Structure-activity Relationships For Inhibition Research Articles

A further pocket or conformational plasticity by mapping COX-1 catalytic site through modified-mofezolac structure-inhibitory activity relationships and their antiplatelet behavior

Cyclooxygenase enzymes have distinct roles in cardiovascular, neurological, and neurodegenerative disease. They are differently expressed in different type of cancers. Specific and selective COXs inhibitors are needed to be used alone or in combo-therapies. Fully understand the differences at the catalytic site of the two cyclooxygenase (COX) isoforms is still opened to investigation. Thus, two series of novel compounds were designed and synthesized in fair to good yields using the highly selective COX-1 inhibitor mofezolac as the lead compound to explore a COX-1 zone formed by the polar residues Q192, S353, H90 and Y355, as well as hydrophobic amino acids I523, F518 and L352. According to the structure of the COX-1:mofezolac complex, hydrophobic amino acids appear to have free volume eventually accessible to the more sterically hindering groups than the methoxy linked to the phenyl groups of mofezolac, in particular the methoxyphenyl at C4-mofezolac isoxazole. Mofezolac bears two methoxyphenyl groups linked to C3 and C4 of the isoxazole core ring. Thus, in the novel compounds, one or both methoxy groups were replaced by the higher homologous ethoxy, normal and isopropyl, normal and tertiary butyl, and phenyl and benzyl. Furthermore, a major difference between the two sets of compounds is the presence of either a methyl or acetic moiety at the C5 of the isoxazole. Among the C5-methyl series, 12 (direct precursor of mofezolac) (COX-1 IC50 = 0.076 μM and COX-2 IC50 = 0.35 μM) and 15a (ethoxy replacing the two methoxy groups in 12; COX-1 IC50 = 0.23 μM and COX-2 IC50 > 50 μM) were still active and with a Selectivity Index (SI = COX-2 IC50/COX-1 IC50) = 5 and 217, respectively. The other symmetrically substituted alkoxyphenyl moietis were inactive at 50 μM final concentration. Among the asymmetrically substituted, only the 16a (methoxyphenyl on C3-isoxazole and ethoxyphenyl on C4-isoxazole) and 16b (methoxyphenyl on C3-isoxazole and n-propoxyphenyl on C4-isoxazole) were active with SI = 1087 and 38, respectively. Among the set of compounds with the acetic moiety, structurally more similar to mofezolac (SI = 6329), SI ranged between 1.4 and 943. It is noteworthy that 17b (n-propoxyphenyl on both C3- and C4-isoxazole) were found to be a COX-2 slightly selective inhibitor with SI = 0.072 (COX-1 IC50 > 50 μM and COX-2 IC50 = 3.6 μM). Platelet aggregation induced by arachidonic acid (AA) can be in vitro suppressed by the synthesized compounds, without affecting of the secondary hemostasia, confirming the biological effect provided by the selective inhibition of COX-1. A positive profile of hemocompatibility in relation to erythrocyte and platelet toxicity was observed. Additionally, these compounds exhibited a positive profile of hemocompatibility and reduced cytotoxicity. Quantitative structure activity relationship (QSAR) models and molecular modelling (Ligand and Structure based virtual screening procedures) provide key information on the physicochemical and pharmacokinetic properties of the COX-1 inhibitors as well as new insights into the mechanisms of inhibition that will be used to guide the development of more effective and selective compounds. X-ray analysis was used to confirm the chemical structure of 14 (MSA17).

