H2-receptor antagonist activity of N-methylthiourea, N-cyano-N'-methylguanidine, N-cyanoamidine, N-carbamoylamidine and N-sulfamoylamidine 5-substituted thiazole derivatives on guinea-pig atria

The H2-antagonist activity of thiazole derivatives, substituted on position 5 with urea-equivalent groups, has been tested on guinea-pig isolated atria stimulated by dimaprit. By comparing the activities of the 2,5-disubstituted thiazole derivatives with those of the corresponding 2,4-disubstituted derivatives it can be seen that the side-chain position is critical to activity and differently influences activity in the various series. The heteroaromatic ring atom sequence N-C-S-C-side chain is always associated with a low antagonist activity.     

New series of morpholine and 1,4-oxazepane derivatives as dopamine D4 receptor ligands: synthesis and 3D-QSAR model

Since the identification of the dopamine D(4) receptor subtype and speculations about its possible involvement in schizophrenia, much work has been put into development of selective D(4) ligands. These selective ligands may be effective antipsychotics without extrapyramidal side effects. This work describes the synthesis of a new series of 2,4-disubstituted morpholines and 2,4-disubstituted 1,4-oxazepanes with selectivity for the dopamine D(4) receptor. A 3D-QSAR analysis using the GRID/GOLPE methodology was performed with the purpose to get a better understanding of the relationship between chemical structure and biological activity. Inspection of the coefficient plots allowed us to identify that regions which are important for affinity are situated around the two benzene ring systems, a p-chlorobenzyl group, and the aliphatic amine belonging to the morpholine or 1,4-oxazepane system. In addition, the size of the morpholine or 1,4-oxazepane ring seems to be important for affinity.     

SAR and 3D-QSAR studies on thiadiazolidinone derivatives: exploration of structural requirements for glycogen synthase kinase 3 inhibitors

The 2,4-disubstituted thiadiazolidinones (TDZD) are described as the first ATP-noncompetitive GSK-3 inhibitors. Following an SAR study about TDZD, different structural modifications in the heterocyclic ring aimed to test the influence of each heteroatom on the biological study are here reported here. Various compounds such as hydantoins, dithiazolidindiones, rhodanines, maleimides, and triazoles were synthesized and screened as GSK-3 inhibitors. After an extensive SAR study among these different heterocyclic families, TDZDs have been revealed as a privileged scaffold for the selective inhibition of GSK-3. A CoMFA analysis was also performed highlighting the molecular electrostatic field interaction in the interaction of TDZDs with GSK-3. Moreover, first mapping studies indicate two binding modes which in turn might imply relevant differences in the mechanism that underly the inhibitory activity of TDZDs.     

Antibacterials. synthesis and structure-activity studies of 3-aryl-2-oxooxazolidines. 4. Multiply-substituted aryl derivatives.

The synthesis and structure-activity relationship (SAR) studies of the effect of different polysubstitution patterns in the aromatic ring of 5-(acetamidomethyl)oxazolidinone antibacterials (I) on antibacterial activity are presented. Compounds I were prepared by the six-step synthesis described previously (Gregory, W. A.; et al. J. Med. Chem. [formula: see text] 1989, 32, 1673), electrophilic aromatic substitution reactions of 3-substituted compounds, and functional-group interchange reactions of 3,4-disubstituted compounds. Antibacterial evaluation of compounds I against Staphylococcus aureus and Enterococcus faecalis gave the following results. The 2,4- and 2,5-disubstituted derivatives have weak or no antibacterial activity. Antibacterial activities of 3,4-disubstituted compounds are comparable to those of the 4-monosubstituted analogues for small 3-substituents (smaller than Br), but decline rapidly for larger 3-substituents. 3,4-Annulated derivatives are comparable in activity to their open-chain analogues. 3,5-Disubstituted and 3,4,5- and 2,4,6-trisubstituted derivatives are devoid of antibacterial activity.     

