Design, synthesis, and biological evaluation of a second generation of pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidines as potent and selective A2A adenosine receptor antagonists

New A2A adenosine receptor antagonists in the series of pyrazolo[4, 3-e]-1,2,4-triazolo[1,5-c]pyrimidines, bearing oxygenated substituents on the phenylalkyl chains on the 7-position, have been synthesized. The compounds were tested in binding and functional assays to evaluate affinity, potency, and selectivity for rat A2A compared to rat A1 and human A3 receptor subtypes. The most interesting compounds (5d,e,h) were tested also in binding to human A1 and A2A adenosine receptors. They showed very good affinity (Ki = 0.94 nM for compound 5h) and interesting selectivity with respect to both rA1 and hA3 (compound 5h: rA1/rA2A = 787, hA3/rA2A > 10 000). These important findings make this new series of compounds the first really selective for A2A adenosine receptors. Thermodynamic parameters were evaluated; all the tested compounds displayed an enthalpy-driven binding as expected for antagonists. Moreover, compound 5h showed a negative entropy value. The highly negative enthalpic and entropic contributions could mean that 5h fits very well in the binding site where, probably, an electrostatic interaction is present associated to a scarce solvent reorganization around the receptor binding site. These compounds deserve to be further developed to assess their potential for treatment of neurodegenerative disorders such as Parkinson's disease.     

Studies on arylfuran derivatives-Part VI. Synthesis, characterization and antibacterial activities of some 6-(5-aryl-2-furyl)-1,2,4-triazolo [3,4-b]-1,3,4-thiadiazoles and 6-(5-nitro-2-furyl)-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles

A series of 4-[5-aryl-2-furfurylidene]amino-3-mercapto-5-substituted-1,2,4-tri azoles and 4-[5-Nitro-2-furfurylidene]amino-3-mercapto-5-substituted-1,2,4-tr iazoles have been synthesized and were converted into 1,2,4-triazolo [3,4-b]-1,3,4-thiadiazoles. These triazolothiadiazoles are also synthesized by an alternative method in better yields employing arylfuroic acids and s-triazoles in the presence of phosphorus oxychloride. The newly synthesized compounds are screened for their antibacterial properties.     

Studies on substances with antiblastic activity. IX. Anthramycin and analogs. IX. Synthesis of 7-methoxy-8-hydroxy-10,11-dihydro-5H-pyrrolo[2,1-c] [1,4] benzodiazepine and other compounds related to oxotomaymycin

The synthesis of some pyrrolobenzodiazepine derivatives related to oxotomaymycin, an antibiotic recovered together with tomaymycin from fermentation broths of Streptomyces achromogenes var. tomaymycetics, is described. Reaction between 2-nitro-4-benzyloxy-5-methoxybenzylbromide and pyrrole-2-carboxyaldehyde afforded 1-(2-nitro-4-benzyloxy-5-methoxybenzyl)pyrrole-2-carboxyaldehyde. Catalytic reduction of this compound with hydrogen in the presence of Pd/C gave 10,11-dihydro-8-hydroxy-7-methoxy-5H-pyrrolo[2.1-c] [1,4]benzodiazepine. Amides obtained from condensation between 2-nitro-4-benzyloxy-5-methoxybenzoic acid chloride and proline or hydroxyproline were reduced catalytically to 2,3-dihydro-8-hydroxy-7-methoxy-1H-pyrrolo [2,1-c] [1,4]benzodiazepine-5,11 (10H, 11aH)-dione and its 2-hydroxyderivative respectively. The synthesis of 10,11-dihydro-8-hydroxy-9-methoxy-5-pyrrolo [2,1-c] [1,4]benzodiazepine is also reported.     