Bioactivity and computational studies on the induction of urease inhibition by three Cu(II) complexes with a fluorinated Schiff base and different secondary ligands

Three mononuclear Cu(II) complexes, [Cu(C16H12NO3F)(H2O)] (C1), [Cu(C16H12NO3F)(C10H9N3)]·H2O·0.5CH3OH (C2) and [Cu(C16H12NO3F)(C3H4N2)] (C3) with a fluorinated Schiff base ligand (C16H12NO3F = 5-fluorosalicylaldehyde-L-phenylalanine) and different secondary ligands (C10H9N3 = 2,2′-dipyridylamine; C3H4N2 = imidazole) were synthesized and structurally characterized. Theoretical calculation of the three complexes was carried out by density functional theory (DFT) Becke's three-parameter hybrid (B3LYP) method using the Gaussian 09 package. The calculation results are in accordance with experimental results. In addition, the inhibitory activities of C1-C3 were tested in vitro against jack bean urease. At the same time, molecular docking was investigated to determine the probable binding mode. The experimental values and docking simulation exhibited that C1 showed strong inhibitory activity (IC50 = 0.68 ± 0.09 μM) compared with the positive reference acetohydroxamic acid (IC50 = 27.73 ± 2.93 μM). Moreover, a 100-ns molecular dynamics (MD) simulation was performed to evaluate the stability of urease (PDB ID: 3LA4) and the binding stability of the 3LA4/C1 and 3LA4/C3 using the Desmond 2021 from Schrödinger. Their structure-inhibitory activity relationship was further discussed from the perspective of molecular docking, theoretical calculation and molecular dynamics simulation.

Structure, Function, and Inhibitors of the Mitochondrial Chaperone TRAP1.

Tumor necrosis factor receptor-associated protein 1 (TRAP1) is a mitochondrial molecular chaperone modulating cellular metabolism and signaling pathways by altering the conformation, activity, and stability of numerous substrate proteins called clients. It exerts its chaperone function as an adaptive response to counter cellular stresses instead of maintaining housekeeping protein homeostasis. However, the stress-adaptive machinery becomes dysregulated to support the progression and maintenance of human diseases, such as cancers; therefore, TRAP1 has been proposed as a promising target protein for anticancer drug development. In this review, by collating recent reports on high-resolution TRAP1 structures and structure-activity relationships of inhibitors, we aimed to provide better insights into the chaperoning mechanism of the emerging drug target and to suggest an efficient strategy for the development of potent TRAP1 inhibitors.

Unraveling the Structure-Dependent Inhibitory Effects of Ginsenoside Series Compounds on Human Cytochrome P450 1B1.

Cytochrome P450 1B1(CYP1B1) is an extrahepatic P450 isoenzyme that can participate in processes of undermining the effectiveness and safety of anti-cancer therapy. Ginsenosides are the main active ingredients in ginseng, which possesses rich pharmacological activities, including anti-cancer activity and organ protection. However, the effect of ginsenosides on the activity of CYP1B1 remains unclear. The present study aimed to investigate the inhibitory effect of ginsenosides on CYP1B1 and reveal the structure-inhibitory activity relationship. Firstly, recombinant CYP1B1 and EROD reactions were used to evaluate the inhibitory effect of ginsenosides. Secondly, molecular docking was used to simulate the interactions between ginsenosides and CYP1B1. Finally, the structure-inhibitory activity relationship was analyzed. The ginsenosides, Rb2, Rd, and Rg3, significantly inhibited CYP1B1; the ginsenoside Rd showed the strongest inhibition effect, with a Ki value of 47.37 μM in non-competitive mode. Notably, ginsenoside Rd formed hydrogen bonds with two key amino acid residues of CYP1B1, and one bond was between the glycosyl in position 20 and ALA330, which also made ginsenoside Rd close to the heme iron of CYP1B1. In contrast, ginsenosides, Rb2 and Rg3, which showed weaker inhibition, interacted with only one CYP1B1 residue by the hydrogen bond, which was far away from the heme iron. Finally, the structure-inhibitory activity relationship analysis demonstrated that the number of glycosyls in position 20 and the type of sapogenins in the ginsenoside structure are the key factors determining inhibitory activity. Meanwhile, ALA330 was a vital amino acid in the potent inhibition of CYP1B1 by ginsenosides. A structure-dependent inhibitory effect on CYP1B1 was revealed for ginsenosides, among which ginsenoside Rd showed the strongest inhibition due to its mono-glycosyl in position 20 of the ginsenoside parent structure. These findings would provide evidence for the synthesis of novel CYP1B1 inhibitors to augment the anti-cancer therapeutic effect.

