systemically administered CORM-3 attenuates PMN accumulation and vascular permeability in the septic lung. Surprisingly, in in vitro experiments, treatment of PMNs with CORM-3 further augmented LPS/fMLP-induced ROS production and the release of elastase. The latter effects, however, were accompanied by an inability of PMNs to mobilize elastase to the cell surface (plasma membrane), an event required for efficient PMN transendothelial migration. The CORM-3-induced decrease in cell surface levels of elastase was followed by decreased PMN rolling/adhesion to HUVECs and complete prevention of PMN migration across HUVECs. In contrast, treatment of HUVECs with CORM-3 had no effect on PMN transendothelial migration. Taken together, these findings indicate that, in sepsis, CORM3-released CO, while further amplifying ROS production and degranulation of PMNs, concurrently reduces the levels of cell surface-bound elastase, which contributes to suppressed PMN transendothelial migration.

Parallel synthesis of substituted imidazoles from 1,2-aminoalcohols

Substituted imidazoles can be prepared efficiently from cyclic or acyclic 1,2-aminoalcohols via a four-step procedure involving acylation of the amine, oxidation of the alcohol, imine formation and cyclization. Examples are presented and the methodology is applied in the generation of a library of compounds containing a fused imidazole-azepine motif.

Suzuki cross-coupling reactions of aryl halides in phosphonium salt ionic liquid under mild conditions

The Suzuki cross-coupling of aryl boronic acids with aryl halides, including aryl chlorides, proceeds in the phosphonium salt ionic liquid tetradecyltrihexylphosphonium chloride under mild conditions.

Novel chiral phosphines derived from limonene: the synthesis and structure of 4,8-dimethyl-2-phosphabicyclo[3.3.1]nonane

Abstract The radical addition of PH 3 to limonene results in the formation of 4,8-dimethyl-2-phosphabicyclo[3.3.1]nonane, which has been characterized by X-ray crystallographic analyses of its oxidation products, 2-(4-methylcyclohexyl)propylphosphonic acid and 4,8-dimethyl-2-phosphabicyclo[3.3.1]nonan-2-ol-oxide.