Development of an HPLC/UV assay for the evaluation of inhibitors of human recombinant monoacylglycerol lipase.

Monoacylglycerol lipase (MAGL) is a membrane-associated cytosolic serine hydrolase which catalyses the hydrolysis of the endocannabinoid 2-arachidonoylglycerol into arachidonic acid and glycerol. MAGL represents the link between the endocannabinoid and the eicosanoid system indeed its inhibition enhances endocannabinoid signalling and lowers eicosanoid production. Here we present a radioactive-free, sensitive and solid HPLC-UV based method to evaluate MAGL activity by using 4-nitrophenylacetate (4-NPA) as substrate. The enzymatic activity is measured by quantifying the 4-nitrophenol (PNP) (λ = 315 nm) formation on a C18 stationary phase. The method was validated by calculating IC50 values of the reference inhibitors JZL184, CAY10499 and JW642 and confirming the irreversible and non-competitive mechanism of inhibition for JZL184. Furthermore in order to resemble the catalytic conditions of MAGL at cell membrane level, the surfactant Triton X-100 was added, as a micelle forming agent and 4-nitrophenyldodecanoate (4-NPDo) was used as lipophilic substrate for MAGL. The data obtained confirmed that the HPLC method is an alternative, radioactive-free approach for the screening and characterization of new MAGL inhibitors. Finally this assay prevents, in an unequivocal manner, any interference related to the intrinsic absorbance of screened compounds or metabolites generated upon enzymatic cleavage which could seriously affect the assay readout.

Pharmacokinetics of intravenous and intramuscular parecoxib in healthy Beagles.

Parecoxib is an inactive pro-drug that is rapidly converted to valdecoxib, a selective cyclooxygenase (COX)-2 inhibitor registered for the management of post-operative pain in humans. Recent studies have suggested that parecoxib has excellent clinical efficacy and safety in veterinary species. The aim of the current study was to assess the pharmacokinetics of parecoxib and valdecoxib after intravenous (i.v.) and intramuscular (i.m.) administration. Seven healthy male Beagle dogs received 2.5 mg/kg parecoxib by either the i.v. or i.m. route in a cross-over design, with the alternative route of administration used 1 week later. The plasma concentrations of both analytes were detected according to a previously validated method using high performance liquid chromatography with fluorescence detection (HPLC-FL). No adverse effects were observed in any animal during the study. For both routes of administration, parecoxib was rapidly and almost completely converted to valdecoxib. The parecoxib/valdecoxib area under the curve (AUC) ratio for both routes of administration was 1.4. The half-life of valdecoxib was about 2 h, which was shorter than reported for humans, although the plasma concentrations following both routes of administration were likely to be effective for analgesia. The absolute bioavailability of parecoxib was 66%. The pharmacokinetic features of parecoxib make it suitable for treatment of acute pain in the canine species.

Simultaneous detection and quantification of parecoxib and valdecoxib in canine plasma by HPLC with spectrofluorimetric detection: development and validation of a new methodology.

Parecoxib is the injectable prodrug of valdecoxib, a cicloxygenase-2 selective drug, currently used in human medicine. Recent studies have suggested both its excellent clinical effectiveness and wide safety profile. The aim of the present study was to develop and validate a new high-performance liquid chromatography (HPLC) with spectrofluorimetric detection method to quantify parecoxib and valdecoxib in canine plasma. Several parameters both in the extraction and the detection method were evaluated. The applicability of the method was determined by administering parecoxib to one dog: the protocol provided the expected pharmacokinetic results. The final mobile phase was acetonitrile: AcONH(4) (10 mM; pH 5.0) 55:45, v/v, with a flow rate of 0.4 mL min(-1), and excitation and emission wavelengths of 265 and 375 nm, respectively. The analytical column was a reverse-phase C18 ODS2 3-µm particle size. Protein precipitation in acidic medium followed by two successive liquid-liquid steps was carried out. The best extraction solvent was cyclohexane:Et(2)O (3:2, v/v) that gave recoveries ranging from 81.1% to 89.1% and from 94.8% to 103.6% for parecoxib and valdecoxib, respectively. The limits of quantification were 25 and 10 ng mL(-1) for parecoxib and valdecoxib, respectively. The chromatographic runs were specific with no interfering peaks at the retention times of the analytes, as confirmed by HPLC-mass spectrometry experiments. The other validation parameters were in agreement with the European Medicines Evaluation Agency and International Conference on Harmonisation guidelines. In conclusion, this method (extraction, separation and applied techniques) is simple and effective. This is the first time that use of a HPLC with spectrofluorimetric detection technique to simultaneously detect parecoxib and valdecoxib in plasma has been reported. This technique may have applications for pharmacokinetic studies.