Inhibition of Dipeptidyl Peptidase-4 by Flavonoids: Structure-Activity Relationship, Kinetics and Interaction Mechanism.

With the aim to establish a structure-inhibitory activity relationship of flavonoids against dipeptidyl peptidase-4 (DPP-4) and elucidate the interaction mechanisms between them, a pannel of 70 structurally diverse flavonoids was used to evaluate their inhibitory activities against DPP-4, among which myricetin, hyperoside, narcissoside, cyanidin 3-O-glucoside, and isoliquiritigenin showed higher inhibitory activities in a concentration-dependent manner. Structure-activity relationship analysis revealed that introducing hydroxyl groups to C3', C4', and C6 of the flavonoid structure was beneficial to improving the inhibitory efficacy against DPP-4, whereas the hydroxylation at position 3 of ring C in the flavonoid structure was unfavorable for the inhibition. Besides, the methylation of the hydroxyl groups at C3', C4', and C7 of the flavonoid structure tended to lower the inhibitory activity against DPP-4, and the 2,3-double bond and 4-carbonyl group on ring C of the flavonoid structure was essential for the inhibition. Glycosylation affected the inhibitory activity diversely, depending on the structure of flavonoid aglycone, type of glycoside, as well as the position of substitution. Inhibition kinetic analysis suggested that myricetin reversibly inhibited DPP-4 in a non-competitive mode, whereas hyperoside, narcissoside, cyanidin 3-O-glucoside, and isoliquiritigenin all reversibly inhibited DPP-4 in a mixed type. Moreover, the fluorescence quenching analysis indicated that all the five flavonoid compounds could effectively quench the intrinsic fluorescence of DPP-4 by spontaneously binding with it to form an unstable complex. Hydrogen bonds and van der Waals were the predominant forces to maintain the complex of myricetin with DPP-4, and electrostatic forces might play an important role in stabilizing the complexes of the remaining four flavonoids with DPP-4. The binding of the tested flavonoids to DPP-4 could also induce the conformation change of DPP-4 and thus led to inhibition on the enzyme. Molecular docking simulation further ascertained the binding interactions between DPP-4 and the selected five flavonoids, among which hyperoside, narcissoside, cyaniding 3-O-glucoside, and isoliquiritigenin inserted into the active site cavity of DPP-4 and interacted with the key amino acid residues of the active site, whereas the binding site of myricetin was located in a minor cavity close to the active pockets of DPP-4.

Discovery of a series of 5-phenyl-2-furan derivatives containing 1,3-thiazole moiety as potent Escherichia coli β-glucuronidase inhibitors

Gut microbial β-glucuronidases have drawn much attention due to their role as a potential therapeutic target to alleviate some drugs or their metabolites-induced gastrointestinal toxicity. In this study, fifteen 5-phenyl-2-furan derivatives containing 1,3-thiazole moiety (1–15) were synthesized and evaluated for their inhibitory effects against Escherichia coli β-glucuronidase (EcGUS). Twelve of them showed satisfactory inhibition against EcGUS with IC50 values ranging from 0.25 μM to 2.13 μM with compound 12 exhibited the best inhibition. Inhibition kinetics studies indicated that compound 12 (Ki = 0.14 ± 0.01 μM) was an uncompetitive inhibitor for EcGUS and molecular docking simulation further predicted the binding model and capability of compound 12 with EcGUS. A preliminary structure-inhibitory activity relationship study revealed that the heterocyclic backbone and bromine substitution of benzene may be essential for inhibition against EcGUS. The compounds have the potential to be applied in drug-induced gastrointestinal toxicity and the findings would help researchers to design and develop more effective 5-phenyl-2-furan type EcGUS inhibitors.

