Synthesis of some novel organic nitrates and comparative in vitro study of their vasodilator profile.

Synthesis and structural characterization of the 4-phenylbutane-1,2-diyl dinitrate and of the erythro and threo diastereoisomers of 4-phenylbutane-1,2,3-triyl trinitrate as well as the HPLC chiral separation of the corresponding racemic mixtures are reported. Vasodilator activity of the single enantiomers of these products, of 4-phenylbutyl nitrate, and of the previously described phenylpropyl analogues were assessed on rat aorta strips precontracted with phenylephrine. The compounds were able to relax the contracted tissue in a concentration dependent manner. In the couples of antipodes, a complete lack of enantioselectivity was observed as far as the vasodilator potency is concerned. The concentration response curves of the products, with the exception of those of all the trinitrooxy substituted models, were rightward shifted in the presence of ALDH-2 inhibitors. Mono and dinitrates, but not trinitrates, displayed in vitro cross-tolerance with GTN. This new series of nitric acid esters is an interesting tool that can help to shed light on the unresolved puzzle of nitrate pharmacology. Selected members are worthy of additional study as potential drugs.

A novel hybrid aspirin-NO-releasing compound inhibits TNFalpha release from LPS-activated human monocytes and macrophages.

BACKGROUND: The cytoprotective nature of nitric oxide (NO) led to development of NO-aspirins in the hope of overcoming the gastric side-effects of aspirin. However, the NO moiety gives these hybrids potential for actions further to their aspirin-mediated anti-platelet and anti-inflammatory effects. Having previously shown that novel NO-aspirin hybrids containing a furoxan NO-releasing group have potent anti-platelet effects, here we investigate their anti-inflammatory properties. Here we examine their effects upon TNFalpha release from lipopolysaccharide (LPS)-stimulated human monocytes and monocyte-derived macrophages and investigate a potential mechanism of action through effects on LPS-stimulated nuclear factor-kappa B (NF-kappaB) activation. METHODS: Peripheral venous blood was drawn from the antecubital fossa of human volunteers. Mononuclear cells were isolated and cultured. The resultant differentiated macrophages were treated with pharmacologically relevant concentrations of either a furoxan-aspirin (B8, B7; 10 muM), their respective furazan NO-free counterparts (B16, B15; 10 muM), aspirin (10 muM), existing nitroaspirin (NCX4016; 10 muM), an NO donor (DEA/NO; 10 muM) or dexamethasone (1 muM), in the presence and absence of LPS (10 ng/ml; 4 h). Parallel experiments were conducted on undifferentiated fresh monocytes. Supernatants were assessed by specific ELISA for TNFalpha release and by lactate dehydrogenase (LDH) assay for cell necrosis. To assess NF-kappaB activation, the effects of the compounds on the loss of cytoplasmic inhibitor of NF-kappaB, IkappaBalpha (assessed by western blotting) and nuclear localisation (assessed by immunofluorescence) of the p65 subunit of NF-kappaB were determined. RESULTS: B8 significantly reduced TNFalpha release from LPS-treated macrophages to 36 +/- 10% of the LPS control. B8 and B16 significantly inhibited monocyte TNFalpha release to 28 +/- 5, and 49 +/- 9% of control, respectively. The B8 effect was equivalent in magnitude to that of dexamethasone, but was not shared by 10 muM DEA/NO, B7, the furazans, aspirin or NCX4016. LDH assessment revealed none of the treatments caused significant cell lysis. LPS stimulated loss of cytoplasmic IkappaBalpha and nuclear translocation of the p65 NF-kappaB subunit was inhibited by the active NO-furoxans. CONCLUSION: Here we show that furoxan-aspirin, B8, significantly reduces TNFalpha release from both monocytes and macrophages and suggest that inhibition of NF-kappaB activation is a likely mechanism for the effect. This anti-inflammatory action highlights a further therapeutic potential of drugs of this class.