Cardiovascular characterization of pyrrolo[2,1-d][1,5]benzothiazepine derivatives binding selectively to the peripheral-type benzodiazepine receptor (PBR): from dual PBR affinity and calcium antagonist activity to novel and selective calcium entry blockers

The synthesis and cardiovascular characterization of a series of novel pyrrolo[2,1-d][1,5]-benzothiazepine derivatives (54-68) are described. Selective peripheral-type benzodiazepine receptor (PBR) ligands, such as PK 11195 and Ro 5-4864, have recently been found to possess low but significant inhibitory activity of L-type calcium channels, and this property is implicated in the cardiovascular effects observed with these compounds. In functional studies both PK 11195 (1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3-isoquinolinecarboxa mide) and Ro 5-4864 (4'-chlorodiazepam) did not display selectivity between cardiac and vascular tissue. Therefore, several 7-(acyloxy)-6-arylpyrrolo[2,1-d][1,5]benzothiazepines, potent and selective peripheral-type benzodiazepine receptor ligands recently developed by us (3, 7-20), were subjected to calcium channel receptor binding assay. Some of these compounds showed an unexpected potency in displacing the binding of [3H]nitrendipine from L-type calcium channels, much higher than that reported for PK 11195 and Ro 5-4864 and equal to or higher than that of reference calcium antagonists such as verapamil and (+)-cis-diltiazem. Specifically, in rat cortex homogenate, our prototypic PBR ligand 7-acetoxy-6-(p-methoxyphenyl)pyrrolo[2,1-d][1,5]benzothiazepine (3) showed an IC50 equal to 0.13 nM for inhibition of [3H]nitrendipine binding. Furthermore, in functional studies this compound displayed a clear-cut selectivity for cardiac over vascular tissue. Comparison of calcium antagonist activity on guinea pig aorta strips with the negative inotropic activity, determined by using isolated guinea pig left atria, revealed that 3 displayed higher selectivity than the reference (+)-cis-diltiazem. Thus, the pyrrolobenzothiazepine 3 might represent a new tool for characterizing the relationship between the PBR and cardiac function. Furthermore, we have also investigated the structural dependence of binding to PBR and L-type calcium channels, and this study allowed us to identify a new class of potent calcium channel blockers selective for cardiac over vascular tissue, with no affinity for PBR. A number of structure-activity relationship trends have been identified, and a possible explanation is advanced in order to account for the observed differences in selectivity. Three structural features, namely, (i) the saturation of the C(6)-C(7) double bond, with a consequent higher molecular flexibility, (ii) the presence of a substituent in the benzofused ring, and (iii) a basic side chain at C-10 of the pyrrolobenzothiazepine ring system, were found to be responsible for potent L-type calcium channel antagonism and clear-cut selectivity for cardiac over vascular tissue. Among the synthesized compounds the pyrrolobenzothiazepine 62 was found to be the most promising selective calcium channel blocker. Additionally, the molecular structure determination of the key intermediate 48 by X-ray diffraction, molecular modeling, and NMR analysis is reported.     

Synthesis of the selective 5-hydroxytryptamine 4 (5-HT4) receptor agonist (+)-(S)-2-chloro-5-methoxy-4-[5-(2-piperidylmethyl)-1,2,4-oxadiazol-3-y l]aniline

A 52-year-old white woman was first diagnosed with a tumor of the right optic nerve in 1972. She remained asymptomatic until 1992, when she had a seizure on the left side of her body from a frontoparietal glioblastoma multiforme. Ophthalmic examination revealed enlargement of the eye tumor. This case provides clinical documentation spanning 20 years of a growing, pigmented tumor of the optic nerve head shown histopathologically to be a retinal pigment epithelial adenoma.     