Highly Selective Sub-Nanomolar Cathepsin S Inhibitors by Merging Fragment Binders with Nitrile Inhibitors.

Pharmacological inhibition of cathepsin S (CatS) allows for a specific modulation of the adaptive immune system and many major diseases. Here, we used NMR fragment screening and crystal structure-aided merging to synthesize novel, highly selective CatS inhibitors with picomolar enzymatic Ki values and nanomolar functional activity in human Raji cells. Noncovalent fragment hits revealed binding hotspots, while the covalent inhibitor structure-activity relationship enabled efficient potency optimization.

Urease inhibition studies of six Ni(II), Co(II) and Cu(II) complexes with two sexidentate N2O4-donor bis-Schiff base ligands: An experimental and DFT computational study

Six novel complexes, [Ni(C36H34N2O10)]·2.25CH3OH·0.5C4H10O (1), [Co(C36H34N2O10)] (2), [Cu(C36H34N2O10)]·2CH3OH (3), [Ni(C36H32N2O8Cl2)]·2CH3OH (4), [Co(C36H32N2O8Cl2)]·4CH3OH (5) and [Cu(C36H32N2O8Cl2)]·2CH3OH (6) with two sexidentate N2O4-donor bis-Schiff base ligands (C36H34N2O10 = 1,2-bis(2-methoxy-6-formylphenoxy)ethane-l-tyrosine; C36H32N2O8Cl2 = 1,2-bis(2-methoxy-6-formylphenoxy)ethane-l-4-chlorophenylalanine) have been synthesized and structurally characterized. Theoretical calculation of the six complexes was carried out by density functional theory (DFT) Becke's three-parameter hybrid (B3LYP) method employing the 6-3lG basis set, indicating that the calculation results are in accordance with experimental results. Moreover, the inhibitory activities of complexes 1–6 were tested in vitro against jack bean urease. At the same time, molecular docking was investigated to determine the probable binding mode. The experimental values and docking simulation exhibited that complexes 3 and 6 showed strong inhibitory activity (IC50 = 10.36 ± 1.13, 15.63 ± 3.04 μM) compared with the positive reference acetohydroxamic acid (IC50 = 26.99 ± 1.43 μM). Their structure-inhibitory activity relationship was further discussed from the perspective of molecular docking and theoretical calculation.

Translational impact of novel widely pharmacological characterized mofezolac-derived COX-1 inhibitors combined with bortezomib on human multiple myeloma cell lines viability

A set of novel diarylisoxazoles has been projected using mofezolac (1) as a lead compound to investigate structure-inhibitory activity relationships of new compounds and the cyclooxygenases (COXs) catalytic activity. Mofezolac was chosen because is the most potent and selective reversible COX-1 inhibitor [COX-1 IC50 = 0.0079 μM and COX-2 IC50 > 50 μM, with a selectivity index (SI) in favor of COX-1 higher than 6300]. Seventeen new compounds were synthesized in fair to good yields and evaluated for their COXs inhibitory activity and selectivity. SIs ranged between 1 and higher than 1190.3,4-Bis(4-methoxyphenyl)-5-vinylisoxazole (22) has the highest SI with COX-1 IC50 = 0.042 μM and COX-2 IC50 > 50 μM. 1 and 22 were superior to aspirin in inhibiting platelet aggregation (IC50 = 0.45, 0.63 and 1.11 μM, respectively) in human platelet rich plasma (hPRP) assay. They did not induce blood coagulation and hemolysis, and are neither genotoxic nor mutagen. 1 and 22 slightly increase bortezomib cytotoxic effect on multiple myeloma (MM) cell lines (NCI-H929 and RPMI-8226) and affects MM cell cycle and apoptosis when co-administered with the proteasome inhibitor bortezomib, a drug clinically used to treat plasma cell neoplasms including MM. In addition, structure-based binding mode of 1 and 22, through Fingerprints for Ligands and Proteins (FLAG) calculation, allowed to explain the one order of magnitude difference between COX-1 IC50 values of the two compounds. Specifically, the higher inhibitory potency seems due to the formation of a H-bond between COX-1 S530 and the carboxyl, present in 1 and absent in 22.