Determination of tramadol and metabolites by HPLC-FL and HPLC-MS/MS in urine of dogs.

Tramadol is a centrally acting analgesic drug used in veterinary and human clinical practice. Its metabolism has been largely characterized in human being but is still long to be comprehended in several animal species, especially in the dog. The aim of the present study was to develop and validate a new analytical procedure to investigate HPLC the metabolization/elimination process tramadol in urine of dogs by HPLC-FL or HPLC-MS/MS. A single oral dose of tramadol (4mg/kg) was administered to 4 male Beagle dogs and the urine was naturally collected. This matrix either hydrolyzed than un-hydrolyzed was extracted with different blends of solvents to detect the total or free form of the analytes, respectively. The present method allowed to obtain good selectivity, accuracy, precision and recoveries without the need of time consuming or expensive clean up steps. The short chromatographic time courses allowed this analysis to be proposed for routine purposes. The HPLC-MS/MS detected in the urine two metabolites (M6 and M7) considered negligible in humans. The low LOQ showed that the method could be useful for the determination of the illegal use of this drug in race-dogs' urine.

Anti-Ro/SSA antibodies in rheumatoid arthritis: clinical and immunologic associations.

OBJECTIVE: To assess the prevalence of anti-Ro/SSA in RA and to analyse clinical and serological features of anti-Ro/SSA positive patients with RA. METHODS: 195 consecutive patients affected by RA were studied by counterimmunoelectrophoresis and ELISA for the detection of anti-Ro/SSA antibodies. Anti-Ro were found in 12 patients, with a prevalence of 6%. These 12 patients were pooled with other 15 patients known to have anti-Ro/SSA antibodies and RA, in order to evaluate their clinical and laboratory features. RESULTS: Anti-Ro positive patients showed a common pattern of joint involvement at onset and a comparable progression of disease compared to anti-Ro negative subjects. In addition, extra-articular manifestations (such as xerophthalmia, xerostomia, scleritis, oral ulcers and amyloidosis) and peculiar autoantibody profile (hypergammaglobulinemia, anti-dsDNA and AMA) were found significantly associated to anti-Ro/SSA positivity. Even though DMARDs withdrawals were more frequently detected in anti-Ro/SSA patients, especially when using gold salts, no statistical difference between the two groups was detected. In addition, anti-TNFalpha treatment did not cause further progression of autoimmunity neither on laboratory nor on clinical ground. CONCLUSION: Anti-Ro/SSA can be detected in about 6% of patients affected by RA. These patients presented a peculiar clinical picture characterised by extra-articular manifestations some of which are known to be anti-Ro/SSA correlated, while others are more disease-specific (amyloidosis, episcleritis). Anti-Ro/SSA are significantly associated with other autoantibodies not specific for RA such as anti-dsDNA and AMA. Treatment with anti-TNF drugs did not cause further progression of autoimmunity neither on laboratory nor on clinical ground.

Synthesis and antiplatelet activity of some 2,7-di(N-cycloamino)-3-phenyl-1,8-naphthyridine derivatives.

Several 2,7-di(N-cycloamino)-3-phenyl-1,8-naphthyridine derivatives were synthesized and tested for their ability to inhibit human platelet aggregation in vitro induced by arachidonic acid, collagen and ADP. Only five compounds showed any appreciable activity, and the results of all the active derivatives were similar to those of papaverine in the test with arachidonic acid and collagen. Moreover, the most active compounds were investigated in the test with ADP and again showed a significant activity. The tested compounds that possessed the best activity were also shown to increase the c-AMP level significantly without involving the adenylyl cyclase system.

Synthesis and evaluation of antihypertensive activity of 1,8-naphthyridine derivatives. Part X.

A series of 4-(N-methylencycloalkylamino)-1,8-naphthyridine derivatives variously substituted in positions 2 and 7 were synthesized and pharmacologically investigated for possible antihypertensive activity. These compounds were tested to determine a possible vasodilator mechanism of action. Compounds 22, 23, 27-29, 47 and 48 showed satisfactory levels of potency (pIC(50)>5), which in one case (compound 23) reached a really interesting value (pIC(50) 6.92). Furthermore, for some selected compounds (19, 22, 23, 26, 28, 29, 47), the vasorelaxing activity was also evaluated in the presence of the guanylate cyclase blocker ODQ or of the adenylate cyclase blocker SQ 22536, and some of these can be considered as possible guanylate-cyclase inhibitors. Finally, compounds 19, 22 and 23 were also tested in the presence of the ATP-sensitive potassium channel blocker glybenclamide and seem to possess activating properties on these potassium channels.

