Total synthesis of (±)-cycloclavine and (±)-5-epi-cycloclavine.

Novel routes to the naturally occurring indole alkaloid cycloclavine and its unnatural C(5)-epimer are described. Key features include the rapid construction of the heterocyclic core segments by two Diels-Alder reactions. An indole annulation was accomplished by a late-stage intramolecular Diels-Alder furan cycloaddition, and a methylenecyclopropane dienophile was used for a stereoselective intramolecular [4 + 2] cycloaddition to give the cyclopropa[c]indoline building block present in cycloclavine.

Total synthesis of (-)-sessilifoliamide C and (-)-8-epi-stemoamide.

A convergent route featuring [3,3]-sigmatropic rearrangements of a linchpin azepinopyrrolidine served to install two of the four contiguous stereocenters present in the tricyclic Stemona alkaloids sessilifoliamide and stemoamide. In addition to the first total synthesis of (-)-sessilifoliamide C, a potential biosynthetic relationship between the sessilifoliamides and previously reported Stemona alkaloids is presented.

Chemical methodology as a source of small-molecule checkpoint inhibitors and heat shock protein 70 (Hsp70) modulators.

Unique chemical methodology enables the synthesis of innovative and diverse scaffolds and chemotypes and allows access to previously unexplored "chemical space." Compound collections based on such new synthetic methods can provide small-molecule probes of proteins and/or pathways whose functions are not fully understood. We describe the identification, characterization, and evolution of two such probes.

Two strategies for the development of mitochondrion-targeted small molecule radiation damage mitigators.

Purpose: To evaluate the effectiveness of mitigation of acute ionizing radiation damage by mitochondrion-targeted small molecules.

Methods And Materials: We evaluated the ability of nitroxide-linked alkene peptide isostere JP4-039, the nitric oxide synthase inhibitor-linked alkene peptide esostere MCF201-89, and the p53/mdm2/mdm4 protein complex inhibitor BEB55 to mitigate radiation effects by clonogenic survival curves with the murine hematopoietic progenitor cell line 32D cl 3 and the human bone marrow stromal (KM101) and pulmonary epithelial (IB3) cell lines. The p53-dependent mechanism of action was tested with p53(+/+) and p53(-/-) murine bone marrow stromal cell lines.

Large-scale asymmetric synthesis of the bioprotective agent JP4-039 and analogs.

JP4-039 is a novel nitroxide conjugate capable of crossing lipid bilayer membranes and scavenging reactive oxygen species (ROS). An efficient and scalable one-pot hydrozirconation-transmetalation-imine addition methodology has been developed for its asymmetric preparation. Furthermore, this versatile methodology allows for the synthesis of cyclopropyl and fluorinated analogs of the parent lead structure.

Residue preference mapping of ligand fragments in the Protein Data Bank.

The interaction between small molecules and proteins is one of the major concerns for structure-based drug design because the principles of protein-ligand interactions and molecular recognition are not thoroughly understood. Fortunately, the analysis of protein-ligand complexes in the Protein Data Bank (PDB) enables unprecedented possibilities for new insights. Herein, we applied molecule-fragmentation algorithms to split the ligands extracted from PDB crystal structures into small fragments.

Terminal alkene formation by the thioesterase of curacin A biosynthesis: structure of a decarboxylating thioesterase.

Curacin A is a polyketide synthase (PKS)-non-ribosomal peptide synthetase-derived natural product with potent anticancer properties generated by the marine cyanobacterium Lyngbya majuscula. Type I modular PKS assembly lines typically employ a thioesterase (TE) domain to off-load carboxylic acid or macrolactone products from an adjacent acyl carrier protein (ACP) domain. In a striking departure from this scheme the curacin A PKS employs tandem sulfotransferase and TE domains to form a terminal alkene moiety.

Synthesis of 2-hydrazolyl-4-thiazolidinones based on multicomponent reactions and biological evaluation against Trypanosoma Cruzi.

A series of 18 novel 2-hydrazolyl-4-thiazolidinones-5-carboxylic acids, amides and 5,6-α,β-unsaturated esters were synthesized, and their in vitro activity on cruzipain and T. cruzi epimastigotes was determined. Some agents show activity at 37 μm concentration in the enzyme assay.

Strategies for discovery of small molecule radiation protectors and radiation mitigators.