Design and Potency of Dual Soluble Epoxide Hydrolase/Fatty Acid Amide Hydrolase Inhibitors

Fatty acid amide hydrolase (FAAH) is responsible for regulating concentrations of the endocannabinoid arachidonoyl ethanolamide. Multiple FAAH inhibitors have been developed for clinical trials and have failed to demonstrate efficacy at treating pain, despite promising preclinical data. One approach toward increasing the efficacy of FAAH inhibitors is to concurrently inhibit other targets responsible for regulating pain. Here, we designed dual inhibitors targeting the enzymes FAAH and soluble epoxide hydrolase (sEH), which are targets previously shown to synergize at reducing inflammatory and neuropathic pain. Exploration of the sEH/FAAH inhibitor structure–activity relationship started with PF-750, a FAAH inhibitor (IC50 = 19 nM) that weakly inhibited sEH (IC50 = 640 nM). Potency was optimized resulting in an inhibitor with improved potency on both targets (11, sEH IC50 = 5 nM, FAAH IC50 = 8 nM). This inhibitor demonstrated good target selectivity, pharmacokinetic properties (AUC = 1200 h nM, t1/2 = 4.9 h in mice), and in vivo target engagement.

Facile Solid-Phase Synthesis and Assessment of Nucleoside Analogs as Inhibitors of Bacterial UDP-Sugar Processing Enzymes.

The privileged uptake of nucleosides into cells has generated interest in the development of nucleoside-analog libraries for mining new inhibitors. Of particular interest are applications in the discovery of substrate mimetic inhibitors for the growing number of identified glycan-processing enzymes in bacterial pathogens. However, the high polarity and the need for appropriate protecting group strategies for nucleosides challenges the development of synthetic approaches. Here, we report an accessible, user-friendly synthesis that branches from a common solid phase-immobilized uridinyl-amine intermediate, which can be used as a starting point for diversity-oriented synthesis. We demonstrate the generation of five series of uridinyl nucleoside analogs for investigating inhibitor structure-activity relationships. This library was screened for inhibition of representative enzymes from three functional families including a phosphoglycosyl transferase, a UDP-aminosugar acetyltransferase, and a glycosyltransferase. These candidates were taken from the Gram-negative bacteria Campylobacter concisus and Campylobacter jejuni and the Gram-positive bacterium Clostridium difficile, respectively. Inhibition studies show that specific compound series preferentially inhibit selected enzymes, with IC50 values ranging from 35 ± 7 μM to 174 ± 21 μM. Insights from the screen provide a strong foundation for further structural elaboration, to improve potency, which will be enabled by the same synthetic strategy. The solid-phase strategy was also used to synthesize pseudouridine analogs of lead compounds. Finally, the compounds were found to be nontoxic to mammalian cells, further supporting the opportunities for future development.

Toward More Drug Like Inhibitors of Trypanosome Alternative Oxidase.

New tools are required to ensure the adequate control of the neglected tropical disease human African trypanosomiasis. Annual reports of infection have recently fallen to fewer than 5000 cases per year; however, current therapies are hard to administer and have safety concerns and, hence, are far from ideal. Trypanosome alternative oxidase is an exciting target for controlling the infection; it is unique to the parasite, and inhibition of this enzyme with the natural product ascofuranone has shown to clear in vivo infections. We report the synthesis and associated structure activity relationships of inhibitors based upon this natural product with correlation to T.b.brucei growth inhibition in an attempt to generate molecules that possess improved physicochemical properties and potential for use as new treatments for human African trypanosomiasis.