Synthesis and beta-blocking activity of (R,S)-(E)-oximeethers of 2, 3-dihydro-1,8-naphthyridine and 2,3-dihydrothiopyrano[2, 3-b]pyridine:potential antihypertensive agents - part IX.

The synthesis of oximeethers of 2,3-dihydro-1,8-naphthyridine and 2, 3-dihydrothiopyrano[2,3-b]pyridine is described. These compounds exhibit a selective beta-blocking activity, with a selectivity towards beta(2)-receptors. Groups in the N(1) position giving rise to a considerable steric hindrance led to a higher beta(2)-blocking selectivity, whereas groups creating a moderate hindrance caused a weak but significant decrease in beta(2)-antagonist potency. Substitution of the N(1)-R group with a sulfur atom led to compounds possessing beta(1)-, beta(2)- and beta(3)-blocking properties. Compounds 9c(1) and 10a(1) showed a beta(3)-antagonist activity slightly lower than that of propranolol.

A novel class of highly potent and selective A1 adenosine antagonists: structure-affinity profile of a series of 1,8-naphthyridine derivatives.

A series of 1,8-naphthyridine derivatives (12-36), bearing a phenyl group in position 2 and various substituents in positions 4 and 7, were synthesized in an attempt to obtain potent, selective antagonists for the A1 adenosine receptor subtype. The compounds were tested to evaluate their affinity for A1 compared with A2A and A3 adenosine receptor subtypes. In binding studies in bovine brain cortical membranes, most of the compounds showed an affinity for A1 receptors in the low nanomolar range and two in the subnanomolar range with an interesting degree of A1 versus A2A and A3 selectivity. Comparison of the 4-substituted derivatives indicated that 4-OH substitution, with a 4-quinoid structure, causes an increase in the A1 and A2A affinity and generally also in A1 selectivity. The kind of substitution in position 7 can greatly modulate the affinity: the most interesting substituents in this position seemed to be electron-withdrawing groups; in particular the 7-chloronaphthyridine 25d showed a remarkable selectivity (A2A/A1 ratio of 670, A3/A1 ratio of 14,000) associated with a higher A1 affinity (Ki = 0.15 nM). NMR studies on these compounds 12-36 indicated that the 4-OH-substituted ones prefer the tautomer in which the oxygen in position 4 is in the quinoid form and the nitrogen in position 1 is protonated. Theoretical calculations are in agreement with the NMR data.

Substituted 1,2,3-triazolo[1,5-a]quinazolines: synthesis and binding to benzodiazepine and adenosine receptors.

This paper reports the synthesis and evaluation of the biological affinity towards benzodiazepine and A(1) and A(2A) adenosine receptors of some 3-ethoxycarbonyl or 3-phenyl-substituted 1,2, 3-triazolo[1,5-a]quinazolines. Starting from the appropriate chloro-substituted phenylazides, the series of 7 or 8 chloro-substituted triazoloquinazolines were prepared. Nitration reactions of the triazoloquinazoline ring and chlorination reactions of the hydroxyl group in the 5 position of the same ring are also reported. By nucleophilic displacement of halogen, the corresponding 5-amino derivatives and some analogous derivatives bearing cyclohexylamino and p-toluidino substituents were obtained. The binding assays showed a generalized decrease in the affinity towards the benzodiazepine receptors and confirmed a moderate affinity towards the A(1) adenosine receptors in comparison with the previously studied triazoloquinazoline derivatives.

Synthesis and antiplatelet activity of some 3-phenyl-1,8-naphthyridine derivatives.

A series of 2-cycloalkylamino-3-phenyl-1,8-naphthyridine derivatives, variously substituted in the 6- and 7-positions were synthesized and tested for their ability to inhibit human platelet aggregation in vitro induced by arachidonate, collagen and ADP. Compounds 5a,b, 7a,b, 8a and 10c,d showed a remarkable activity similar to that of indomethacin in the test with arachidonate and collagen. In the test with ADP only compound 8a showed a significant activity. The presence of a morpholinyl or piperidinyl group in position 2 and of a chloro or methoxy group in position 7 of the 1,8-naphthyridine nucleus seem to favour a higher activity. However on the basis of the pharmacological results, no structure-activity relationship can be deduced. Compounds 5b and 7b, which possess the best activity in the arachidonate test, were also shown to increase the c-AMP level significantly, without involving the adenylyl cyclase system.

