Design, synthesis, and evaluation of potential inhibitors of nitric oxide synthase

A Novel Prodrug of a nNOS Inhibitor with Improved Pharmacokinetic Potential

Under different pathological conditions, aberrant induction of neuronal nitric oxide synthase (nNOS) generates overproduction of NO that can cause irreversible cell damage. The aim of this study was to develop an amidoxime prodrug of a potent nNOS inhibitor, the benzhydryl acetamidine. We synthesized the benzhydryl acetamidoxime, which was evaluated in vitro to ascertain the potential NOS inhibitory activity, as well as conducting bioconversion into the parent acetamidine. The prodrug was also profiled for in vitro physicochemical properties, by determining the lipophilicity, passive permeation through the human gastrointestinal tract and across the blood-brain barrier by PAMPA, and chemical, enzymatic, and plasma stability. The obtained data demonstrate that the amidoxime prodrug shows an improved pharmacokinetic profile with respect to the acetamidine nNOS inhibitor, thus suggesting that it could be a promising lead compound to treat all those pathological conditions in which nNOS activity is dysregulated.

Thiadiazoline- and Pyrazoline-Based Carboxamides and Carbothioamides: Synthesis and Inhibition against Nitric Oxide Synthase

Two new families of pyrazoline and thiadiazoline heterocycles have been developed. Their inhibitory activities against two different isoforms of nitric oxide synthase (inducible and neuronal NOS) are reported. The novel derivatives were synthesized combining the arylthiadiazoline or arylpyrazoline skeleton and a carboxamide or carbothioamide moiety, used as starting material ethyl 2-nitrobenzoates or substituted nitrobenzaldehydes, respectively. The structure-activity relationships of final molecules are discussed in terms of the R1 radical effects in the aromatic ring, the Y atom in the heterocyclic system, the X heteroatom in the main chain, and the R2 substituent in the carboxamide or carbothioamide rest. In general, thiadiazolines (5a–e) inhibit preferentially the neuronal isoform; among them, 5a is the best nNOS inhibitor (74.11% at 1 mM, IC50 = 420 μM). In contrast, pyrazolines (6a–r) behave better as iNOS than nNOS inhibitors, 6m being the best molecule of this series (76.86% at 1 mM of iNOS inhibition, IC50 = 130 μM) and the most potent of all tested compounds.

Hybridizing Feature Selection and Feature Learning Approaches in QSAR Modeling for Drug Discovery

Quantitative structure-activity relationship modeling using machine learning techniques constitutes a complex computational problem, where the identification of the most informative molecular descriptors for predicting a specific target property plays a critical role. Two main general approaches can be used for this modeling procedure: feature selection and feature learning. In this paper, a performance comparative study of two state-of-art methods related to these two approaches is carried out. In particular, regression and classification models for three different issues are inferred using both methods under different experimental scenarios: two drug-like properties, such as blood-brain-barrier and human intestinal absorption, and enantiomeric excess, as a measurement of purity used for chiral substances. Beyond the contrastive analysis of feature selection and feature learning methods as competitive approaches, the hybridization of these strategies is also evaluated based on previous results obtained in material sciences. From the experimental results, it can be concluded that there is not a clear winner between both approaches because the performance depends on the characteristics of the compound databases used for modeling. Nevertheless, in several cases, it was observed that the accuracy of the models can be improved by combining both approaches when the molecular descriptor sets provided by feature selection and feature learning contain complementary information.

Crystal structure of (Z)-3-(adamantan-1-yl)-1-(3-chlorophenyl)-S-benzylisothiourea, C24H27ClN2S

C24H27ClN2S, triclinicP1̅ (no. 2),a= 7.1670(3) Å,b= 12.2734(6) Å,c= 13.1560(6) Å,α= 109.605(2)°,β= 96.515(2)°,γ= 97.312(2)°,V= 1066.08(8) Å3,Z= 2,Rgt(F)= 0.0515,wRref(F2) = 0.1396,T= 296(2) K.