Synthesis and Structure-Activity Relationships of Inhibitors That Target the C-Terminal MEEVD on Heat Shock Protein 90.

Herein, we describe the synthesis and structure–activity relationships of cyclic peptides designed to target heat shock protein 90 (Hsp90). Generating 19 compounds and evaluating their binding affinity reveals that increasing electrostatic interactions allows the compounds to bind more effectively with Hsp90 compared to the lead structure. Exchanging specific residues for lysine improves binding affinity for Hsp90, indicating some residues are not critical for interacting with the target, whereas others are essential. Replacing l- for d-amino acids produced compounds with decreased binding affinity compared to the parent structure, confirming the importance of conformation and identifying key residues most important for binding. Thus, a specific conformation and electrostatic interactions are required in order for these inhibitors to bind to Hsp90.

A Novel Scaffold for Developing Specific or Broad-Spectrum Chitinase Inhibitors.

Chitinases play important roles in pathogen invasion, arthropod molting, plant defense, and human inflammation. Inhibition of the activity of a typical chitinase by small molecules is of significance in drug development and biological research. On the basis of a recent reported crystal structure of OfChtI, the insect chitinase derived from the pest Ostrinia furnacalis, we computationally identified 17 compounds from a library of over 4 million chemicals by two rounds virtual screening. Among these, three compounds from one chemical class inhibited the activity of OfChtI with single-digit-micromolar IC50 values, and one compound from another chemical class exhibited a broad inhibitory activity not only toward OfChtI but also toward bacterial, fungal, and human chitinases. A new scaffold was discovered, and a structure-inhibitory activity relationship was proposed. This work may provide a novel starting point for the development of specific or broad-spectrum chitinase inhibitors.

Myeloperoxidase as a Target for the Treatment of Inflammatory Syndromes: Mechanisms and Structure Activity Relationships of Inhibitors.

Inflammation is an initial response of the body to a harmful stimuli and it is achieved by the increased movement of leukocytes (especially granulocytes) from blood into injured tissues. It is required for healing wounds and infections. Despite their indispensable role in microbial killing, the inflammation reactions may also cause diseases to a host such as hay fever, atherosclerosis, and rheumatoid arthritis. The enzymes and oxidizing species released during the inflammatory process can cause damages to the host tissues which lead to inflammatory syndromes. The role of myeloperoxidase (MPO) in the inflammatory reactions is well documented. It contributes in killing the pathogens but it is also implicated in several inflammatory syndromes such as Parkinson's disease, Alzheimer's disease and atherosclerosis. Thus, this enzyme has attracted more attention of the scientists and it has become a target for drug designing. In the last decade, several reversible and irreversible MPO inhibitors were identified as very high potent inhibitors such as fluoroalkylindole, aromatic hydroxamic acid, thioxanthine and benzoic acid hydrazide derivatives. In this review, we tried to illustrate the MPO inhibitors and highlight their structure activity relationship (SAR). In this paper we also discussed the mechanism of the inhibitory effect of the most potent compounds.

Facile Modulation of Antibody Fucosylation with Small Molecule Fucostatin Inhibitors and Cocrystal Structure with GDP-Mannose 4,6-Dehydratase.

