Totally found 1145 items.

  • [期刊] Achiral Derivatives of Hydroxamate AR-42 Potently Inhibit Class I HDAC Enzymes and Cancer Cell Proliferation
    AR-42 is an orally active inhibitor of histone deacetylases (HDACs) in clinical trials for multiple myeloma, leukemia, and lymphoma. It has few hydrogen bond donors and acceptors but is a chiral 2-arylbutyrate and potentially prone to racemization. We report achiral AR-42 analogues incorporating a cycloalkyl group linked via a quaternary carbon atom, with up to 40-fold increased potency against human class I HDACs (e.g., JT86, IC50 0.7 nM, HDAC1), 25-fold increased cytotoxicity against five human cancer cell lines, and up to 70-fold less toxicity in normal human cells. JT86 was ninefold more potent than racAR-42 in promoting accumulation of acetylated histone H4 in MM96L melanoma cells. Molecular modeling and structure-activity relationships support binding to HDAC1 with tetrahydropyran acting as a hydrophobic shield from water at the enzyme surface. Such potent inhibitors of class I HDACs may show benefits in diseases (cancers, parasitic infections, inflammatory conditions) where AR-42 is active.
  • [期刊] Non-naturally Occurring Regio Isomer of Lysophosphatidylserine Exhibits Potent Agonistic Activity toward G Protein-Coupled Receptors
    Lysophosphatidylserine (LysoPS), an endogenous ligand of G protein-coupled receptors, consists of L-serine, glycerol, and fatty acid moieties connected by phosphodiester and ester linkages, respectively. An ester linkage of phosphatidylserine can be hydrolyzed at the 1-position or at the 2-position to give 2-acyl lysophospholipid or 1-acyl lysophospholipid, respectively. 2-Acyl lysophospholipid is in nonenzymatic equilibrium with 1-acyl lysophospholipid in vivo. On the other hand, 3-acyl lysophospholipid is not found, at least in mammals, raising the question of whether the reason for this might be that the 3-acyl isomer lacks the biological activities of the other isomers. Here, to test this idea, we designed and synthesized a series of new 3-acyl lysophospholipids. Structure- activity relationship studies of more than 100 "glycol surrogate" derivatives led to the identification of potent and selective agonists for LysoPS receptors GPR34 and P2Y10. Thus, the non-natural 3-acyl compounds are indeed active and appear to be biologically orthogonal with respect to the physiologically relevant 1- and 2-acyl lysophospholipids.
  • [期刊] Cyclic Derivative of Host-Defense Peptide IDR-1018 Improves Proteolytic Stability, Suppresses Inflammation, and Enhances In Vivo Activity
    Host-defense peptides have drawn significant attention as new drugs or drug adjuvants to combat multidrug-resistant bacteria. In this study, we report the development of cyclic derivatives of the immunomodulatory and antibiofilm innate defense regulator peptide (IDR)-1018 based on three different synthetic strategies including head-to-tail cyclization (C1), side-chain-to-tail cyclization (C2), and a disulfide bond cross-linkage (C3). The generated mimetics showed enhanced proteolytic stability and reduced aggregation in vitro and in vivo. The C2 derivative exhibited exceptional ability to suppress inflammation and significantly reduce bacterial loads in a high-density Staphylococcus aureus murine skin infection model. The findings describe different routes to the creation of enzymatically stable mimetics of IDR-1018 and identify a promising new cyclic analogue against bacterial infections.
  • [期刊] 2-Substituted alpha,beta-Methylene-ADP Derivatives: Potent Competitive Ecto-5'-nucleotidase (CD73) Inhibitors with Variable Binding Modes
    CD73 inhibitors are promising drugs for the (immuno)therapy of cancer. Here, we present the synthesis, structure-activity relationships, and cocrystal structures of novel derivatives of the competitive CD73 inhibitor alpha,beta-methylene-ADP (AOPCP) substituted in the 2-position. Small polar or lipophilic residues increased potency, 2-iodo- and 2-chloro-adenosine-5'-O[(phosphonomethyl)phosphonic acid] (15, 16) being the most potent inhibitors with K-i values toward human CD73 of 3-6 nM. Subject to the size and nature of the 2-substituent, variable binding modes were observed by X-ray crystallography. Depending on the binding mode, large species differences were found, e.g., 2-piperazinyl-AOPCP (21) was >12-fold less potent against rat CD73 compared to human CD73. This study shows that high CD73 inhibitory potency can be achieved by simply introducing a small substituent into the 2-position of AOPCP without the necessity of additional bulky N-6-substituents. Moreover, it provides valuable insights into the binding modes of competitive CD73 inhibitors, representing an excellent basis for drug development.
  • [期刊] alpha-Helix-Mimicking Sulfono-gamma-AApeptide Inhibitors for p53-MDM2/MDMX Protein-Protein Interactions
    The use of peptidomimetic scaffolds is a promising strategy for the inhibition of protein-protein interactions (PPIs). Herein, we demonstrate that sulfono-gamma-AApeptides can be rationally designed to mimic the p53 alpha-helix and inhibit p53 MDM2 PPIs. The best inhibitor, with K-d and IC50 values of 26 nM and 0.891 mu M toward MDM2, respectively, is among the most potent unnatural peptidomimetic inhibitors disrupting the p53-MDM2/MDMX interaction. Using fluorescence polarization assays, circular dichroism, nuclear magnetic resonance spectroscopy, and computational simulations, we demonstrate that sulfono-gamma-AApeptides adopt helical structures resembling p53 and competitively inhibit the p53-MDM2 interaction by binding to the hydrophobic cleft of MDM2. Intriguingly, the stapled sulfono-gamma-AApeptides showed promising cellular activity by enhancing p53 transcriptional activity and inducing expression of MDM2 and p21. Moreover, sulfono-gamma-AApeptides exhibited remarkable resistance to proteolysis, augmenting their biological potential. Our results suggest that sulfono-gamma-AApeptides are a new class of unnatural helical foldamers that disrupt PPIs.