Adamantane-Isothiourea Hybrid Derivatives: Synthesis, Characterization, In Vitro Antimicrobial, and In Vivo Hypoglycemic Activities

A new series of adamantane-isothiourea hybrid derivatives, namely 4-arylmethyl (Z)-N'-(adamantan-1-yl)-morpholine-4-carbothioimidates 7a-e and 4-arylmethyl (Z)-N'-(adamantan-1-yl)-4-phenylpiperazine-1-carbothioimidates 8a-e were prepared via the reaction of N-(adamantan-1-yl)morpholine-4-carbothioamide 5 and N-(adamantan-1-yl)-4-phenylpiperazine-1-carbothioamide 6 with benzyl or substituted benzyl bromides, in acetone, in the presence of anhydrous potassium carbonate. The structures of the synthesized compounds were confirmed by ¹H-NMR, ¹³C-NMR, electrospray ionization mass spectral (ESI-MS) data, and X-ray crystallographic data. The in vitro antimicrobial activity of the new compounds was determined against certain standard strains of pathogenic bacteria and the yeast-like pathogenic fungus Candida albicans. Compounds 7b, 7d and 7e displayed potent broad-spectrum antibacterial activity, while compounds 7a, 7c, 8b, 8d and 8e were active against the tested Gram-positive bacteria. The in vivo oral hypoglycemic activity of the new compounds was carried on streptozotocin (STZ)-induced diabetic rats. Compounds 7a, 8ab, and 8b produced potent dose-independent reduction of serum glucose levels, compared to the potent hypoglycemic drug gliclazide.

Synthesis and biological activity of two pregnane derivatives with a triazole or imidazole ring at C-21

Pregnane derivatives are studied as agents for the treatment of different hormone-dependent diseases. The biological importance of these steroids is based on their potential use against cancer. In this study, we report the synthesis, characterization and biological activity of two pregnane derivatives with a triazole (3β-hydroxy-21-(1H-1,2,4-triazol-1-yl)pregna-5,16-dien-20-one; T-OH) or imidazole (3β-hydroxy-21-(1H-imidazol-1-yl)pregna-5,16-dien-20-one; I-OH) moieties at C-21. These derivatives were synthesized from 16-dehydropregnenolone acetate. The activity on cell proliferation of the compounds was measured on three human cancer cells lines: prostate cancer (PC-3), breast cancer (MCF7) and lung cancer (SK-LU-1). The cytotoxic and antiproliferative effects of T-OH and I-OH were assessed by using SBR and XTT methods, respectively. The gene expressions were evaluated by real time PCR. In addition, results were complemented by docking studies and transactivation assays using an expression vector to progesterone and androgen receptor. Results show that the two compounds inhibited the three cell lines proliferation in a dose-dependent manner. Compound I-OH downregulated the gene expression of the cyclins D1 and E1 in PC-3 and MFC7 cells; however, effect upon Ki-67, EAG1, BIM or survivin genes was not observed. Docking studies show poor interaction with the steroid receptors. Nevertheless, the transactivation assays show a weak antagonist effect of I-OH on progesterone receptor but not androgenic or antiandrogenic actions. In conclusion, the synthesized compounds inhibited cell proliferation as well as genes key to cell cycle of PC-3 and MCF7 cell lines. Therefore, these compounds could be considered a good starting point for the development of novel therapeutic alternatives to treat cancer.

Etude structurale et vibrationnelle d'un nouveau composé complexe de cobalt: [Co(imidazole)4Cl]Cl

In the title complex, chlorido-tetra-kis-(1H-imidazole-κN (3))cobalt(II) chloride, [CoCl(C3H4N2)4]Cl, the Co(II) cation has a distorted square-pyramidal coordination environment. It is coordinated by four N atoms of four imidazole (Im) groups in the basal plane, and by a Cl atom in the apical position. It is isostructural with [Cu(Im)4Cl]Cl [Morzyk-Ociepa et al. (2012 ▸). J. Mol. Struct. 1028, 49-56] and [Cu(Im)4Br]Br [Hossaini Sadr et al. (2004 ▸). Acta Cryst. E60, m1324-m1326]. In the crystal, the [CoCl(C3H4N2)4](+) cations and Cl(-) anions are linked via N-H⋯Cl hydrogen bonds, forming layers parallel to (010). These layers are linked via C-H⋯Cl hydrogen bonds and C-H⋯π and π-π [inter-centroid distance = 3.794 (2) Å] inter-actions, forming a three-dimensional framework. The IR spectrum shows vibrational bands typical for imidazol groups. The monoclinic unit cell of the title compound emulates an ortho-rhom-bic cell as its β angle is close to 90°. The crystal is twinned, with the refined ratio of twin components being 0.569 (1):0.431 (1).

