2,4,5-Trisubstituted Thiazole: A Privileged Scaffold in Drug Design and Activity Improvement.

Thiazole is an important 5-membered heterocyclic compound containing nitrogen and sulfur atoms with various pharmaceutical applications including anti-inflammatory, anti-cancer, anti-viral, hypoglycemic, anti-bacterial and anti-fungal activities. Until now, the FDA-approved drugs containing thiazole moiety have achieved great success such as dasatinib and dabrafenib. In recent years, considerable research has been focused on thiazole derivatives, especially 2,4,5-trisubstituted thiazole derivatives, due to their multiple medicinal applications. This review covers related literature in the past 20 years, which reported the 2,4,5-trisubstituted thiazole as a privileged scaffold in drug design and activity improvement. Moreover, this review aimed to provide greater insights into the rational design of more potent pharmaceutical molecules based on 2,4,5-trisubstituted thiazole in the future.

Sarcodonin G Derivatives Exhibit Distinctive Effects on Neurite Outgrowth by Modulating NGF Signaling in PC12 Cells.

Sarcodonin G, one of the cyathane diterpenoids isolated from the mushroom Sarcodon scabrosus, possesses pronounced neurotrophic activity but ambiguous mechanical understanding. In this work, sarcodonin G was chosen as a lead compound to prepare a series of 19- O-benzoyl derivatives by semisynthesis and their neuritogenic activities were evaluated. 6 and 15 (10 µM) were investigated with opposite effects in PC12 cells. 6 exhibited a superior activity to sarcodonin G by promoting NGF-induced neurite outgrowth, while 15 showed an inhibitory effect. Supportingly, 6 and 15 (20 µM) significantly induced and suppressed neurite extension in primary cultured rat cortical neurons, respectively. In mechanism, the two derivatives were revealed to influence NGF-induced neurite outgrowth in PC12 cells through the regulation of PKC-dependent and -independent ERK/CREB signaling as well as the upstream TrkA receptor phosphorylation. Furthermore, a possible pattern of interaction among NGF, 6/15 and TrkA was presented using molecular simulations. It revealed that 6/15 may contribute to the stabilization of the NGF-TrkAd5 complex by establishing several hydrophobic and hydrogen-bond interactions with NGF and TrkA, respectively. Taken together, 6 and 15 modulate PKC-dependent and -independent ERK/CREB signaling pathways possibly by influencing the binding affinity of NGF to the receptor TrkA, and finally regulate neurite outgrowth in PC12 cells.

Synthetic Approaches to the New Drugs Approved During 2015.

New drugs introduced to the market every year represent privileged structures for particular biological targets. These new chemical entities (NCEs) provide insight into molecular recognition while serving as leads for designing future new drugs. This annual review describes the most likely process-scale synthetic approaches to 29 new chemical entities (NCEs) that were approved for the first time in 2015.

1,8-Naphthyridine Derivatives: A Review of Multiple Biological Activities.

The 1,8-naphthyridine group of compounds have gained special attention of researchers on account of their demonstrating a variety of interesting biological activities. A wide range of biological properties establishes them as potent scaffolds in therapeutic and medicinal research. The broad spectrum of activities primarily includes antimicrobial, antiviral, anticancer, anti-inflammatory, and analgesic activities. 1,8-Naphthyridine derivatives have also exhibited potential applications in neurological disorders such as Alzheimer's disease, multiple sclerosis, and depression. In addition, these synthetic derivatives have been found to possess activities such as anti-osteoporotic (α(v)ß(3) antagonists), anti-allergic, antimalarial, gastric antisecretory, bronchodilator, anticonvulsant, anti-hypertensive, platelet aggregation inhibition, anti-oxidant, EGFR inhibition, protein kinase inhibition, ionotropic agent, ß-3 antagonist, MDR modulator, adenosine receptor agonist, adrenoceptor antagonist, and pesticide activities. In spite of the widespread application of the 1,8-naphythyridine scaffolds, only a limited number of review articles are available till date. In this review, we attempt to compile and discuss the key data available in the literature for the multiple biological activities of 1,8-naphthyridine derivatives, in a chronological manner. This review compilation (with 199 references) may be helpful in understanding the diverse biological properties of 1,8-naphthyridines and provide insights into their mechanism of action. This may direct future research in the synthesis of new derivatives and exploring this scaffold for other possible biological activities.

Iron catalysed cross-couplings of azetidines - application to the formal synthesis of a pharmacologically active molecule.

A protocol for the coupling of 3-iodoazetidines with Grignard reagents in the presence of an iron catalyst has been developed. A variety of aryl, heteroaryl, vinyl and alkyl Grignards were shown to participate in the coupling process to give the products in good to excellent yields. Furthermore, a short formal synthesis towards a pharmacologically active molecule was shown.

CNS and antimalarial activity of synthetic meridianin and psammopemmin analogs.

