Design, synthesis and in vitro biological evaluation of a novel class of anti-adenovirus agents based on 3-amino-1,2-propanediol.

Nowadays there is not an effective drug for the treatment of infections caused by human adenovirus (HAdV) which supposes a clinical challenge, especially for paediatric and immunosuppressed patients. Here, we describe the design, synthesis and biological evaluation as anti-adenovirus agents of a new library (57 compounds) of diester, monoester and triazole derivatives based on 3-amino-1,2-propanediol skeleton. Seven compounds (17, 20, 26, 34, 44, 60 and 66) were selected based on their high anti-HAdV activity at low micromolar concentration (IC50 from 2.47 to 5.75 µM) and low cytotoxicity (CC50 from 28.70 to >200 µM). In addition, our mechanistic assays revealed that compounds 20 and 44 might be targeting specifically the HAdV DNA replication process, and compound 66 would be targeting HAdV E1A mRNA transcription. For compounds 17, 20, 34 and 60, the mechanism of action seems to be associated with later steps after HAdV DNA replication.

Rational Alteration of Pharmacokinetics of Chiral Fluorinated and Deuterated Derivatives of Emixustat for Retinal Therapy.

Recycling of all-trans-retinal to 11-cis-retinal through the visual cycle is a fundamental metabolic pathway in the eye. A potent retinoid isomerase (RPE65) inhibitor, (R)-emixustat, has been developed and tested in several clinical trials; however, it has not received regulatory approval for use in any specific retinopathy. Rapid clearance of this drug presents challenges to maintaining concentrations in eyes within a therapeutic window. To address this pharmacokinetic inadequacy, we rationally designed and synthesized a series of emixustat derivatives with strategically placed fluorine and deuterium atoms to slow down the key metabolic transformations known for emixustat. Crystal structures and quantum chemical analysis of RPE65 in complex with the most potent emixustat derivatives revealed the structural and electronic bases for how fluoro substituents can be favorably accommodated within the active site pocket of RPE65. We found a close (∼3.0 Å) F-π interaction that is predicted to contribute ∼2.4 kcal/mol to the overall binding energy.

Synthesis of erythro- B13 enantiomers and stereospecific action of full set of B13-isomers in MCF7 breast carcinoma cells: Cellular metabolism and effects on sphingolipids.

B13 is an acid ceramidase (ACDase) inhibitor. The two chiral centers of this aromatic amido alcohol lead to four stereoisomers, yet we have little knowledge about its erythro- enantiomers, (1R, 2S) and (1S, 2R). In this paper, for the first time, the synthesis of two erythro- enantiomers is described, and the compounds are evaluated along with two threo- enantiomers, (1R, 2R) and (1S, 2S). The key metabolites and sphingolipid (SL) profile of the full set of B13 stereoisomers in MCF7 breast carcinoma cells are presented. The results demonstrated that the erythro- enantiomers were more effective than the threo- enantiomers on growth inhibition in MCF7 cells, although there were no statistically significant differences within the threo- and erythro- series. Measurement of intracellular levels of the compounds indicated that the erythro- seemed a little more cell permeable than the threo- enantiomers; also, the (1R, 2S) isomer with the same stereo structure as natural ceramide (Cer) could be hydrolyzed and phosphorylated in MCF7 cells. Furthermore, we also observed the formation of C16 homologs from the full set of B13 isomers within the cells, indicating the occurrence of de-acylation and re-acylation of the amino group of the aromatic alcohol. Moreover, the decrease in the Cer/Sph ratio suggests that the growth inhibition from (1R, 2S) isomer is not because of the inhibition of ceramidases. Taken together, (1R, 2S) could be developed as a substitute of natural Cer.

Development of chiral fluorinated alkyl derivatives of emixustat as drug candidates for the treatment of retinal degenerative diseases.

The discovery of how a photon is converted into a chemical signal is one of the most important achievements in the field of vision. A key molecule in this process is the visual chromophore retinal. Several eye diseases are attributed to the abnormal metabolism of retinal in the retina and the retinal pigment epithelium. Also, the accumulation of two toxic retinal derivatives, N-retinylidene-N-retinylethanolamine and the retinal dimer, can damage the retina leading to blindness. RPE65 (Retinal pigment epithelium-specific 65 kDa protein) is one of the central enzymes that regulates the metabolism of retinal and the formation of its toxic metabolites. Its inhibition might decrease the rate of the retina's degeneration by limiting the amount of retinal and its toxic byproducts. Two RPE65 inhibitors, (R)-emixustat and (R)-MB001, were recently developed for this purpose.