Incidence of antiperinuclear factor in patients with psoriatic arthritis.

Antiperinuclear factor (APF) is considered a disease marker of rheumatoid arthritis (RA) and its diagnostic value is obvious in patients who are seronegative for rheumatoid factor (RF) activity. We have evaluated APF positivites in 76 patients with psoriatic arthritis, 38 uncomplicated psoriatic patients, 119 patients with non-inflammatory rheumatic diseases (NIRD), 36 RF- and 123 RF + RA patients and 204 healthy controls. APFs were investigated with an indirect immunofluorescence (IIF) test using epithelial cells from human buccal mucosa as a substrate. 6/76 (7.9%) PA patients were APF+. The incidence was greater than in healthy controls (2/204; p < 0.01) and similar to the incidences in patients with uncomplicated psoriasis (1/38; p = NS) and patients with non-inflammatory rheumatic disease NIRD (5/119; p = NS). However, the incidence was much lower than in RF- (19/36; p < 0.001) as well as RF+ (111/123; p < 0.001) RA patients. Finally, we emphasise that 3 out of 6 APF positivities shown by PA patients were found in our 3 patients with pustolotic arthroosteitis, a new specific entity in the spectrum of PA.

Antiperinuclear factor in psoriatic arthropathy.

BACKGROUND: Antiperinuclear factor (APF) is an autoantibody directed against (pro)-filaggrin molecules. OBJECTIVE: We evaluated whether APF determination is useful for the diagnosis of psoriatic arthritis (PA). METHODS: We determined APF titers in sera from patients with PA (n = 76), psoriasis vulgaris (n = 38), noninflammatory rheumatic diseases (NIRDs, n = 119), rheumatoid arthritis (RA, n = 159) both with negative (n = 36) and positive (n = 123) rheumatoid factor (RF) tests, as well as from 204 healthy controls. We used an indirect immunofluorescence test on epithelial cells from human buccal mucosa as a substrate. RESULTS: In patients with PA, 7.9% of the serum samples were APF-positive. The incidence was greater than in healthy controls (1.0%; P < .01), similar to those with uncomplicated psoriasis (2.6%; P = NS) and NIRDs (4.0%; P = NS), and lower than in RF-negative (52.7%; P < .001) and RF-positive (90.2%; P < .001) patients with RA. Three APF-positive patients with PA had symmetric joint involvement and 3 had pustulotic arthroosteitis. CONCLUSION: The APF test may be useful in differentiating PA from RA, and APF may be specific for two PA subgroups.

1,2,3-Triazolo[1,5-a][1,4]- and 1,2,3-triazolo[1,5-a]-[1,5]benzodiazepine derivatives: synthesis and benzodiazepine receptor binding.

This paper reports the synthesis of new 1,2,3-triazolo[1,4]benzodiazepine and 1,2,3-triazolo[1,5]benzodiazepine derivatives and their evaluation toward benzodiazepine receptors. Receptor affinity gradually and remarkably increases by moving the nitrogen atom of the central ring from position 3 through 4 to position 5, to give the most effective compound 6a (Ki = 150 nM). N-methylation of the diazepine ring (7a) lowers receptorial binding. Introduction of a chlorine atom on the benzene ring doubles the Ki value (6b) which remains unaltered by the N-methylation (7b).

Novel 3-aralkyl-7-(amino-substituted)-1,2,3-triazolo[4,5-d]pyrimidines with high affinity toward A1 adenosine receptors.

Three series of several 1,2,3-triazolo[4,5-d]pyrimidine derivatives bearing various amino substituents at the 7 position and one of three lipophilic substituents at the 3 position (benzyl, phenethyl, or 2-chlorobenzyl) were prepared starting from the corresponding 7-chloro compounds, by nucleophilic substitution by the appropriate amine. Radioligand binding assays at bovine brain adenosine A1 and A2A receptors showed that some compounds possessed a high affinity and selectivity for the A1 receptor subtype. In particular the biological results suggested the compounds bearing cycloalkylamino (cyclopentyl- and cyclohexylamino) or aralkylamino (alpha-methylbenzyl- and 1-methyl-2-phenylethylamino or amphetamino) substituents at the 7 position were the most active derivatives. The best lipophilic substituent at the 3 position was the 2-chlorobenzyl (A1 affinity Ki < 50 nM) followed by the benzyl and then the phenethyl groups. This pattern of structure-activity relationship (SAR) was similar to that previously reported for analogous 1,2,3-triazolopyridazino derivatives (Biagi et al., 1994, 1995, 1996) except for the compounds bearing substituted aromatic amines which presented a generalized and strong decrease of the A1 receptor affinity. These facts allowed us to attribute to these molecules a binding mode within the A1 adenosine receptor analogous to that of the corresponding triazolopyridazines.

