N-Alkyldeoxynojirimycin derivatives with novel terminal tertiary amide substitution for treatment of bovine viral diarrhea virus (BVDV), Dengue,and Tacaribe virus infections

Novel N-alkyldeoxynojirimycins (NADNJs) with two hydrophobic groups attached to a nitrogen linker on the alkyl chain were designed. A novel NADNJ containing a terminal tertiary carboxamide moiety was discovered that was a potent inhibitor against BVDV. Further optimization resulted in a structurally more stable lead compound 24 with a submicromolar EC₅₀ against BVDV, Dengue, and Tacaribe; and low cytotoxicity.     

Carbonic anhydrase inhibitors. Interaction of the antitumor sulfamate EMD 486019 with twelve mammalian carbonic anhydrase isoforms: Kinetic and X-ray crystallographic studies

The new antitumor sulfamate EMD 486019 was investigated for its interaction with twelve catalytically active mammalian carbonic anhydrase (CA, EC 4.2.1.1) isozymes, hCA I – XIV. Similarly to 667-Coumate, a structurally related compound in phase II clinical trials as steroid sulfatase/CA inhibitor with potent antitumor properties, EMD 486019 acts as a strong inhibitor of isozymes CA II, VB, VII, IX, XII, and XIV (K_Is in the range of 13–19 nM) being less effective against other isozymes (K_Is in the range of 66–3600 nM against hCA I, IV, VA, VI, and mCA XIII, respectively). The complete inhibition profile of 667-Coumate against these mammalian CAs is also reported here for the first time. Comparing the X-ray crystal structures of the two adducts of CA II with EMD 486019 and 667-Coumate, distinct orientations of the bound sulfamates within the enzyme cavity were observed, which account for their distinct inhibition profiles. CA II/IX potent inhibitors belonging to the sulfamate class are thus valuable clinical candidates with potential for development as antitumor agents with a multifactorial mechanism of action.     

Discovery and structure–activity relationships of a series of pyroglutamic acid amide antagonists of the P2X7 receptor

A computational lead-hopping exercise identified compound 4 as a structurally distinct P2X₇ receptor antagonist. Structure–activity relationships (SAR) of a series of pyroglutamic acid amide analogues of 4 were investigated and compound 31 was identified as a potent P2X₇ antagonist with excellent in vivo activity in animal models of pain, and a profile suitable for progression to clinical studies.     

A highly predictive 3D-QSAR model for binding to the voltage-gated sodium channel: Design of potent new ligands

A comprehensive comparative molecular field analysis (CoMFA) model for the binding of ligands to the neuronal voltage-gated sodium channel was generated based on 67 diverse compounds. Earlier published CoMFA models for this target provided μM ligands, but the improved model described here provided structurally novel compounds with low nM IC₅₀. For example, new compounds 94 and 95 had IC₅₀ values of 129 and 119 nM, respectively.     

Characterization of the copper(II) binding site in the pink copper binding protein CusF by electron paramagnetic resonance spectroscopy

Electron paramagnetic resonance (EPR) spectroscopy has been used to structurally characterize the copper-binding site in CusF protein from Escherichia coli. The EPR spectra indicate a single type II copper center with parameters typical for nitrogen and oxygen ligands (A~200 G, g~2.186, g~2.051). The pulsed EPR data show that one of the ligands to Cu²⁺ is an imidazole ring of a histidine residue. The remote amino nitrogen of this imidazole ring is readily observed by electron spin-echo envelope modulation spectroscopy, while the imino nitrogen that is directly coordinated to the Cu²⁺ ion is observed by pulsed electron–nuclear double resonance (ENDOR). In addition, the ENDOR spectra reveal the presence of one more nitrogen ligand that was assigned to be a deprotonated peptide nitrogen. Apart from the two nitrogen ligands, it has been established that there are two nearby hydroxyl protons, although whether these belong to a single equatorial water ligand or two equatorial hydroxide ligands is not known.