Novel propanolamine derivatives attached to 2-metoxifenol moiety: Synthesis, characterization, biological properties, and molecular docking studies.

The synthesis of seven new ß-amino alcohols was designed and performed by starting from eugenol, a natural phenolic compound known to be biologically active. The synthesized compounds were obtained in yields ranging from 54 to 81%. Molecule structures were determined with FT-IR, 1H NMR and 13C NMR spectroscopies. In addition, the inhibitory effects of these substances on acetylcholinesterase (AChE), α-glycosidase (α-Gly), human carbonic anhydrase I (hCA I), and human carbonic anhydrase II (hCA II) enzymes have been investigated. It has been seen that all compounds have a better ability to inhibit compared to existing tried inhibitors. Among these, the best inhibitor against AChE enzyme is 2b (Ki 62.08 ± 11.67 µM and IC50 90.33), and against α-Gly, 2c showed the highest effect (Ki 0.33 ± 0.08 µM and IC50 0.28). The best inhibitor against hCA I, and hCA II enzymes is compound 2f. For hCA I and hCA II, Ki value was measured as 9.68 ± 1.32 and 11.46 ± 2.64 µM and IC50 values as 7.37 and 8.26 µM respectively. The interactions of the studied new propanolamine derivatives with the enzymes were done by molecular docking calculations and their biological activities were compared to the experimental tests. Studied enzymes in molecular docking calculations are acetylcholinesterase (AChE) is PDB ID: 4M0E, α-glycosidase (α-Gly) is PDB ID: 1R47, human carbonic anhydrase isoenzyme I (hCA I) PDB ID: 3LXE is human carbonic anhydrase isoenzyme II (hCA II) is PDB ID: 5 AML.

Arylaminopropanone Derivatives as Potential Cholinesterase Inhibitors: Synthesis, Docking Study and Biological Evaluation.

Neurodegenerative diseases in which the decrease of the acetylcholine is observed are growing worldwide. In the present study, a series of new arylaminopropanone derivatives with N-phenylcarbamate moiety (1-16) were prepared as potential acetylcholinesterase and butyrylcholinesterase inhibitors. In vitro enzyme assays were performed; the results are expressed as a percentage of inhibition and the IC50 values. The inhibitory activities were compared with reference drugs galantamine and rivastigmine showing piperidine derivatives (1-3) as the most potent. A possible mechanism of action for these compounds was determined from a molecular modelling study by using combined techniques of docking, molecular dynamics simulations and quantum mechanics calculations.

Asymmetric Total Synthesis Enables Discovery of Antibacterial Activity of Siladenoserinols A and H.

Siladenoserinols A and H were found to show moderate inhibitory activity toward p53-Hdm2 interactions. Our total synthesis allowed us to further examine their bioactivities, which revealed that (i) siladenoserinols A and H were not cytotoxic against cancer cell lines and (ii) siladenoserinol A and its desulfamate analogue exhibited significant antibacterial activity against Gram-positive bacteria including MRSA. Our studies demonstrate that siladenoserinols are a promising new class of bactericidal Gram-positive antibiotics without hemolytic activity.

Novel eugenol bearing oxypropanolamines: Synthesis, characterization, antibacterial, antidiabetic, and anticholinergic potentials.

Five oxypropanol amine derivatives that four of them are novel have been synthesized with high yields and practical methods. in vitro antibacterial susceptibility of Acinetobacter baumannii, Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus strains to synthesized substances were evaluated with agar well-diffusion method by comparison with commercially available drugs. Most of the bacteria were multidrug resistant. It was concluded that these compounds are much more effective than reference drugs. These eugenol bearing oxypropanolamine derivatives were also effective inhibitors against α-glycosidase, cytosolic carbonic anhydrase I and II isoforms (hCA I and II), and acetylcholinesterase (AChE) enzymes with Ki values in the range of 0.80 ±â€¯0.24-3.52 ±â€¯1.01 µM for hCA I, 1.08 ±â€¯0.15-3.64 ±â€¯0.92 µM for hCA II, 5.18 ±â€¯0.84-12.46 ±â€¯2.08 µM for α-glycosidase, and 11.33 ±â€¯2.83-32.81 ±â€¯9.73 µM for AChE, respectively.