Synthesis and evaluation of antimycobacterial activity of 4-phenyl-1,8-naphthyridine derivatives.

Some 4-phenyl-1,8-naphthyridine derivatives with a piperazino group in the 2- and/or 7-position have been synthesized and evaluated for their tuberculostatic activity. The compounds 1, 6, 10, 17b,c and 19i showed a marked activity against Mycobacterium tuberculosis H37Rv. For this series of compounds, submitted to biological screening, no structure-activity relationship can be deduced.

1,2,3-Triazolo [4,5-d] pyridazines--V. Preparation and adenosine receptor binding of new 4-amino derivatives.

This paper reports the continuation of studies on the 4-aminosubstituted 1,2,3-triazolo [4,5-d] pyridazine derivatives which had shown binding affinity towards A1-adenosine receptors. 1-Benzyl derivatives bearing new amines and new 1-(substituted benzyl) derivatives were prepared and tested. The biological results showed that some compounds possessed high affinity (approximately 30-70 nM) and good selectivity toward the A1-adenosine receptors. Further information about structure-biological activity relationships was aquired.

Synthesis and antimicrobial activity of benzo[a]dihydrocarbazole and benzotetrahydrocyclohept[1,2-b]indole derivatives.

A certain number of benzodihydrocarbazoles and benzotetrahydrocycloheptindoles were synthesized and tested for their antimicrobial activity. Compounds substituted on the nitrogen of the tetracyclic systems with a dimethylaminopropyl chain showed an antibacterial activity directed almost exclusively towards Gram-positive bacteria, while their N-unsubstituted analogs were completely inactive.

(E)-(arylmethyleneaminoxy)acetamides as analogues of neuroleptic benzamides: synthesis and D2-dopaminergic binding affinity.

Some type B (E)-(arylmethyleneaminoxy)acetamides were synthesised as analogues of type A neuroleptic and antipsychotic benzamides, in which the aromatic group is substituted by a (methyleneaminoxy)methyl moiety (C = NOCH2, MAOMM). Theoretical studies were performed in order to verify whether conformational analogies could exist between type A and type B compounds. Type B compounds were tested for their D2-dopaminergic binding affinity which represents a valid indication of their potential neuroleptic and antipsychotic properties. Biological results indicate that the MAOMM is not able to substitute the aromatic group effectively in the field of neuroleptic benzamides. The results are discussed in the light of the structural analogies and the differences between the MAOMM and the aryl.

Clinical heterogeneity of rheumatoid arthritis and the antiperinuclear factor.

OBJECTIVE: To assess the diagnostic and prognostic power of antiperinuclear factor (APF) and to identify a specific pattern of rheumatoid arthritis (RA) of different evolution and prognosis. METHODS: One hundred and fifty-nine sera from patients with RA, 280 sera from patients with other rheumatic diseases and 204 sera from healthy subjects were examined for APF. RESULTS: Sensitivity and specificity of the test were, respectively, 0.82 and 0.99 when 1:80 serum dilution was considered positive but 0.84 and 0.92 when tested at the currently used 1:5 serum dilution. According to the data obtained from APF and rheumatoid factor (RF) testing, patients with RA were subdivided in 4 groups. Clinical and demographic features for each group were analyzed. RF+ and/or APF+ patients showed a common pattern of disease, whereas RF-/APF- patients showed fewer extraarticular manifestations (p < 0.02) including Sjögren's syndrome (p < 0.04) and an unusual onset of the disease characterized by an involvement of large joints (p < 0.0001). Higher titer of APF was detected at the onset of the disease than in longstanding RA (p < 0.02). CONCLUSIONS: APF is a valuable diagnostic tool and a useful additional marker for RA. 1:80 serum dilution allows more specificity without substantial loss of sensitivity. A specific pattern of RA can be identified on the basis of APF status.