High-performance liquid chromatographic assay for the determination of the novel etoposide derivative dimethylaminoetoposide (NK611) and its metabolites in urine of cancer patients

A simple, reproducible and specific urine assay for the novel epipodophyllotoxin derivative dimethylaminoetoposide (NK611, I) its picro form (III), the N-demethyl metabolite (II) and its picro form (IV) is reported. The method involves the addition of Pr-NK611 as internal standard, chloroform extraction and HPLC separation on a Nova-Pak C₁₈ column with a mobile phase of acetonitrile-0.05 M KH₂PO₄ (pH 6.4) (23:77, v/v). UV detection was used with absorbance monitored at 205 nm and the limit of quantification was 100 ng/ml. The intra- and inter-day precisions were within the ranges 1.1–3.4% and 1.9–2.4% for all analytes and the accuracy was 101–107%. The extraction recovery was more than 88% for I, II and IV and more than 83% for III. The assay is applicable to the urinary monitoring of I–IV in clinical pharmacokinetic investigations.     

Synthesis of oxalamide and triazine derivatives as a novel class of hybrid 4-aminoquinoline with potent antiplasmodial activity

Frequency of malaria and its resistance to chemotherapeutic options are emerging rapidly. To counter this problem, a series of 4-aminoquinolines having oxalamide and triazine functionalities in the side chain were synthesized and screened for their antimalarial activities. Triazine derivative 48 found to be the most active against CQ sensitive strain 3D7 of Plasmodium falciparum in an in vitro assay with an IC₅₀ of 5.23 ng/mL and oxalamide derivative 13 showed an in vivo suppression of 70.45% on day 4 against CQ resistant strain N-67 of Plasmodium yoelii.     

Design,synthesis and biological studies of novel tubulin inhibitors

A series of compounds originally derived from the vascular endothelial growth factor receptor tyrosine kinase inhibitor, SU5416, were synthesized and evaluated. The most potent compound in this series, compound 3, which structurally resembles the potent anti-microtubule agent combretastatin A-4, inhibited tubulin polymerization and showed potent growth inhibitory activities on both prostate and breast cancer lines with IC₅₀ values in the low nanomolar range.     

Radiosynthesis and in vivo evaluation of a fluorine-18 labeled pyrazine based radioligand for PET imaging of the adenosine A2B receptor

On the basis of a pyrazine core structure, three new adenosine A_2B receptor ligands (7a–c) were synthesized containing a 2-fluoropyridine moiety suitable for ¹⁸F-labeling. Compound 7a was docked into a homology model of the A_2B receptor based on X-ray structures of the related A_2A receptor, and its interactions with the adenosine binding site were rationalized. Binding affinity data were determined at the four human adenosine receptor subtypes. Despite a rather low selectivity regarding the A₁ receptor, 7a was radiolabeled as the most suitable candidate (K_i(A_2B)?=?4.24?nM) in order to perform in vivo studies in mice with the aim to estimate fundamental pharmacokinetic characteristics of the compound class. Organ distribution studies and a single PET study demonstrated brain uptake of [¹⁸F]7a with a standardized uptake value (SUV) of ≈1 at 5?min post injection followed by a fast wash out. Metabolism studies of [¹⁸F]7a in mice revealed the formation of a blood–brain barrier penetrable radiometabolite, which could be structurally identified. The results of this study provide an important basis for the design of new derivatives with improved binding properties and metabolic stability in vivo.     

Anti-influenza active and low toxic N-phenyl-substituted β-amidoamidines structurally related to natural antibiotic amidinomycin

A set of racemic N-phenyl-substituted β-amidoamidines hydrochlorides 4, which are structurally related to natural antiviral agent amidinomycin (1), was synthesized in four steps starting from methacryloyl anilide (5). In the final step of the synthetic route, an uncommon monoacylation of β-aminoamidine 8 at the less reactive β-phenylamino-group took place. To rationalize this result, a mechanism which involves initial acylation at the more active amidine-function followed by intramolecular acyl-group transfer to β-phenylamino-group was suggested. All three β-amidoamidines 4d–f bearing long linear aliphatic chain (from n-C₈H₁₇ to n-C₁₂H₂₅) revealed significant in vitro activity against influenza A virus (H3N2) and modest cytotoxicity. The in vitro antiviral potency of 4d,e is 6–20 times greater than that of commercial rimantadine with lower EC₅₀ values and higher therapeutic index. The non-toxic in vivo compounds 4d–f showed a beneficial protective effect in influenza A (H3N2) infected mice.     