Discovery of novel small molecule TLR4 inhibitors as potent anti-inflammatory agents.

Toll-like receptor 4 (TLR4) initiates innate immune response to release inflammatory cytokines and has been pathologically linked to variety of inflammatory diseases. Recently, we found that Carvedilol, as the classic anti-heart failure and anti-inflammatory clinic drug, could inhibit the TLR4 signaling in the TLR4 overexpressed cells. Herein, we have designed and synthesized a small library of novel Carvedilol derivatives and investigated their potential inhibitory activity. The results indicate that the most potent compound 8a (SMU-XY3) could effectively inhibited TLR4 protein and the LPS triggered alkaline phosphatase signaling in HEK-Blue hTLR4 cells. It down regulated the nitric oxide (NO) in both RAW264.7 cells and BV-2 microglial cells, in addition to blocking the TNF-α signaling in ex-vivo human peripheral blood mononuclear cells (PBMC). More interestingly, 8a shows higher affinity to hyperpolarization-activated cyclic nucleotide-gated 4 (HCN4) over HCN2, which probably indicates the new application of TLR4 inhibitor 8a in heart failure, coronary heart disease, and other inflammatory diseases.

Anesthetic Drug Discovery and Development: A Case Study of Novel Etomidate Analogs.

All currently available general anesthetic agents possess potentially lethal side effects requiring their administration by highly trained clinicians. Among these agents is etomidate, a highly potent imidazole-based intravenous sedative-hypnotic that deleteriously suppresses the synthesis of adrenocortical steroids in a manner that is both potent and persistent. We developed two distinct strategies to design etomidate analogs that retain etomidate's potent hypnotic activity, but produce less adrenocortical suppression than etomidate. One strategy seeks to reduce binding to 11ß-hydroxylase, a critical enzyme in the steroid biosynthetic pathway, which is potently inhibited by etomidate. The other strategy seeks to reduce the duration of adrenocortical suppression after etomidate administration by modifying the drug's structure to render it susceptible to rapid metabolism by esterases. In this chapter, we describe the methods used to evaluate the hypnotic and adrenocortical inhibitory potencies of two lead compounds designed using the aforementioned strategies. Our purpose is to provide a case study for the development of novel analogs of existing drugs with reduced side effects.

Total Synthesis and Biological Evaluation of Siladenoserinol†A and its Analogues.

The total synthesis of siladenoserinol A, an inhibitor of the p53-Hdm2 interaction, has been achieved. AuCl3 -catalyzed hydroalkoxylation of an alkynoate derivative smoothly and regioselectively proceeded to afford a bicycloketal in excellent yield. A glycerophosphocholine moiety was successfully introduced through the Horner-Wadsworth-Emmons reaction using an originally developed phosphonoacetate derivative. Finally, removal of the acid-labile protecting groups, followed by regioselective sulfamate formation of the serinol moiety afforded the desired siladenoserinol A, and benzoyl and desulfamated analogues were also successfully synthesized. Biological evaluation showed that the sulfamate is essential for biological activity, and modification of the acyl group on the bicycloketal can improve the inhibitory activity against the p53-Hdm2 interaction.

Design and synthesis of aryloxypropanolamine as ß3-adrenergic receptor antagonist in cancer and lipolysis.

ß-adrenergic receptors (ß-ARs) are broadly distributed in various tissues and regulate a panel of important physiological functions and disease states including cancer. Above all, ß3-adrenergic receptor (ß3-AR) plays a significant role in regulating lipolysis and thermogenesis in adipose tissue. In this study, we designed and synthesized a series of novel L-748,337 derivatives as selective human ß3-AR antagonists. Among all the tested L-748,337 analogs, compound 23d was found to display 23-fold more potent ß3-AR antagonist activity (EC50 = 0.5117 nM) than L-748,337 (EC50 = 11.91 nM). In vivo, compound 23d could alleviate weight loss and inhibit tumor growth in C26 tumor cachexia animal model.

Radioiodinated esmolol as a highly selective radiotracer for myocardial perfusion imaging: In silico study and preclinical evaluation.