The efficacy of therapeutic antibodies that induce antibody-dependent cellular cytotoxicity can be improved by reduced fucosylation. Consequently, fucosylation is a critical product attribute of monoclonal antibodies produced as protein therapeutics. Small molecule fucosylation inhibitors have also shown promise as potential therapeutics in animal models of tumors, arthritis, and sickle cell disease. Potent small molecule metabolic inhibitors of cellular protein fucosylation, 6,6,6-trifluorofucose per-O-acetate and 6,6,6-trifluorofucose (fucostatin I), were identified that reduces the fucosylation of recombinantly expressed antibodies in cell culture in a concentration-dependent fashion enabling the controlled modulation of protein fucosylation levels. 6,6,6-Trifluorofucose binds at an allosteric site of GDP-mannose 4,6-dehydratase (GMD) as revealed for the first time by the X-ray cocrystal structure of a bound allosteric GMD inhibitor. 6,6,6-Trifluorofucose was found to be incorporated in place of fucose at low levels (<1%) in the glycans of recombinantly expressed antibodies. A fucose-1-phosphonate analog, fucostatin II, was designed that inhibits fucosylation with no incorporation into antibody glycans, allowing the production of afucosylated antibodies in which the incorporation of non-native sugar is completely absent-a key advantage in the production of therapeutic antibodies, especially biosimilar antibodies. Inhibitor structure-activity relationships, identification of cellular and inhibitor metabolites in inhibitor-treated cells, fucose competition studies, and the production of recombinant antibodies with varying levels of fucosylation are described.

Understanding the Structural Basis of ALDH-2 Inhibition by Molecular Docking.

The ALDH-2 enzyme has been identified as an important therapeutic target for the development of new drugs for the treatment of cocaine addiction. Several studies involving the synthesis, the design and pharmacological evaluation of daidzin (isoflavonoid inhibitor of ALDH-2) analogs were conducted. In this study, we used two in silico approaches effective to understand the mechanism of inhibition of ALDH-2 enzyme, the molecular docking and constructing a pharmacophore model, and we established a correlation between the inhibitory profiles of daidzin and its analog for ALDH-2 and their interaction profiles to understand the structural basis for their inhibitory activities. Docking is efficient and opportune tool to guide the design of new inhibitors of ALDH-2. From the results of the molecular docking studies performed herein and their relationships with the inhibitory profiles of some daidzin analogs described previously in the literature, pharmacophore groups associated with ALDH-2 enzyme recognition were identified. Summarizing our findings, the presence of a linear alkyl chain with a terminal hydrogen bond acceptor group in position 7 is important for the interaction with the Gln-289 residue. Additionally, the presence of a group that is capable of performing hydrogen bonding interactions as either a donor or acceptor in the 4' position is important for the interaction with the Glu-268 residue; this group is the primary pharmacophore that should be attached to the scaffold of the aromatic nucleus of an ideal inhibitor of ALDH-2. The structure inhibitory activity relationships among daidzin analogs were established using a molecular docking tool, thus identifying the structural reasons for the inhibition of the ALDH-2 enzyme. We defined the key pharmacophore groups required for enzyme inhibition and the maintenance of interactions with the amino acids Gln-289 and Glu-268, which are related to the potency of the ALDH-2 inhibitors. This study is highly relevant for the design of new ALDH-2 inhibitors using different medicinal chemistry tools to develop novel therapies for controlling cocaine addiction.

Abstract 1375: Development of synthetic heparan sulfate oligosaccharides as anti-angiogenic agents