A search for new 5-HT1A/5-HT2A receptor ligands. In vitro and in vivo studies of 1-[omega-(4-aryl-1-piperazinyl)alkyl]indolin-2(1H)-ones

A series of 1-?omega-(4-aryl-1-piperazinyl)alkyl]indolin-2(1H)-one derivatives 2-14 was synthesized in order to obtain ligands with a dual 5-HT1A/5-HT2A activity. The majority of those compounds (2-5, 7, 10-13) exhibited a high 5-HT1A (Ki = 2-44 nM) and/or 5-HT2A affinity (Ki = 51 and 39 for 5 and 7, respectively). Induction of lower lip retraction (LLR) and behavioral syndrome and inhibition of these effects evoked by 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) were used for determination the agonistic and antagonistic activity, respectively, at 5-HT1A receptors. The 5-HT2A antagonistic activity was assessed by the blocking effect on the head twitches induced by (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) in mice. Two of the tested compounds, 1-?3-[4-(3-chlorophenyl)-1-piperazinyl]propyl?-6-fluoroindolin-2(1 H)-one (5) and 1-?3-[4-(2-methoxyphenyl)-1-piperazinyl]propyl?indolin-2(1H)-one (7), demonstrated a high 5-HT1A/5-HT2A affinity and an in vivo antagonistic activity towards both receptor subtypes.     

Design, Synthesis and Biological Evaluation of 2-Aroyl-3-aryl-6,7-dihydro-5H-furo[3,2-g]chromen Derivatives as a Novel Series of Estrogen Receptor Modulators

Based on the principles of the bioisosterism,combination of the active substructures of selective estrogen receptor modulators which are currently therapeutic agents available for the prevention and treatment of various estrogen dependent diseases,and structural optimization,a novel series of 2-aroyl-3-aryl-6,7-dihydro-5H-furo[3,2-g]chromen derivatives was designed as potent selective estrogen receptor modulators via molecular docking.The target compounds.have been synthesized,and characterized by IR,proton NMR,ESI-MS,elemental analysis and evaluated for their antitumor activity against human osteosarcoma U2OS-EGFP-4FI2G cell line.Some target compounds showed good inhibition effects on U2OS-EGFP-4F 12G cell line and the preliminary structure-activity relationships were discussed.     

Synthesis and QSAR of some 3-amino-2-(substituted)aminomethyl-5,6-disubstituted thieno[2,3-d]pyrimidin-4(3H)-ones as novel H1-receptor antagonists

The plasma concentrations of two bone matrix proteins (osteocalcin, osteonectin) were monitored in 56 samples from 14 patients receiving renal transplants and the values compared with serum bone alkaline phosphatase mass concentrations and osteotropic hormone levels (parathyroid hormone, calcitriol). There were no significant changes in the concentrations of plasma osteonectin at any time after transplantation, as compared with the values before transplantation (P > 0.1). None of the plasma samples showed osteonectin levels above the reference interval. There was a weak but significant relationship between platelet counts and plasma osteonectin levels (r = +0.322; P < 0.05). Osteocalcin showed a marked decrease of the values 1 week following transplantation as compared with the values before transplantation without further change of the values 1 and 3 months after transplantation (P > 0.5) whereas 3 months after transplantation bone alkaline phosphatase levels were higher than before transplantation (P < 0.05). Multiple regression analysis (performed with data from 42 samples obtained after transplantation) revealed serum creatinine as an independent predictor of plasma osteocalcin whereas serum calcitriol was an independent predictor of serum bone alkaline phosphatase (P < 0.05). No correlation was observed between serum calcitriol/plasma parathyroid hormone on the one hand and plasma osteocalcin on the other (P > 0.05). After transplantation there was a lack of correlation between serum bone alkaline phosphatase mass concentrations and plasma osteocalcin values (P > 0.05). In conclusion, serum bone alkaline phosphatase should be preferred to bone matrix proteins for the assessment of bone metabolism in patients receiving renal transplants: (a) bone alkaline phosphatase-but not osteocalcin-is significantly correlated with calcitriol and adequately reflects increased bone formation after renal transplantation; (b) interpretation of osteocalcin values is severely hampered by their strong correlation with serum creatinine concentrations; (c) plasma osteonectin determinations are not useful for monitoring bone formation.