Some new thiazolyl thiazolidinedione derivatives as aldose reductase inhibitors

In diabetes, increased flux through the polyol pathway has been implicated in the development of diabetic complications such as cataract, retinopathy, neuropathy, and nephropathy. Aldose reductase (AR) appears to be the key factor in the reduction of glucose to sorbitol. Aldose reductase inhibitors have been found to prevent sorbitol accumulation in tissues. A series of thiazolyl-2,4-thiazolidinediones was prepared by Knoevenagel reaction of substituted benzyl-2,4-thiazolidinediones with chlorothiazolecarbaldehydes and were evaluated for their ability to inhibit rat kidney AR by an in vitro spectrophotometric assay. Results showed that compounds containing piperidine at the C-2 position of thiazole ring showed better inhibitory activity than thiazole compounds having 4-chlorobenzylsulfanyl at the same position.     

Novel 1,2,5-oxadiazine derivatives--synthesis and in vitro biological studies

A new synthetic approach to the 1,2,5-oxadiazine ring system is described. 2-Substituted or 2,4-disubstituted 2H-1,2,5-oxadiazine-3,6(4H,5H)-dione derivatives 4 were prepared by cyclisation of hydroxamic acids 3 derived from N-(1-benzotriazolylcarbonyl)-amino acids 1. The structures of the synthesised compounds were fully characterised by IR, 1H and 13C NMR spectroscopy and elemental analysis. The aim of this study was to evaluate biological activity of the newly synthesised oxadiazine derivatives. Cytotoxic and cytostatic activities were tested on two cell lines (HeLa and GMK) and evaluated by MTT-test. Two human DNA viruses (adenovirus 7 and herpesvirus 1) and two human RNA viruses (coxsackievirus B5 and echovirus 7) were used in the antiviral test. Selected biological studies indicated that 2-phenyl- -2H-1,2,5-oxadiazine-3,6(4H,5H)-dione (4a) and 4-benzyl-2-phenyl-2H-1,2,5-oxadiazine-3,6(4H,5H)-dione (4c) statistically significantly inhibited cell growth. A minor antiviral effect was observed upon adenovirus, herpesvirus and enteroviruses.     

Monoamine oxidase inhibitory effects of pentanthrene type heterocyclic compounds]

Pentanthrene type heterocyclic compounds, which contain oxazole, isoxazole, oxadiazole, thiazole, isothiazole, thiadiazole or pyrrole ring as C-ring, and naphthalene, quinoline, isoquinoline or quinoxaline ring as A.B-ring, were prepared, and their monoamine oxidase (MAO) inhibitory activities were examined. As expected from our previous investigation on the structure-activity relationship of this series, most of them showed strong inhibitory potency to both MAO-A and MAO-B. However, a few indicated highly selective inhibition for either of MAO subtypes.     

Natural resorcylic acid lactones: A chemical biology approach for anticancer activity

Resorcylic acid lactones (RALs) are fungal polyketides that consist of a β-resorcylic acid residue (2,4-dihydroxybenzoic acid) embedded in a macrolactone ring. RALs exhibit a broad range of biological activities, including anticancer activities. Following discovery of the selective Hsp90 inhibition activity of radicicol, the kinase inhibition activity of hypothemycin, monocillin II, 5Z-7-oxo-zeaenol, and L-783,277 RALs, and the nuclear factor kappa B (NF-κB) inhibition activity of the RAL zearalenone, have attracted great attention as potential therapeutics for cancer treatment. In this minireview, we focus on natural RALs that possess cytotoxic activities [IC₅₀ values < 10 μM (or 4–5 μg/ml)], discussing their structures, isolation, occurrence, biological activities, and anticancer molecular mechanisms.     

Heteroatom-substituted analogues of orphan nuclear receptor small heterodimer partner ligand and apoptosis inducer (E)-4-[3-(1-Adamantyl)-4-hydroxyphenyl]-3-chlorocinnamic acid

