Sensitive SPE-HPLC method to determine a novel angiotensin-AT1 antagonist in biological samples.

A high-performance liquid chromatography (HPLC)-method after solid-phase extraction (SPE) has been developed in order to determine a new angiotensin-AT1 antagonist, i.e. CR 3210 (C27H24N8; MW = 460.54), 4-[4-[(2-ethyl-5,7-dimethylimidazo[4,5-b]pyridin-3-yl)methyl]phenyl]-3-(2H-tetrazol-5-yl)quinoline in rat plasma and urine after oral administration to Sprague-Dawley rats. CR 3210 and the internal standard (IS) CR 1505 (loxiglumide), i.e. 4-[(3,4-dichlorobenzoyl)amino]-5-[(3-methoxypropyl)pentylamino]-5-oxopentanoic acid, were isolated from rat urine and plasma by solid-phase extraction. The procedure was optimized regarding the sorbent extraction material, the pH in the conditioning solution, the washing step, the dry time and the type of elution solvent. The separation was performed by reversed-phase high-performance liquid chromatography with ultraviolet detection. The samples were injected onto the analytical column (Tracer Extrasil ODS1) and detected at 238 nm, giving a capacity factor of 1.87 for CR 3210 and 1.10 for the internal standard. The selectivity of the method was satisfactory. The mean recovery of CR 3210 from spiked rat plasma was 68.5 at 75 ng/ml and 80.9 at 3000 ng/ml; the mean recovery of CR 3210 from spiked rat urine was 69.9 at 75 ng/ml and 78.6 at 3000 ng/ml. The lower limit of detection (LOD) was 14 ng/ml in plasma and 22 ng/ml in urine samples. The lower limit of quantification (LOQ) was taken as 30 ng/ml, the lowest calibration standard using 500 microl rat plasma and urine. The procedures were validated according to international standards with a good reproducibility and linear response from 30 to 3000 ng/ml, for either plasma or urine. The sensitivity of the method allowed for its application to pharmacokinetic studies.

Chiral 3,3'-(1,2-ethanediyl)-bis[2-(3,4-dimethoxyphenyl)-4-thiazolidinones] with anti-inflammatory activity. Part 11: evaluation of COX-2 selectivity and modelling.

Anti-inflammatory/analgesic 3,3'-(1,2-ethanediyl)-bis[2-(3,4-dimethoxyphenyl)-4-thiazolidinones] 1, obtained as racemic mixtures (a) and mesoforms (b), have two equivalent stereogenic centres (C-2 and C-2') and exist as RR, SS and RS isomers. The enantioseparation of 1a provided the single enantiomers that displayed different in vitro cyclooxygenase-1/cyclooxygenase-2 selectivity ratios. In particular the dextrorotatory compound is a highly selective COX-2 inhibitor and the levorotatory one is moderately selective. Instead, RS-meso isomer (1b) exhibited similar levels of inhibitory activity on both COX isozymes. The diastereo- and enantioselectivity has been explained by molecular modelling of RR, SS and RS compounds into COX-1 and COX-2 binding sites. Theoretical results indicated SS>RS>RR affinity order towards COX-2 isoenzyme, in agreement with in vitro and previous in vivo pharmacological results.

Synthesis and aldose reductase inhibitory activity of 5-arylidene-2,4-thiazolidinediones.

Several (Z)-5-arylidene-2,4-thiazolidinediones were synthesized and tested as aldose reductase inhibitors (ARIs). The most active of the N-unsubstituted derivatives (2) exerted the same inhibitory activity of Sorbinil. The introduction of an acetic side chain on N-3 of the thiazolidinedione moiety led to a marked increase in lending inhibitory activity, conducting to the discovery of a very potent ARI (4c), whose activity level (IC50=0.13 microM) was in the same range of Tolrestat. Moreover, the corresponding methyl esters (3), devoid of any acidic functionality, showed appreciable inhibitory activity similar to that of the N-unsubstituted compounds. It was also found that the substitution pattern on the 5-benzylidene moiety markedly influenced the activity of N-unsubstituted 2,4-thiazolidinediones 2, compounds with substituents at the meta position being generally more effective than the para-substituted ones; however, this SAR was not evidenced in acetates 3 and acids 4.

Synthesis and antiinflammatory, analgesic activity of 3,3'-(1,2-ethanediyl)-bis[2-aryl-4-thiazolidinone] chiral compounds. Part 10.

In this note, the synthesis and structure-activity relationships of a new series of 2R,2'R/2S,2'S and 2R,2'S-meso 3,3'-(1,2-ethanediyl)-bis[2-aryl-4-thiazolidinones] are described. Antiinflammatory activity was investigated by the carrageenin-induced paw edema test and analgesic activity by acetic acid writhing and hot plate tests in rats. All compounds displayed ulcerogenic effects and acute toxicity much lower than indomethacin and phenylbutazone. Meso isomers (b) showed better pharmacological profiles than corresponding racemates (a). Methoxy substitution patterns of the aryls on stereogenic carbons are generally the most favorable on the pharmacological profile.