The marine invertebrate-derived meridianin A, the originally proposed structure for psammopemmin A, and several related 3-pyrimidylindole analogs were synthesized and subsequently investigated for central nervous system, antimalarial, and cytotoxic activity. A Suzuki coupling of an indoleborate ester to the pyrimidine electrophile was utilized to form the natural product and derivatives thereof. The 3-pyrimidineindoles were found to prevent radioligand binding to several CNS receptors and transporters, most notably, serotonin receptors (<0.2 µM K(i) for 5HT(2B)). Two compounds also inhibited the human malaria parasite Plasmodium falciparum (IC(50) <50 µM). Only the natural product was cytotoxic toward A549 cells (IC(50)=15 µM).

Tricyclic thiazolopyrazole derivatives as metabotropic glutamate receptor 4 positive allosteric modulators.

There is an increasing amount of evidence to support that activation of the metabotropic glutamate receptor 4 (mGlu4 receptor), either with an orthosteric agonist or a positive allosteric modulator (PAM), provides impactful interventions in diseases such as Parkinson's disease, anxiety, and pain. mGlu4 PAMs may have several advantages over mGlu4 agonists for a number of reasons. As part of our efforts in identifying therapeutics for central nervous system (CNS) diseases such as Parkinson's disease, we have been focusing on metabotropic glutamate receptors. Herein we report our studies with a series of tricyclic thiazolopyrazoles as mGlu4 PAMs.

Switching reversibility to irreversibility in glycogen synthase kinase 3 inhibitors: clues for specific design of new compounds.

Development of kinase-targeted therapies for central nervous system (CNS) diseases is a great challenge. Glycogen synthase kinase 3 (GSK-3) offers a great potential for severe CNS unmet diseases, being one of the inhibitors on clinical trials for different tauopathies. Following our hypothesis based on the enhanced reactivity of residue Cys199 in the binding site of GSK-3, we examine here the suitability of phenylhalomethylketones as irreversible inhibitors. Our data confirm that the halomethylketone unit is essential for the inhibitory activity. Moreover, addition of the halomethylketone moiety to reversible inhibitors turned them into irreversible inhibitors with IC(50) values in the nanomolar range. Overall, the results point out that these compounds might be useful pharmacological tools to explore physiological and pathological processes related to signaling pathways regulated by GSK-3 opening new avenues for the discovery of novel GSK-3 inhibitors.

[TDAE strategy applied to drug-candidate synthesis]. / Stratégie TDAE appliquée à la synthèse de candidats-médicaments.

Research, developed at the Laboratory of Organic Pharmaceutical Chemistry of the School of Pharmacy, UMR-CNRS 6517, is centred on the synthesis of novel therapeutic compounds using monoelectronic transfer reactions. Tetrakis(dimethylamino)ethylene (TDAE) is a powerful electron donor which has the specific property of activating the carbon-halogen bond leading to the formation of a stable electrophilic radical and a stable neutrophilic anion. Since 2002, our team has developed a program using monoelectronic transfer reactions initiated by TDAE of nitroaromatic, nitroheterocyclic and quinonic bioreducible alkylating agents. The goal is to synthesize new therapeutic compounds for use as anti-infectious agents, anticancer agents, and agents active on the central nervous system. In this context, we present the first pharmacochemical tools obtained with this strategy during reactions between diverse electrophilic compounds (aldehydes, ketones, alpha-keto-esters, ketomalonates, alpha-ketolactames, ...) and benzylic anions formed in situ by the action of TDAE. We illustrate the usefulness of this strategy by describing the preparation of new compounds of biological interest and the associated pharmacomodulation work.

Recent developments in the chemistry and in the biological applications of amidoximes.

Amidoximes are compounds bearing both a hydroxyimino and an amino group at the same carbon atom which makes them versatile building blocks for the synthesis of various heterocycles. Their importance in chemistry along with their rich biology, make amidoximes an attractive target for medicinal chemists, biochemists and biologists. Amidoximes and simple O-substituted derivatives possess very important biological activities functioning as antituberculotic, antibacterial, bacteriostatic, insecticidal, elminthicidal, antiviral, herbicidal, fungicidal, antineoplastic, antiarrythmic, antihypertensive, antihistaminic, anxiolytic-antidepressant, anti-inflammatory/antioxidant, antiaggregatory (NO donors) or plant growth regulatory agents. A number of amidoximes has already been used as drugs, or currently being in clinical trials. Their numerous pharmaceutical applications have been recently enriched, due to the fact that some mechanistic pathways, concerning their conversion to amidines, as well as their ability to release NO were clarified, giving a new insight to their mode of action and allowing the design of new therapeutic agents. The main subject of the present review paper is to highlight aspects concerning chemical and biological questions on this interesting class of compounds. Some new synthetic methodologies as well as improvements of previously reported general reactions involving amidoximes, acylated amidoximes, and amidines are presented. The biological applications of amidoximes over the end of 2006 are also extensively reviewed.