Mitochondrial targeted radiation damage protectors (delivered prior to irradiation) and mitigators (delivered after irradiation, but before the appearance of symptoms associated with radiation syndrome) have been a recent focus in drug discovery for (1) normal tissue radiation protection during fractionated radiotherapy, and (2) radiation terrorism counter measures. Several categories of such molecules have been discovered: nitroxide-linked hybrid molecules, including GS-nitroxide, GS-nitric oxide synthase inhibitors, p53/mdm2/mdm4 inhibitors, and pharmaceutical agents including inhibitors of the phosphoinositide-3-kinase pathway and the anti-seizure medicine, carbamazepine. Evaluation of potential new radiation dose modifying molecules to protect normal tissue includes: clonogenic radiation survival curves, assays for apoptosis and DNA repair, and irradiation-induced depletion of antioxidant stores.

Plasmodium falciparum encodes a single cytosolic type I Hsp40 that functionally interacts with Hsp70 and is upregulated by heat shock.

Heat shock protein 70 (Hsp70) and heat shock protein 40 (Hsp40) function as molecular chaperones during the folding and trafficking of proteins within most cell types. However, the Hsp70-Hsp40 chaperone partnerships within the malaria parasite, Plasmodium falciparum, have not been elucidated. Only one of the 43 P.

Intraesophageal administration of GS-nitroxide (JP4-039) protects against ionizing irradiation-induced esophagitis.

Background/aim: this study evaluated esophageal radioprotection by the Gramicidin S (GS) derived-nitroxide, JP4-039, a mitochondrial targeting peptide-isostere covalently-linked to 4-amino-Tempo, delivered in a novel swallowed oil-based (F15) formulation.

Materials And Methods: C57BL/6HNsd female mice received intraesophageal F15 formulation containing JP4-039 (4 mg/ml in 100 microl volumes) 10 minutes before 28 or 29 Gy upper body irradiation compared to MnSOD-PL (100 microl containing 100 microg plasmid) 24 hours prior to irradiation. Subgroups received 1 × 10(7) C57BL/6HNsd, GFP(+) male bone marrow cells intravenously 5 days after irradiation.

Regioselective Palladium-Catalyzed Cross-Coupling Reactions of 2,4,7-Trichloroquinazoline.

The regioselective palladium-catalyzed cross-coupling reactions of 2,4,7-trichloroquinazoline with various aryl- and heteroarylboronic acids are reported. An efficient, sequential strategy was developed that provides access to novel, functionalized heterocycles.

Pharmacophore Refinement Guides the Rational Design of Nanomolar-Range Inhibitors of the Botulinum Neurotoxin Serotype A Metalloprotease.

Botulinum neurotoxins (BoNTs) are the deadliest of microbial toxins. The enzymes' Zinc(II) metalloprotease, referred to as the light chain (LC) component, inhibits acetylcholine release into neuromuscular junctions, resulting in the disease botulism. Currently, no therapies counter BoNT poisoning post-neuronal intoxication; however, it is hypothesized that small molecules may be used to inhibit BoNT LC activity in the neuronal cytosol.

General solution to the synthesis of N-2-substituted 1,2,3-triazoles.

The regioselective N-alkylation of 1,2,3-triazoles 1-6 was studied. Good to excellent N-2 selectivity and high chemical yields for N-2-substituted 4,5-dibromotriazoles 7 were obtained with 4,5-dibromo- and 4-bromo-5-trimethylsilyl-1,2,3-triazoles. These building blocks can be readily converted to 2-mono-, 2,4-di-, and 2,4,5-polysubstituted triazoles 10-15, providing a general, protective, group-free method for the synthesis of N-2-substituted triazoles.

Synthesis and chemical diversity analysis of bicyclo[3.3.1]non-3-en-2-ones.

Functionalized bicyclo[3.3.1]non-3-en-2-ones are obtained from commercially available phenols by a hypervalent iodine oxidation, enone epoxidation, epoxide thiolysis, and intramolecular aldol reaction sequence.

Peptide-Like Molecules (PLMs): A Journey from Peptide Bond Isosteres to Gramicidin S Mimetics and Mitochondrial Targeting Agents.

Peptides are natural ligands and substrates for receptors and enzymes and exhibit broad physiological effects. However, their use as therapeutic agents often suffers from poor bioavailability and insufficient membrane permeability. The success of peptide mimicry hinges on the ability of bioisosteres, in particular peptide bond replacements, to adopt suitable secondary structures relevant to peptide strands and position functional groups in equivalent space.

Small molecule GS-nitroxide ameliorates ionizing irradiation-induced delay in bone wound healing in a novel murine model.