(E)-4-[3'-(1-Adamantyl)-4'-hydroxyphenyl]-3-chlorocinnamic acid (3-Cl-AHPC) induces the cell cycle arrest and apoptosis of cancer cells. Because its pharmacologic properties-solubility, bioavailability, and toxicity-required improvement for translation, structural modifications were made by introducing nitrogen atoms into the cinnamyl ring and replacing its E-double bond with XCH(2) (X = O, N, and S) with the objective of enhancing these properties without impacting apoptosis-inducing activity. Analogues having nitrogen atoms in heterocyclic rings corresponding to the cinnamyl phenyl ring displayed equal or higher biological activities. The pyrimidine and pyridine analogues were more soluble in both phosphate-buffered saline and water. While the 2,5-disubstituted pyridine analogue was the most potent inducer of KG-1 acute myeloid leukemia cell apoptosis, on the basis of apoptotic activity in KG-1 cells and solubility, the 2,5-disubstituted pyrimidine proved to be the more promising candidate for treatment of acute myeloid leukemia.     

Recent cancer drug development with xanthone structures

Objectives Xanthones are simple three‐membered ring compounds that are mainly found as secondary metabolites in higher plants and microorganisms. Xanthones have very diverse biological profiles, including antihypertensive, antioxidative, antithrombotic and anticancer activity, depending on their diverse structures, which are modified by substituents on the ring system. Although several reviews have already been published on xanthone compounds, few of them have focused on the anticancer activity of xanthone derivatives. In this review we briefly summarize natural and synthetic xanthone compounds which have potential as anticancer drugs. Key findings The interesting structural scaffold and pharmacological importance of xanthone derivatives have led many scientists to isolate or synthesize these compounds as novel drug candidates. In the past, extensive research has been conducted to obtain xanthone derivatives from natural resources as well as through synthetic chemistry. Xanthones interact with various pharmacological targets based on the different substituents on the core ring. The anticancer activities of xanthones are also dramatically altered by the ring substituents and their positions. Summary The biological activities of synthetic xanthone derivatives depend on the various substituents and their position. Study of the biological mechanism of action of xanthone analogues, however, has not been conducted extensively compared to the diversity of xanthone compounds. Elucidation of the exact biological target of xanthone compounds will provide better opportunities for these compounds to be developed as potent anticancer drugs. At the same time, modification of natural xanthone derivatives aimed at specific targets is capable of expanding the biological spectrum of xanthone compounds.     

Studies on histamine H2 receptor antagonists. 2. Synthesis and pharmacological activities of N-sulfamoyl and N-sulfonyl amidine derivatives

A series of N-sulfamoyl and N-sulfonyl amidines have been prepared and tested in vitro for H2 antihistamine activity on guinea pig atrium. In addition, several selected compounds were assessed as inhibitors of gastric acid secretion induced by histamine in anesthetized dogs. Structure-activity relationship studies showed that those compounds containing 2-[(diaminomethylene)amino]thiazole exhibited potent H2-receptor antagonist activity. Introduction of alkyl or aralkyl groups to the terminal nitrogen of the sulfamoyl moiety reduced biological activities. Sulfamoyl amidines were more potent in both tests than sulfonyl amidines. Of these compounds, 3-[[[2-[(diaminomethylene)amino]-4-thiazolyl]methyl]thio]- N2-sulfamoylpropionamidine (2e, famotidine) showed extremely high potency in both assays and was selected for clinical trials as an antiulcer agent. Acid-catalyzed hydrolysis of famotidine gave the sulfamoyl amide 6 at room temperature and the carboxylic acid 7 at elevated temperatures. 15N NMR spectrum showed that famotidine in solution existed in only one of several possible tautomers derived from the amidine and the guanidine moieties. Nitrosation of famotidine was performed under mild condition and proved to occur on the 5-position of the thiazole ring.     