Synthesis and evaluation of apoptosis induction of thienopyrimidine compounds on KRAS and BRAF mutated colorectal cancer cell lines

Monoclonal antibodies (MoAb) and tyrosine kinase inhibitors (TKI) targeting the EGFR (Epidermal Growth Factor Receptor) pathways are currently used in colorectal cancer treatment. Despite the improvement of median overall survival, resistance is observed notably due to KRAS and BRAF gene mutations. We synthesized four series of thienopyrimidines whose scaffold is structurally close to TKI used in clinical practice. We evaluated apoptosis induced by these compounds using flow cytometry on KRAS and BRAF mutated cell lines. Our results confirm that the mutated cell lines (HCT116 and HT29) are more resistant to apoptosis than the non-mutated cell line (Hela). Interestingly, among the 13 compounds tested, three of them (5b, 6b and 6d) and gefitinib exhibited a noteworthy pro-apoptotic effect, especially on mutated cell lines with an IC₅₀ value between 70 and 110 μM. These three compounds seem particularly attractive for the development of novel treatments for colorectal cancer patients harboring EGFR pathway mutations.     

Evaluation of andrographolide-based analogs derived from Andrographis paniculata against Mythimna separata Walker and Tetranychus cinnabarinus Boisduval

To discover new natural-product-based pesticides, we structurally modified andrographolide, a labdane diterpenoid isolated from Andrographis paniculata, and stereoselectively prepared a series of 12α-(substituted)benzylamino-14-deoxyandrographolide derivatives (I–V). Three-dimensional structures of compounds 3c, 3d, IIIa and IIIb were further determined by single-crystal X-ray diffraction. Compounds IIa (R¹ = n-C₃H₇, R² = PhCH₂) exhibited more promising insecticidal activity against Mythimna separata than toosendanin. Compounds 3a (R¹ = H), Ib (R¹ = H, R² = 4-ClPhCH₂), and IVa (R¹ = 4-ClPh, R² = PhCH₂) showed potent acaricidal activity against Tetranychus cinnabarinus.     

New quinoline NK3 receptor antagonists with CNS activity

Lead optimisation starting from the previously reported selective quinoline NK₃ receptor antagonists talnetant 2 (SB-223412) and 3 (SB-222200) led to the identification of 3-aminoquinoline NK₃ antagonist 10 (GSK172981) with excellent CNS penetration. Investigation of a structurally related series of sulfonamides with reduced lipophilicity led to the discovery of 20 (GSK256471). Both 10 and 20 are high affinity, potent NK₃ receptor antagonists which despite having different degrees of CNS penetration produced excellent NK₃ receptor occupancy in an ex vivo binding study in gerbil cortex.     

Discovery of novel pyrazolo[1,5-a]pyridine-based EP1 receptor antagonists by scaffold hopping: Design,synthesis, and structure-activity relationships

A scaffold-hopping strategy towards a new pyrazolo[1,5-a]pyridine based core using molecular hybridization of two structurally distinct EP₁ antagonists, followed by structure-activity relationship-guided optimization, resulted in the identification of potent EP₁ antagonists exemplified by 4c, 4f, and 4j, which were shown to reduce pathological intravesical pressure in rats when administered at 1 mg/kg iv.     

Stereoselective synthesis of desloratadine derivatives as antagonist of histamine

A series of desloratadine derivatives were stereoselectively synthesized and evaluated for H₁ antihistamine activity. For the evaluation of H₁ antihistamine activity, the in vitro histamine-induced contraction of the guinea-pig ileum assay (HC) was used. The synthesized desloratadine derivatives 7, 8 and 9 are structurally related to rupatadine and were generated by replacement of the 5-methyl-3-pyridine group of rupatadine with γ-alkylidene butenolide. Their H₁ antihistamine activities have shown a high dependence on the exact nature of the substituent in the lactone ring. Optimum structures 7, 8a and 8g display potent activity inhibiting histamine-induced effects.     

Discovery of disubstituted phenanthrene imidazoles as potent,selective and orally active mPGES-1 inhibitors

Phenanthrene imidazoles 26 and 44 have been identified as novel potent, selective and orally active mPGES-1 inhibitors. These inhibitors are significantly more potent than the previously reported chlorophenanthrene imidazole 1 (MF63) with a human whole blood IC₅₀ of 0.20 and 0.14 μM, respectively. It exhibited a significant analgesic effect in a guinea pig hyperalgesia model at oral doses as low as 14 mg/kg. Both active and selective mPGES-1 inhibitors (26 and 44) have a relatively distinct pharmacokinetic profile and are suitable for clinical development.     