Nickel(II) 2,6-diacetylpyridine bis(isonicotinoylhydrazonate) and bis(benzoylhydrazonate) complexes: structure and antimycobacterial evaluation. Part XI.

The reaction of 2,6-diacetylpyridine (dap) and isonicotinoyl- or benzoylhydrazide leads to bishydrazones H(2)dapin (1a) and H(2)dapb (1b), respectively. The condensation can either take place as a bimolecular kinetic process between the two reactants or as a monomolecular metal-templated synthesis in the presence of nickel(II) ions. In the latter case the reaction products are charged 2,6-diacetylpyridine bis(hydrazone) nickel(II) complexes, which can be easily deprotonated to neutral hydrazonates. Diffractometric analysis of one of these [Ni(dapb)](2) (8b) has shown a binuclear structure with two octahedral nickel(II) ions bridged by two helicoidal dap (bishydrazonates) in a spheroidal structure of C(2V) symmetry. The synthesized complexes 8 are promising as antimycobacterial agents against M. tuberculosis H37Rv. In particular, 8b displays significant activity (MIC=0.025 microg/mL) 10-fold higher than rifampin and equal to isoniazid, while its ligand is ineffective. Compound 8b is also capable of reducing HIV-induced cytopathogenic effect in human T(4 )lymphocytes.

Antimycobacterial in vitro activity of cobalt(II) isonicotinoylhydrazone complexes. Part 10.

Octahedral cobalt(II) complexes of isonicotinoylhydrazones, which were obtained from the primary antituberculous agent isoniazid, have been synthesised and characterised. Their antimycobacterial in vitro activity has been evaluated against Mycobacterium tuberculosis H37Rv: they exhibit MIC values ranging from < 0.1 to 0.39 microg/mL, showing them to be generally more active than previously reported analogous Cu(II) and Ni(II) complexes.

Isoniazid-related copper(II) and nickel(II) complexes with antimycobacterial in vitro activity. Part 9.

Isonicotinoylhydrazones 1, obtained by the primary antituberculous agent Isoniazid, have been used as monoanionic ligands (L) to prepare copper(II) 2 and nickel(II) 3 octahedral complexes of stoichiometry [MeL2(H2O)2]. Their antimycobacterial in vitro activity was evaluated against Mycobacterium tuberculosis H37Rv in comparison with the ligands. Complexes 2a, 2b, 2f, 3b, 3d and 3g displayed MIC values < or = 0.2 microg/mL.

Synthesis and in vitro antimicrobial and antitumoral screening of novel lipophilic isoniazid analogues. VI.

Various kinds of lipophilic analogues of isonicotinic acid hydrazide (Isoniazid) were synthesized and in vitro explored in a search for antimycobacterial agents with extended activity spectrum against pathogens responsible for the AIDS-associated diseases. The primary in vitro screening showed that a) isonicotinoylhydrazones 1a, 1b, 1d, 1e are more active than the parent drug against non-tubercular mycobacteria (MIC ranging between 0.5 and 4 micrograms/ml), b) isonicotinohydrazides 6b and 6e display interesting antibacterial activity on some Gram + and Gram-strains, and c) trifluoromethyl-containing compounds 1a and 2c inhibit the growth of several human tumor cell lines at doses between 10(-5) and 10(-6) M. On the contrary, none of the tested analogues significantly counteracts the cytopathogenicity induced by HIV and HSV viruses.

3,3'-Bi(1,3-thiazolidin-4-one) system. VIII. 3,3'-(1,2-Ethanediyl) derivatives and corresponding 1,1'-disulfones: synthesis, stereochemistry and antiinflammatory activity.

To deeply investigate the influence of lipophilicity, phenyl substitution patterns and stereo-chemistry on pharmacological profiles of chiral bisarylthiazolidinones, frequently endowed with stereoselective antiinflammatory, analgesic, antihistaminic activities, we synthesized and explored some 3,3'-(1,2-ethanediyl) analogues 1-4, along with their S-oxidized derivatives 5-8. Each derivative can be isolated as 2R, 2'R/2S, 2'S (a) and 2R, 2'S- or 2S, 2'R- meso (b) diastereomers, which were explored by means of carrageenin edema test, acetic acid writhing and hot plate tests, and also tested for gastrolesive potential and LD50. Independently of lipophilic and electronic features, disulfides 3b, 4b and disulfones 7a, 8a, 8b displayed interesting activity levels which appear to be mainly linked to the disubstitution pattern on benzenic rings.