Challenges facing cardiovascular imaging necessitate innovation of better radiopharmaceuticals to augment or replace the existing ones. This research assesses the ability and competency of radioiodinated esmolol as a potential cardio selective imaging agent. Radioiodinated esmolol was synthesized with 97.3 ±â€¯0.3% radiochemical yield and with high stability up to 48 h at room temperature as well as in rat serum. Molecular modeling study was performed to confirm the binding of iodinated esmolol to ß1-adrenergic receptor. Its biodistribution studies in normal Swiss albino mice showed high heart uptake (38.5 ±â€¯0.11%ID/g at 5 min p.i.), heart/liver ratio nearly 3.85:1 and heart/lungs ratio was about 7:1 at 5 min p.i. The evidenced selectivity of the radioiodinated esmolol to ß1-adrenoceptor was confirmed by prior injection of cold esmolol. Gamma camera biodistribution pattern showed that radioiodinated esmolol accumulated selectively in heart.

Design, synthesis and evaluation of 1,4-benzodioxine derivatives as novel platelet aggregation inhibitors.

AIM: To find novel platelet aggregation inhibitors, two new series of 1,4-benzodioxine derivatives were synthesized and screened for the ability to inhibit platelet aggregation. MATERIALS & METHODS: The synthesized compounds were evaluated for antiplatelet aggregation activity using human blood platelet and GPIIb/IIIa antagonistic activity. RESULTS: Compound 9-2p showed significant antiplatelet activity with the IC50 values of 41.7 and 22.2 µM induced by ADP and thrombin, respectively, more potent than that of LX2421. Compound 9-2p exhibited GPIIb/IIIa antagonistic activity with the IC50 value of 2.3 µM, as potent as RGDs. In vivo study showed that 9-2p displayed remarkable antithrombotic activity, more effective than LX2421, but less effective than tirofiban. CONCLUSION: Compound 9-2p showed moderate antiplatelet activity and antithrombotic activity, which could be further optimized based on the target of GPIIb/IIIa.

Novel hybrids of natural ß-elemene bearing isopropanolamine moieties: Synthesis, enhanced anticancer profile, and improved aqueous solubility.

A series of novel ß-elemene isopropanolamine derivatives were synthesized and evaluated for their antitumor activity. The results indicated that all of the compounds showed stronger antiproliferative activities than ß-elemene as well as improved aqueous solubility. In particular dimer 6q showed the strongest cytotoxicity against four tumor cell lines (SGC-7901, HeLa, U87 and A549) with IC50 values ranging from 4.37 to 10.20µM. Moreover, combination of 6q with cisplatin exhibited a synergistic effect on these cell lines with IC50 values ranging from 1.21 to 2.94µM, and reversed the resistance of A549/DPP cells with an IC50 value of 2.52µM. The mechanism study revealed that 6q caused cell cycle arrest at the G2 phase and induced apoptosis of SGC-7901 cells through a mitochondrial-dependent apoptotic pathway. Further in vivo study in H22 liver cancer xenograft mouse model validated the antitumor activity of 6q with a tumor inhibitory ratio (TIR) of 60.3%, which was higher than that of ß-elemene (TIR, 49.1%) at a dose of 60mg/kg. Altogether, the potent antitumor activity of 6qin vitro and in vivo warranted further preclinical investigation for potential anticancer chemotherapy.

Synthesis of Glycoborine, Glybomine A and B, the Phytoalexin Carbalexin A and the ß-Adrenoreceptor Antagonists Carazolol and Carvedilol.

We describe a regioselective synthesis of 4- or 5-substituted carbazoles by oxidative cyclisation of meta-oxygen-substituted N-phenylanilines. Using the regiodirecting effect of a pivaloyloxy group, we prepared 4-hydroxycarbazole, a precursor for the enantiospecific synthesis of the ß-adrenoreceptor antagonists (-)-(S)-carazolol (5) and (-)-(S)-carvedilol (6). Regioselective palladium(II)-catalysed cyclisation of different diarylamines led to total synthesis of glycoborine (7) and the first total syntheses of the phytoalexin carbalexin A (8), glybomine A (9) and glybomine B (10). For glybomine B (10), a 5-hydroxycarbazole was converted into the corresponding triflate and utilized for introduction of a prenyl substituent.