Discovery of aryl ureas and aryl amides as potent and selective histamine H3 receptor antagonists for the treatment of obesity (Part I)

A series of structurally novel aryl ureas was derived from optimization of the HTS lead as selective histamine H₃ receptor (H₃R) antagonists. The SAR was explored and the data obtained set up the starting point and foundation for further optimization. The most potent tool compounds, as exemplified by compounds 2l, 5b, 5d, and 5e, displayed antagonism potencies in the subnanomolar range in in vitro human-H₃R FLIPR assays and rhesus monkey H₃R binding assays.     

Concise synthesis of 4-methylumbelliferyl-penta-N-acetylchitopentaoside and its inhibition effect on chitinase

The synthesis of 4-methylumbelliferyl (UMB)-penta-N-acetylchitopentaoside 4 and its inhibition effect on chitinase are described. The fluorophore-assisted carbohydrate electrophoresis (FACE) analysis showed that the partially N-acetylated chitooligosaccharide (COS) mixture mainly contained glucosamine (GlcN) and oligomers [(GlcN)_n, n = 2–7]. The peracetylated COSs [(GlcNAc)_n, n = 1–7] were synthesized by treating the partially N-acetylated COS mixture with Ac₂O–NaOAc. The peracetylated chitopentaoside 1 was obtained by isolation of peracetylated COS mixture. The peracetylated UMB chitopentaoside 3 was synthesized by treating compound 1 with 4-methylumbelliferone and a Lewis acid (SnCl₄) catalyst. NaOMe in dry methanol was used for deacetylation of the blocked derivative, to give the target compound 4 in an overall yield of 32%. In binding chitinase assay, it indicates that compound 4 is much more stable than the corresponding penta-N-acetylchitopentaose 2.     

EGFR inhibitors from cancer to inflammation: Discovery of 4-fluoro-N-(4-(3-(trifluoromethyl)phenoxy)pyrimidin-5-yl)benzamide as a novel anti-inflammatory EGFR inhibitor

EGFR inhibitors are well-known as anticancer agents. Quite differently, we report our effort to develop EGFR inhibitors as anti-inflammatory agents. Pyrimidinamide EGFR inhibitors eliciting low micromolar IC₅₀ and the structurally close non-EGFR inhibitor urea analog were synthesized. Comparing their nitric oxide (NO) production inhibitory activity in peritoneal macrophages and RAW 246.7 macrophages indicated that their anti-inflammatory activity in peritoneal macrophages might be a sequence of EGFR inhibition. Further evaluations proved that compound 4d significantly and dose-dependently inhibits LPS-induced iNOS expression and IL-1β, IL-6, and TNF-α production via NF-κB inactivation in peritoneal macrophages. Compound 4d might serve as a lead compound for development of a novel class of anti-inflammatory EGFR inhibitors.     

Conformational flexibility in the molecular structure of rotenone, a naturally occurring insecticide

The crystal and molecular structure of rotenone, a naturally occurring insecticide with mitochondrial and mitotic spindle inhibitory properties, was determined by direct methods. The crystals were orthorhombic, space group, P2_I2_I2_I with two molecules in the asymmetric unit; a = 8.413 (1) Å, b = 19.840(1), c = 23.581(1), V = 3936 ų, Z = 8. The structure was refined by least-squares methods to a final R = 0.067. The two molecules in the asymmetric unit have different conformations about the junction between the nonaromatic rings B and C. Ring B is in a sofa conformation in both molecules, with a slight distortion toward a half-chair in I, but with C8 and C8′ on opposite sides of the planar part of the rings. This difference in conformation results in I having an extended (linear) shape while II is V-shaped. The more elongated conformation of the molecule (I) has not been reported in previous studies. Ring C also has opposite conformations in the two molecules. The angle between the planes formed by rings A and D in molecule I is 64.3°, while in molecule II it is 88.3°. Molecular mechanics techniques were used to determine the energy of the two conformations. These calculations, at room temperature, predict molecule II to be the more stable conformer. The highly flexible site in the B/C ring junction is also chemically very reactive. This flexibility and reactivity are further discussed in terms of rotenone's inhibitory activities.