Recent advances in coumarins and 1-azacoumarins as versatile biodynamic agents

Coumarins, also referred as benzopyran-2-ones, and their corresponding nitrogen counterpart, 1-azacoumarins also referred to as carbostyrils, are a family of nature-occurring lactones and lactams respectively. The plant extracts containing coumarin-related heterocycles, which were employed as herbal remedies in early days, have now been extensively studied for their biological activities. These investigations have revealed their potentials as versatile biodynamic agents. For example, coumarins with phenolic hydroxyl groups have the ability to scavenge reactive oxygen species and thus prevent the formation of 5-HETE and HHT in the arachidonic pathway of inflammation suppression. Recent in vivo studies have revealed the role of coumarins in hepatotoxicity and also in depletion of cytochrome P450. Similarly 1-azacoumarins which is part of quinoline alkaloids, are known for their diverse biological activity and recently, a 6-functionalized 1-aza coumarins are undergoing human clinical trials as an orally active anti-tumor drug in view of its farnesyl protein-inhibiting activity in the nanomolar range. Furthermore, several synthetic coumarins with a variety of pharmacophoric groups at C-3, C-4 and C-7 positions have been intensively screened for anti-microbial, anti-HIV, anti-cancer, lipid-lowering, anti-oxidant, and anti-coagulation activities. Specifically, coumarin-3-sulfonamides and carboxamides were reported to exhibit selective cytotoxicity against mammalian cancer cell lines. The C4-substituted aryloxymethyl, arylaminomethyl, and dichloroacetamidomethyl coumarins, along with the corresponding 1-azacoumarins, have been demonstrated to be potential anti-microbial and anti-inflammatory agents. To expand the structural diversity of synthetic courmarins for biological functions, attempts have also been made to attach a chloramphenicol side chain at C-3 position of courmarin. In addition, the bi- and tri-heterocyclic coumarins and 1-azacoumarins with benzofuran, furan and thiazole ring systems along with biocompatible fragments like vanillin have shown remarkable potency as anti-inflammatory agents in animal models. Photobiological studies on pyridine-fused polycyclic coumarins have highlighted their potential as thymine dimer photosensitisers and the structurally related compounds of both coumarin and carbostyrils have also been found to act via the DNA gyrase pathway in their anti-bacterial activity. Apart from the above works, the present review also addresses the potential roles of coumarins and carbostyrils as protease inhibitors, or fluorescent probes in mechanistic investigation of biochemical pathways, and their application for QSAR in theoretical studies. Though 1-Azacoumarins have received less attention as compared to coumarins in the literature, an attempt has been made to compare both the systems at various stages, so that it can spark new thoughts on synthetic methodologies, reactivity pattern and biological activities.     

Studies on antidiabetic agents. 11. Novel thiazolidinedione derivatives as potent hypoglycemic and hypolipidemic agents.

In the course of further chemical modification of the novel antidiabetic pioglitazone (AD-4833, U-72,107), a series of 5-[4-(2- or 4-azolylalkoxy)benzyl- or -benzylidene]-2,4-thiazolidinediones was prepared and evaluated for hypoglycemic and hypolipidemic activities in insulin-resistant, genetically obese, and diabetic KKA(y) mice. Replacement of the 2-pyridyl moiety of pioglitazone by a 2- or 4-oxazolyl or a 2- or 4-thiazolyl moiety greatly enhanced in vivo potency. The corresponding 5-benzylidene-type compounds, in which a methine was used as a linker between the benzene ring and the thiazolidinedione ring, also had potent biological activity. Among the compounds synthesized, 5-[4-[2-(5-methyl-2-phenyl-4-oxazolyl)ethoxy]benzyl]-2,4- thiazolidinedione (18) exhibited the most potent activity, more than 100 times that of pioglitazone. The synthesis and structure-activity relationships for this novel series of derivatives are detailed.     

Synthesis and anti-microbial activity of isothiosemicarbazones and cyclic analogues

It is known that some derivatives of both thiourea and thiosemicarbazide exhibit potent anti-microbial activity. In order to investigate the effects on the biological properties of structural modifications of such structures, we have synthesised and studied some arylidenisothiosemicarbazones. In this paper we report on the synthesis and structure-activity relationships of some isothiosemicarbazones, where the arylidene group has been replaced with a cycloalkyl group and the sulfur atom has been either differently substituted or enclosed in a thiazole ring.     