Synthesis and pharmacological activity of urea and thiourea derivatives of 4-azatricyclo[5.2.2.0(2,6)]undec-8-ene-3,5-dione.

A series of nineteen new thiourea and urea derivatives of 10-isopropyl-8-methyl-4-azatricyclo[5.2.2.0(2,6)]undec-8-ene-3,5-dione, 1-isopropyl-7-methyl-4-azatricyclo[5.2.2.0(2,6)]undec-8-ene-3,5-dione and 1,7,8,9,10-pentamethyl-4-azatricyclo[5.2.1.0(2,6)]dec-8-ene-3,5-dione have been prepared and studied by (1)H-NMR. The compound k1a (1-(1,7,8,9,10-pentamethyl-3,5-dioxo-4-aza-tricyclo[5.2.1.0(2,6)]dec-8-en-4-yl)-3-phenyl-urea) was tested for pharmacological activity on animal central nervous system (CNS). The activities of synthesized compounds were evaluated for their cytotoxicity and anti-HIV-1 activity in MT-4 cells. Antimicrobial activity of the newly obtained derivatives was tested against some Gram-positive and Gram-negative bacteria and fungi of the Candida species.

Synthesis of some pyrrolo[3,4-d]pyridazinones and their preliminary anticancer, antimycobacterial and CNS screening.

Starting from 1-substituted-2,5-dimethyl-3,4-pyrroledicarboxylic acid anhydrides 1 and N-methylhydrazine, 1,2,3,4-tetrahydro-6-substituted-2,5,7-trimethyl-6H-pyrrolo[3,4-d]pyridazin- 1,4-ones 2 were prepared. Reaction of compounds 2 with alkylating agents give 3-N- or 4-O-alkylated products 3, 4 or mixtures of these isomers in ratios depending on the alkylating agents. Under preliminary pharmacological screening two of four new pyrrolo[3,4-d]pyridazinones were active as cystostatic agents, all the eight compounds displayed moderate activity against Mycobacterium tuberculosis and two compounds were active as CNS-depressive agents.

Chemistry and biological activity of a tryptamine and beta-carboline series of bases.

Twenty-six derivatives of harmaline and tetrahydroharmine were prepared and characterized by UV, IR, MS, and NMR spectroscopy. They were tested for their antimicrobial, antiplatelet aggregation and cytotoxic activity. Their effect on central nervous system was also studied.

Synthesis and CNS activities of pyridopyrazinone and pyridodiazepinone derivatives.

New tricyclic derivatives with cyclocondensed pyrido-pyrazine 7,10 and pyrido-diazepine 20a,20b skeletons were synthetized and biologically investigated. The compounds, preliminarily tested on explorative, muscle relaxing, antinociceptive, spontaneous motor activities and influence on the narcotic effect of Evipan, revealed interesting CNS depressant and analgesic activities. The pyrido[2,3-e]pyrrolo[1,2-a]pyrazine structure of 7 appeared the most promising for analgesic and neuroleptic activities. The above compounds were assayed also for their capacity to inhibit DNA synthesis in Ehrlich ascites tumor cells; 20a appeared to be able of inducing a significant inhibition.

Thiolupinine and some derivatives of pharmacological interest.

The (quinolizidin-1 alpha-yl)methanthiol (thiolupinine) was prepared and, utilizing the thiol group reactivity, several S-substituted derivatives were obtained among which was a group of 3-[(lupinylthio)methyl]indoles. Eight of the prepared compounds were subjected to a broad pharmacological screening that evidentiated for many of them good level of the following activities in vivo and in vitro: antiarrhythmic, local anesthetic, negative chronotropic on isolated atria, calcium antagonism on ileum and atria, inhibition of spontaneous contraction of isolated trachea, inhibition of guinea pig ileum contractions induced by angiotensin I and II, bradykinin and cholecystokinin, inhibition of platelet aggregation induced by PAF and ADP. Single compounds were remarkable for additional antagonistic activities: 4 against P1-purine receptor, 8 against substance P, 12 against methacholine and 13 strongly inhibited arachidonate induced platelet aggregation. Very peculiar was the ability of compound 6 to protect mice from PAF induced mortality.

Synthesis and CNS activity of some new substituted indeno [1,2-c] pyrazoles.

Some new 1-(6'-substituted-4'-methylquinol-2'-yl)-3-methyl-indeno[1,2- c]pyrazoles (Va-d) have been synthesized by the condensation of 2-acetylindane-1,3-dione (I) with 2-hydrazino-4-methyl-6-substituted quinolines (IIa-d), followed by cyclodehydration with polyphosphoric acid and Wolff-Kishner reduction. Compounds (IVa-d) showed noticeable CNS activity.