  • [期刊] Anti-HIV-Active Nucleoside Triphosphate Prodrugs
    We disclose a study on nucleoside triphosphate (NTP) analogues in which the gamma-phosphate is covalently modified by two different biodegradable masking units and d4T as nucleoside analogue that enable the delivery of d4TTP with high selectivity in phosphate buffer (pH 7.3) and by enzyme-triggered reactions in human CD4(+) T-lymphocyte CEM cell extracts. This allows the bypass of all steps normally needed in the intracellular phosphorylation. These TriPPPro-nucleotides comprising an acyloxybenzyl (AB; ester) or an alkoxycarbonyloxybenzyl (ACB; carbonate) in combination with an ACB moiety are described as NTP delivery systems. The introduction of these two different groups led to the selective formation of gamma-(ACB)-d4TTPs by chemical hydrolysis and in particular by cell extract enzymes. gamma-(AB)-d4TTPs are faster cleaved than gamma-(ACB)-d4TTPs. In antiviral assays, the compounds are highly active against HIV-1 and HIV-2 in wild-type CEM/O cells and more importantly in thymidine kinase-deficient CD4(+) T-cells (CEM/TK-).
  • [期刊] Cationic Versus Anionic Phthalocyanines for Photodynamic Therapy: What a Difference the Charge Makes
    The literature reports on cationic and anionic phthalocyanines (Pcs) for photodynamic therapy suggest systematically significant differences in activity. In this work, ten different zinc(II) Pcs with carboxylate functions or quaternary nitrogens (hydrophilic anionic, hydrophilic cationic, amphiphilic anionic, and amphiphilic cationic) were investigated, with the aim of revealing reasons for such differences. In vitro assays on HeLa, MCF-7, and HCT-116 cells confirmed higher photoactivity for cationic Pcs (EC50 similar to 3-50 nM) than for anionic Pcs (EC50 similar to 0.3-10 mu M), the latter being additionally significantly more active in serum-free medium. The environmental pH, binding to serum proteins, interaction with biomembranes, differences in subcellular localization, and relocalization after irradiation were found to be the main factors contributing to the generally lower photoactivity of anionic Pcs than that of the cationic derivatives. This result is not limited only to the presented derivatives and should be considered in the design of novel photosensitizers.
  • [期刊] Structural Studies on the Inhibitory Binding Mode of Aromatic Coumarinic Esters to Human Kallikrein-Related Peptidase 7
    The serine protease kallikrein-related peptidase 7 (KLK7) is a member of the human tissue kallikreins. Its dysregulation leads to pathophysiological inflammatory processes in the skin. Furthermore, it plays a role in several types of cancer. For the treatment of KLK7-associated diseases, coumarinic esters have been developed as small-molecule enzyme inhibitors. To characterize the inhibition mode of these inhibitors, we analyzed structures of the inhibited protease by X-ray crystallography. Electron density shows the inhibitors covalently attached to His57 of the catalytic triad. This confirms the irreversible character of the inhibition process. Upon inhibitor binding, His57 undergoes an outward rotation; thus, the catalytic triad of the protease is disrupted. Besides, the halophenyl moiety of the inhibitor was absent in the final enzyme-inhibitor complex due to the hydrolysis of the ester linkage. With these results, we analyze the structural basis of KLK7 inhibition by the covalent attachment of aromatic coumarinic esters.
  • [期刊] Synthesis and Structure-Activity Relationship Studies of C2-Modified Analogs of the Antimycobacterial Natural Product Pyridomycin
    A series of derivatives of the antimycobacterial natural product pyridomycin have been prepared with the C2 side chain attached to the macrocyclic core structure by a C-C single bond, in place of the synthetically more demanding enol ester double bond found in the natural product. Hydrophobic C2 substituents of sufficient size generally provide for potent anti-Mtb activity of these dihydropyridomycins (minimum inhibitory concentration (MIC) values around 2.5 mu M), with several analogs thus approaching the activity of natural pyridomycin. Surprisingly, some of these compounds, in contrast to pyridomycin, are insensitive to overexpression of InhA in Mycobacterium tuberculosis (Mtb). This indicates that their anti-Mtb activity does not critically depend on the inhibition of InhA and that their overall mode of action may differ from that of the original natural product lead.
  • [期刊] Metabolic Activation of Pirfenidone Mediated by Cytochrome P450s and Sulfotransferases
    Pirfenidone is approved for the treatment of idiopathic pulmonary fibrosis. Idiosyncratic drug reactions, due to clinical application of pirfenidone, have been documented, even along with death cases resulting from acute liver failure. The present study aimed at the investigation of metabolic activation of pirfenidone possibly participating in the reported adverse reactions. Pirfenidone-derived glutathione/N-acetylcysteine (GSH/NAC) conjugates were detected in microsomal/primary hepatocyte incubations after exposure to pirfenidone. The GSH/NAC conjugates were also observed in bile and urine of rats given pirfenidone, respectively. The observation of the conjugates suggests the formation of a quinone methide intermediate derived from pirfenidone. The intermediate was possibly generated through two pathways. First, pirfenidone was directly metabolized to the quinone methide intermediate via dehydrogenation; second, pirfenidone was oxidized to 5-hydroxymethyl pirfenidone, followed by sulfation to a benzyl alcohol-sulfate derivative. The findings facilitate the understanding of the mechanisms of pirfenidone-induced idiosyncratic toxicity and assist medicinal chemists to minimize toxicities in the development of new pharmaceutical agents.