Synthesis and antidiabetic activity of some new thiazolyl-2,4-thiazolidinediones

In this study, a series of thiazolyl-2,4-thiazolidinediones (VIa-f, VIHa-f and VIIa-f) was prepared by Knoevenagel reaction of substituted phenacyl-2,4-thiazolidinediones (IVa-f)/substituted benzyl-2,4-thiazolidinediones (Va-f) with chlorothiazolecarbaldehydes (II, III).The prepared compounds were tested for their insulinotropic activities in INS-1 cells. A significant insulinotropic effect was seen with compounds VIa, VIb, VIe, VIIa, VIIb and VIIId. Introducing a 2-[(phenylethyl)thio] group into the thiazole ring increased the biological effect, whereas NO2 groups in phenylacyl or benzyl groups diminished the effects.     

Synthesis and anti-HIV activity evaluation of novel 2,4-disubstituted 7-methyl-1,1,3-trioxo-2,4-dihydro-pyrazolo-[4,5-e][1,2]thiadiazines

A series of novel 2,4-disubstituted 7-methyl-1,1,3-trioxo-2,4-dihydro-pyrazolo[4,5-e] [1,2,4]thiadiazines (PTDs) was synthesized, structurally confirmed by spectral analysis, and evaluated for their anti-HIV activities by inhibition of HIV-induced cytopathogenicity in MT-4 cell culture. The results showed that some compounds exhibited inhibitory activity specifically against HIV-2 replication. The most active HIV-2 inhibitor was compound 7i (R1 = benzyl, R2 = 4-t-butyl-benzyl) with an EC50 value of 18.7 microM and SI=15, which may provide a useful lead for further molecular optimization.     

Optically active derivatives of imidazolines. alpha-Adrenergic blocking properties

The synthesis and alpha-adrenergic blocking activity of a series of optically active 2,4-disubstituted imidazolines are presented. The substituted analogues of naphazoline, tolazoline, and clonidine possess moderate alpha-adrenergic blocking activity with -log KB values in the range from 4.77 to 6.57. The differences between the alpha-adrenergic blocking activity of the stereoisomers of the 2,4-disubstituted imidazolines were small or insignificant in the rabbit aortic tissue preparations.     

Relationship between Antifungal Activity against Candida albicans and Electron Parameters of Selected N-Heterocyclic Thioamides

Due to the increasing demand for new pharmaceuticals showing biological activity against pathogenic microorganisms, there is increasing search for new compounds with predicted biological activity. Variously substituted thioamide derivatives with 1.3 and 1.2 ring of thiazole and 1,3,4-thiadiazole, as well as pyrazole were assessed for their activity against Candida albicans. Activity of majority of tested thioamides was larger as compared with that of the reference drugs. The electron parameters of obtained N-heterocyclic thioamides were determined and dependencies on their biological activity against Candida albicans were studied. The best electron compliance of produced bindings with the activity against Candida albicans was observed for the derivatives containing 1,3,4-thiadiazole ring.     

苯并噻唑衍生物抗肿瘤活性研究进展

杂环化合物的生物活性研究一直受到药物化学家的重视。苯并噻唑属于苯环并五元杂环,其衍生物易于合成,已被广泛应用于抗肿瘤尤其是具有分子靶向性抗肿瘤药物的研发。苯并噻唑衍生物可以通过多种途径发挥抗肿瘤作用,如激酶抑制、诱导凋亡、作用于DNA等。本文简要综述了近几年(2010²014年)苯并噻唑衍生物在抗肿瘤药物研究方面的一些新发现。     

Structure-activity relationships of the lissoclinamides: cytotoxic cyclic peptides from the ascidian Lissoclinum patella

Two new lissoclinamides (lissoclinamides 7 and 8) have been isolated from the aplousobranch ascidian Lissoclinum patella. These lissoclinamides are cyclic heptapeptides with the same structural features as lissoclinamides 4 and 5 reported earlier, containing an oxazoline ring, one proline, one valine, two phenylalanine residues, and thiazole and/or thiazoline rings. All four peptides have the same sequence of amino acids around the ring and differ from one another only in their stereochemistry or the number of thiazole and thiazoline rings. The cytotoxicities of the compounds were tested with human fibroblast and bladder carcinoma cell lines and normal lymphocytes. Slight changes in structure resulted in marked differences in the cytotoxicities of these compounds. The most potent is lissoclinamide 7, containing two thiazoline rings, which rivals didemnin B in cytotoxicity in vitro.