The impact of structural modification of 1,2,4-thiadiazole derivatives on thermodynamics of solubility and hydration processes

The influence of a structural modification on thermodynamic aspects of solubility and hydration processes of 1,2,4-thiadiazole drug-like compounds was investigated.

2,4,5-Triphenyl-1-(prop-2-en-1-yl)-1H-imidazole

In the title compound, C24H20N2, one of the ring C atoms and one of the ring N atoms are disordered over two sets of sites in a 0.615 (3):0.385 (3) ratio. The two parts of the disordered imidazole ring adopt an envelope conformation, with the undisordered ring N atom as the flap, displaced by -0.118 (6) and 0.226 (7) Å, respectively, in the two disorder components from the plane through the other ring atoms. The crystal structure features C-H⋯N hydrogen bonds and C-H⋯π inter-actions, which lead to the formation of infinite chains along [010].

Identification in silico and experimental validation of novel phosphodiesterase 7 inhibitors with efficacy in experimental autoimmune encephalomyelitis mice

A neural network model has been developed to predict the inhibitory capacity of any chemical structure to be a phosphodiesterase 7 (PDE7) inhibitor, a new promising kind of drugs for the treatment of neurological disorders. The numerical definition of the structures was achieved using CODES program. Through the validation of this neural network model, a novel family of 5-imino-1,2,4-thiadiazoles (ITDZs) has been identified as inhibitors of PDE7. Experimental extensive biological studies have demonstrated the ability of ITDZs to inhibit PDE7 and to increase intracellular levels of cAMP. Among them, the derivative 15 showed a high in vitro potency with desirable pharmacokinetic profile (safe genotoxicity and blood brain barrier penetration). Administration of ITDZ 15 in an experimental autoimmune encephalomyelitis (EAE) mouse model results in a significant attenuation of clinical symptoms, showing the potential of ITDZs, especially compound 15, for the effective treatment of multiple sclerosis.

Proapoptotic effects of novel pentabromobenzylisothioureas in human leukemia cell lines

A series of new pentabromobenzylisothioureas [ZKK-1-ZKK-5; (ZKKs)] carrying additional substituents on nitrogen atoms has been synthesized. The ZKKs were found to induce apoptosis in HL-60 (human promyleocytic leukemia) and K-562 (human chronic erythromyeloblastoid leukemia) cell lines in a concentration-dependent manner at low micromolar concentrations. ZKK-3 [(N,N'-dimethyl-S-2,3,4,5,6-pentabromobenzyl)isothiouronium bromide] showed the highest proapoptotic activity in HL-60 cells, whereas ZKK-2 [N-methyl-S-(2,3,4,5,6-pentabromobenzyl)isothiouronium bromide] was most effective in this respect in K-562 cells. During the ZKKs-induced apoptosis, an 85 kDa fragment of cleaved PARP (caspase-3 and caspase-7 substrate) was detected in both cell lines tested. The studied compounds also decreased mitochondrial transmembrane potential in both these cell lines and caused the cells to accumulate in G(1) and at the G(1)/S border of the cell cycle in a concentration-dependent manner. These results show promise for their study as new compounds in the treatment of leukemia, after an appropriate preclinical toxicity profile.

Proapoptotic effects of novel pentabromobenzylisothioureas in human leukemia cell lines

A series of new pentabromobenzylisothioureas [ZKK-1–ZKK-5; (ZKKs)] carrying additional substituents on nitrogen atoms has been synthesized. The ZKKs were found to induce apoptosis in HL-60 (human promyleocytic leukemia) and K-562 (human chronic erythromyeloblastoid leukemia) cell lines in a concentration-dependent manner at low micromolar concentrations. ZKK-3 [(N,N′-dimethyl-S-2,3,4,5,6-pentabromobenzyl)isothiouronium bromide] showed the highest proapoptotic activity in HL-60 cells, whereas ZKK-2 [N-methyl-S-(2,3,4,5,6-pentabromobenzyl)isothiouronium bromide] was most effective in this respect in K-562 cells. During the ZKKs-induced apoptosis, an 85 kDa fragment of cleaved PARP (caspase-3 and caspase-7 substrate) was detected in both cell lines tested. The studied compounds also decreased mitochondrial transmembrane potential in both these cell lines and caused the cells to accumulate in G₁ and at the G₁/S border of the cell cycle in a concentration-dependent manner. These results show promise for their study as new compounds in the treatment of leukemia, after an appropriate preclinical toxicity profile.