Synthesis and In Vitro Pharmacological Evaluation of 5-(Alkoxymethyl)-2-(3-alkylamino-2-hydroxypropoxy)phenylethanones Related to Acebutolol and Celiprolol.

The structure-activity relationships of 13 analogs of aryloxyaminopropanol type derived from 2-hydroxyphenylethanone as potential ß-blockers are described. The synthesized compounds possess an isopropyl or a tert-butyl group in the hydrophilic part of the molecule and an alkoxymethyl substitution in the lipophilic moiety. The target compounds were prepared by an established four-step method and their structures were confirmed by interpretation of their UV, IR, (1) H NMR and (13) C NMR spectra, and by elemental analysis. The ß-adrenolytic efficacy of the prepared racemic compounds was determined on isolated guinea pig atria (ß1 ) and trachea (ß2 ) and expressed as pA2 values against isoprenaline tachycardia. The assumed cardioselectivity was expressed as ß1 /ß2 ratio and the values of compounds with an alkoxy group (CH3 O, iC3 H5 O, C5 H11 O, CH2 CHCH2 O, CH3 OCH2 CH2 O) in the lipophilic part and with tert-butyl in the hydrophilic part of the molecule were found to be comparable or higher than those of the standards acebutolol and celiprolol. All evaluated substances at a concentration of 10(-7) mol/dm(3) showed also negative chronotropic effects.

Part 2. Notch-sparing γ-secretase inhibitors: The study of novel γ-amino naphthyl alcohols.

One therapeutic approach for Alzheimer's disease is to inhibit the cleavage of the amyloid precursor protein (APP) by γ-secretase. At the beginning of a series of studies from our laboratories, a series of novel γ-amino alcohols (1) were found to possess γ-secretase inhibitory activity and Notch-sparing effects. A new one-pot synthesis of γ-amino alcohols and the structure-activity relationship (SAR) of these analogs will be discussed.

The influence of the polar head-group of synthetic cationic lipids on the transfection efficiency mediated by niosomes in rat retina and brain.

The development of novel non-viral delivery vehicles is essential in the search of more efficient strategies for retina and brain diseases. Herein, optimized niosome formulations prepared by oil-in water (o/w) and film-hydration techniques were characterized in terms of size, PDI, zeta potential, morphology and stability. Three ionizable glycerol-based cationic lipids containing a primary amine group (lipid 1), a triglycine group (lipid 2) and a dimethylamino ethyl pendent group (lipid 3) as polar head-groups were part of such niosomes. Upon the addition of pCMS-EGFP plasmid, nioplexes were obtained at different cationic lipid/DNA ratios (w/w). The resultant nioplexes were further physicochemically characterized and evaluated to condense, release and protect the DNA against enzymatic digestion. In vitro experiments were performed to evaluate transfection efficiency and cell viability in HEK-293, ARPE-19 and PECC cells. Interestingly, niosome formulations based on lipid 3 showed better transfection efficiencies in ARPE-19 and PECC cells than the rest of cationic lipids showed in this study. In vivo experiments in rat retina after intravitreal and subretinal injections together with in rat brain after cerebral cortex administration showed promising transfection efficiencies when niosome formulations based on lipid 3 were used. These results provide new insights for the development of non-viral vectors based on cationic lipids and their applications for efficient delivery of genetic material to the retina and brain.

Catalytic mechanism of a retinoid isomerase essential for vertebrate vision.

Visual function in vertebrates is dependent on the membrane-bound retinoid isomerase RPE65, an essential component of the retinoid cycle pathway that regenerates 11-cis-retinal for rod and cone opsins. The mechanism by which RPE65 catalyzes stereoselective retinoid isomerization has remained elusive because of uncertainty about how retinoids bind to its active site. Here we present crystal structures of RPE65 in complex with retinoid-mimetic compounds, one of which is in clinical trials for the treatment of age-related macular degeneration. The structures reveal the active site retinoid-binding cavity located near the membrane-interacting surface of the enzyme as well as an Fe-bound palmitate ligand positioned in an adjacent pocket. With the geometry of the RPE65-substrate complex clarified, we delineate a mechanism of catalysis that reconciles the extensive biochemical and structural research on this enzyme. These data provide molecular foundations for understanding a key process in vision and pharmacological inhibition of RPE65 with small molecules.