Effects of anti-inflammatory [1, 2, 4]triazolo[4, 3-a] [1, 8]naphthyridine derivatives on human stimulated PMN and endothelial cells: an in vitro study.

BACKGROUND: 124 triazolo [4, 3-a]18naphthyridine derivatives (including NF161 and NF177) were tested for anti-inflammatory, analgesic and antipyretic properties and for their effects on spontaneous locomotor activity in mice and acute gastrolesivity in rats. Both NF161 and NF177 appeared to be anti-inflammatory and analgesic agents without toxic effects or acute gastrolesivity, but NF161 showed stronger anti-inflammatory activity, whereas NF177 was more active as analgesic. METHODS: An EIA kit was used to investigate the ability of NF161 and NF177 to affect prostaglandin E2 (PGE2) and prostacyclin (PGI2) production by human umbilical vascular endothelial cells (HUVEC). The compounds' effects on the production of reactive oxygen species (ROS) by human polymorphonuclear cells (PMNs) were studied in an in vitro cell model, evaluating inhibition of superoxide anion (O2-*) production induced by N-formylmethionyl-leucyl-phenylalanine (FMLP). Their effects on PMN adhesion to HUVEC were also investigated; they were incubated with PMNs and endothelial cells (EC) and challenged by stimuli including Platelet Activating Factor (PAF), FMLP, Phorbol Myristate Acetate (PMA), Tumor Necrosis Factor-alpha (TNF-alpha) and Interleukin-1beta (IL-1beta). Adhesion was quantitated by computerized micro-imaging fluorescence analysis. RESULTS: Neither compounds modified PGE2 or PGI2 production induced by IL-1alpha. O2-* production and myeloperoxidase release from PMNs stimulated by FMLP was inhibited in a dose- but not time-dependent manner by both 18naphthyridine derivatives, NF161 being statistically more active than NF177 (P < 0.01). The compounds inhibited adhesion evoked by the pro-inflammatory stimuli PAF, FMLP, TNF-alpha and IL-1beta in a concentration-dependent manner in the 10(-6)-10(-4)M range, being more active when PAF was used as stimulus and inactive when cells were challenged by PMA. Both compounds acted both on PMN and HUVEC. CONCLUSION: Considering the interesting anti-inflammatory effects of these compounds in in vivo models and the absence of acute gastrolesivity, the study improved knowledge of anti-inflammatory properties of NF161 and NF177, also demonstrating their potential in vitro, through inhibition of O2-* production, myeloperoxidase release and PMN adhesion to HUVEC. Negative results on PG production suggest a cyclooxygenase (COX)-independent mechanism.

Synthesis and in vitro inhibitory activity on human platelet aggregation of novel properly substituted 4-(1-piperazinyl)coumarins.

Pursuing our chemical and biological studies in this field, we described the multistep preparation of the new 5-, 6-, or 7-alkoxy and 7-alkoxy-8-methyl substituted 4-(1-piperazinyl)coumarins 5d-v, as well as the in vitro evaluation of their inhibitory activity on human platelet aggregation induced in platelet-rich plasma by ADP, collagen or the Ca(2+) ionophore A23187. Compounds 5h-j,p,r-u showed notably high activity towards all the platelet aggregation inducers used, and the most active one, 8-methyl-4-(1-piperazinyl)-7-(3-pyridylmethoxy)coumarin (5t), proved to be a potent in vitro antiplatelet agent.

Mechanisms involved in the antiplatelet activity of 8-methyl-4-(1-piperazinyl)-7-(3-pyridinylmethoxy)-2H-1-benzopyran-2-one (RC414).

The effect on human platelets of 8-methyl-4-(1-piperazinyl)-7-(3-pyridinylmethoxy)-2H-1-benzopyran-2-one (RC414) was tested in vitro by measuring aggregation induced by several agonists, cAMP and cGMP levels, cAMP phosphodiesterase and PKC activities and [Ca2+]i. The RC414 effect on nitric oxide production was also evaluated. RC414 in a dose-dependent manner inhibited aggregation both in platelet rich plasma and in washed platelets. It was particularly effective in platelets challenged by collagen, ADP and thrombin: IC50 values are 0.51 +/- 0.12 microM, 0.98 +/- 0.36 microM and 1.00 +/- 0.15 microM, respectively. RC414 increased cAMP levels, through the specific inhibition of the cAMP high affinity phosphodiesterase (IC50 = 1.73 +/- 0.35 microM). RC414 reduced [Ca2+]i transients and PKC activation induced by thrombin. In addition RC414 was able to increase nitric oxide formation involving the stimulation of constitutive nitric oxide synthase enzyme. In conclusion, RC414 exerts its powerful anti-platelet activity by increasing cAMP intracellular levels and nitric oxide formation.

Pyran derivatives. Part XXI. Antiproliferative and cytotoxic properties of novel N-substituted 4-aminocoumarins, their benzo-fused derivatives, and some related 2-aminochromones.

The N-substituted tricyclic 2-aminochromone derivatives 1a, 2a, and 2b were obtained by treating the corresponding (methylthio) or (methylsulfinyl) derivatives 10, 11, or 12, respectively, with an excess of the proper amines. Compound 2c was synthesized through the reaction of 2-naphthol with the ethyl N,N-diphenylmalonamate/POCl(3) reagent 14. The N-substituted 4-aminocoumarin bicyclic and tricyclic derivatives 5-8 were prepared by treating the corresponding chloro derivatives with the excess suitable amines. Compounds 1, 2, 5-8 were tested in vitro for their antiproliferative activity (DNA synthesis inhibition in Ehrlich cells) and cytotoxicity (MTT test in HeLa cells). The inhibitory properties of three selected compounds (5c, 5e, 7c) on protein and RNA syntheses in Ehrlich cells were also evaluated. Among the 27 compounds tested, 10 4-aminocoumarin derivatives (5-8) and two 2-aminochromone derivatives (1a and 2a) showed an appreciable antiproliferative activity (IC(50) range: 1.74-13.8 microM), whereas only four compounds 5-8 exhibited a comparable cytotoxic activity (IC(50) range: 4.95-12.9 microM).

Coumarin, chromone, and 4(3H)-pyrimidinone novel bicyclic and tricyclic derivatives as antiplatelet agents: synthesis, biological evaluation, and comparative molecular field analysis.

As a further part of our chemical and biological studies in this field, we describe the multistep preparations of the properly substituted 2-(1-piperazinyl)chromone 1b, 4-(1-piperazinyl)coumarins 5c-h, their linear benzo-fused analogues 4a,b and 8a,b, bicyclic (15e-g) and tricyclic (15h,i) fused derivatives of 6-(1-piperazinyl)pyrimidin-4(3H)-one, and of the 4H-pyrido[1,2-a]pyrimidine derivatives 9b,c. The in vitro evaluation of their inhibitory properties towards human platelet aggregation induced in platelet-rich plasma by ADP, collagen, or the Ca (2+)ionophore A23187 showed the high activity of compounds 5d-g and 15f,g,i, among which the coumarins 5g and 5d proved to be, in that order, the most effective in vitro antiplatelet agents until now synthesized by us. Thus, in order to consider also the 4-aminocoumarin structural class, we developed a new statistically significant 3-D QSAR model, more general than the one previously obtained, through a further CoMFA study based on the antiplatelet activity data and molecular steric and electrostatic potentials of both the previously studied and herein described compounds.