Abstract Angiogenesis has been validated as a target in multiple randomised trials in ovarian cancer, in which addition of VEGF pathway inhibitors to conventional cytotoxic treatment resulted in increased progression-free and in some trials overall survival. However, the benefit from VEGF pathway inhibitors is still modest and the redundancy of angiogenic cytokines might be one of the underlying mechanisms. The majority of angiogenic cytokines, such as FGFs, HGF, VEGF165, IL-8, SDF-1α, HB-EGF that are also linked to ovarian cancer, critically depend on the linear glycosaminoglycan, heparan sulfate (HS), for their biological activity. HS is composed of repeating disaccharides that consist of N-substituted glucosamine and a hexuronic acid residue and is bound to core proteins which support signaling complex formation. The critical importance of glucosamine-6-O-sulfate (6S) moieties in assembling the growth factor/receptor signaling complex implies that reduced 6S content in HS will impact angiogenesis and thereby tumor growth. We used chemical synthesis to produce three differentially sulfated dodecasaccharides (12-mers). All three 12-mers were homogeneously sulfated at the 2-O position of iduronate (IS) and the N-position of glucosamine (NS). The first 12-mer lacked 6S moieties ([NSIS]6), the second 12-mer had a single 6S introduced at the non-reducing end of the molecule ([NS6SIS]1-[NSIS]5) and the third 12-mer was uniformly 6-O-sulfated ([NS6SIS]6). Comparison of anti-angiogenic properties of these 12-mers revealed differential inhibitory activities against angiogenic cytokines. While a single 6S at the non-reducing end slightly improved inhibition of FGF2- and VEGF165-induced angiogenic responses when compared to non-6S-sulfated 12-mer, it produced striking changes in the biological effects on IL-8/SDF-1α. Addition of one 6S abolished inhibitory activity of [NSIS]6 against IL-8, but conferred superior activity in inhibition of SDF-1α, in vitro and in vivo. These dramatic differential effects were absent if all glucosamine residues were 6-O-sulfated. NSIS 12-mer with a single 6S inhibited FGF-2-dependent microvessel formation in tumor xenografts, FGFR signaling in tumor blood vessels, but was insufficient in inhibiting tumor growth, most likely due to the dominant role of VEGF. We demonstrate unique structure-activity relationships for inhibition of SDF-1α and IL-8 which opens new opportunities in the development of glycotherapeutics. We show that oligosaccharides can be designed to target multiple or specific angiogenic cytokines, thus demonstrating the feasibility in generating agents that overcome resistance to VEGF inhibitors. Citation Format: Gordon C. Jayson, Steen U. Hansen, Gavin J. Miller, Claire Cole, Graham Rushton, John M. Gardiner, Egle Avizienyte. Development of synthetic heparan sulfate oligosaccharides as anti-angiogenic agents. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1375. doi:10.1158/1538-7445.AM2015-1375

Dithiocarbamates with potent inhibitory activity against the Saccharomyces cerevisiae β-carbonic anhydrase

Dithiocarbamates (DTCs) prepared from primary or secondary amines, which incorporated amino/hydroxyl-alkyl, mono-/bicyclic aliphatic/heterocyclic rings based on the quinuclidine, piperidine, hydroxy-/carboxy-/amino-substituted piperidine, morpholine and piperazine scaffolds, were investigated for the inhibition of α- and β-carbonic anhydrases (CAs, EC 4.2.1.1) of pharmacologic relevance, such as the human (h) isoform hCA I and II, as well as the Saccharomyces cerevisiae β-CA, scCA. The yeast and its β-CA were shown earlier to be useful models of pathogenic fungal infections. The DTCs investigated here were medium potency hCA I inhibitors (KIs of 66.5–910 nM), were more effective as hCA II inhibitors (KIs of 8.9–107 nM) and some of them showed excellent, low nanomolar activity against the yeast enzyme, with inhibition constants ranging between 6.4 and 259 nM. The detailed structure activity relationship for inhibition of the yeast and human enzymes is discussed. Several of the investigated DTCs showed excellent selectivity ratios for inhibiting the yeast over the human cytosolic CA isoforms.

Synthesis and structure-activity-relationship studies of thiazolidinediones as antiplasmodial inhibitors of the Plasmodium falciparum cysteine protease falcipain-2.

Following a structure-based virtual screening, a series of 2,4 thiazolidinediones was synthesized in order to explore structure activity relationships for inhibition of the Plasmodium falciparum cysteine protease falcipain-2 (FP-2) and of whole cell antiparasitic activity. Most compounds exhibited low micromolar antiplasmodial activities against the P. falciparum drug resistant W2 strain. The most active compounds of the series were tested for in vitro microsomal metabolic stability and found to be susceptible to hepatic metabolism. Subsequent metabolite identification studies highlighted the metabolic hot spots. Molecular docking studies of a frontrunner inhibitor were carried out to determine the probable binding mode of this class of inhibitors in the active site of FP-2.