We studied radioprotection and mitigation by mitochondrial-targeted Tempol (GS-nitroxide, JP4-039), in a mouse injury/irradiation model of combined injury (fracture/irradiation). Right hind legs of control C57BL/6NHsd female mice, mice pretreated with MnSOD-PL, JP4-039, or with amifostine were irradiated with single and fractionated doses of 0 to 20 Gy. Twenty-four hours later, unicortical holes were drilled into the tibiae of both hind legs; at intervals, tibias were excised, radiographed, and processed for histology.

Studies toward a library of tetrahydrofurans: click and MCR products of mono- and bis-tetrahydrofurans.

Mono- and bis-tetrahydrofuran-based chemical libraries with diverse structural features have been prepared using the Sharpless azide-alkyne Click reaction and multi-component reactions (MCRs) such as Ugi and Biginelli reactions. Mono- and bis-tetrahydrofuran methyl azides, amines and ureas were key intermediates in these processes, and they were synthesized from the corresponding tetrahydrofuran methyl alcohols by mesylation followed by substitution with azide, reduction of the azide to the amine, and urea formation, as needed. Most mono- and tetrahydrofuran methyl alcohols were obtained by a Sharpless asymmetric dihydroxylation reaction.

Iterative structure-based peptide-like inhibitor design against the botulinum neurotoxin serotype A.

The botulinum neurotoxin serotype A light chain (BoNT/A LC) protease is the catalytic component responsible for the neuroparalysis that is characteristic of the disease state botulism. Three related peptide-like molecules (PLMs) were designed using previous information from co-crystal structures, synthesized, and assayed for in vitro inhibition against BoNT/A LC. Our results indicate these PLMS are competitive inhibitors of the BoNT/A LC protease and their K(i) values are in the nM-range.

Protein kinase D as a potential new target for cancer therapy.

Protein kinase D is a novel family of serine/threonine kinases and diacylglycerol receptors that belongs to the calcium/calmodulin-dependent kinase superfamily. Evidence has established that specific PKD isoforms are dysregulated in several cancer types, and PKD involvement has been documented in a variety of cellular processes important to cancer development, including cell growth, apoptosis, motility, and angiogenesis. In light of this, there has been a recent surge in the development of novel chemical inhibitors of PKD.

Binding of a small molecule at a protein-protein interface regulates the chaperone activity of hsp70-hsp40.

Heat shock protein 70 (Hsp70) is a highly conserved molecular chaperone that plays multiple roles in protein homeostasis. In these various tasks, the activity of Hsp70 is shaped by interactions with co-chaperones, such as Hsp40. The Hsp40 family of co-chaperones binds to Hsp70 through a conserved J-domain, and these factors stimulate ATPase and protein-folding activity.

Novel protein kinase D inhibitors cause potent arrest in prostate cancer cell growth and motility.

Background: Protein kinase D (PKD) has been implicated in a wide range of cellular processes and pathological conditions including cancer. However, targeting PKD therapeutically and dissecting PKD-mediated cellular responses remains difficult due to lack of a potent and selective inhibitor. Previously, we identified a novel pan-PKD inhibitor, CID755673, with potency in the upper nanomolar range and high selectivity for PKD.

Oxidative lipidomics of hyperoxic acute lung injury: mass spectrometric characterization of cardiolipin and phosphatidylserine peroxidation.

Reactive oxygen species have been shown to play a significant role in hyperoxia-induced acute lung injury, in part, by inducing apoptosis of pulmonary endothelium. However, the signaling roles of phospholipid oxidation products in pulmonary endothelial apoptosis have not been studied. Using an oxidative lipidomics approach, we identified individual molecular species of phospholipids involved in the apoptosis-associated peroxidation process in a hyperoxic lung.

Mitotic slippage in non-cancer cells induced by a microtubule disruptor, disorazole C1.

Background: Disorazoles are polyene macrodiolides isolated from a myxobacterium fermentation broth. Disorazole C1 was newly synthesized and found to depolymerize microtubules and cause mitotic arrest. Here we examined the cellular responses to disorazole C1 in both non-cancer and cancer cells and compared our results to vinblastine and taxol.

Mitochondria as a target in treatment.

Mitochondria are key organelles that perform essential cellular functions and play pivotal roles in cell death and survival signaling. Hence, they represent an attractive target for drugs to treat metabolic, degenerative, and hyperproliferative diseases. Targeting mitochondria with organelle-specific agents or prodrugs has proven to be an effective therapeutic strategy.