Design, synthesis, and biological characterization of potential antiatherogenic nitric oxide releasing tocopherol analogs

Design, Synthesis and Study of Nitrogen Monoxide Donors as Potent Hypolipidaemic and Anti-Inflammatory Agents

Inflammation and oxidative stress are involved in cardiovascular diseases. Nitrogen monoxide participates in the regulation of endothelial processes. Thus, derivatives of classic nonsteroidal anti-inflammatory drugs (NSAIDs), trolox or cinnamic acids esterified with 2-(nitrooxy)ethanol were designed and studied. It was found that the nitrogen monoxide (NO) releasing activity was comparable to that of S-nitroso-N-acetylpenicillamine. The nitrooxy derivatives decreased potently lipid indices in the plasma of hyperlipidaemic rats (30–85%). All compounds presented increased anti-inflammatory activity in vivo, inhibiting carrageenan-induced rat paw oedema as high as 76%, up to six times higher than that of the parent acids. Lipoxygenase inhibitory activity was significant for most of them, although the parent molecules exerted a minor effect (IC₅₀ > 0.2 mM). Those compounds incorporating an antioxidant structure inhibited rat microsomal membrane lipid peroxidation strongly and possessed radical scavenging activity. These results indicated that the described compounds could act at different targets in multifactorial diseases, further limiting the possible adverse effects of drug combinations.

Synthesis, structure, antioxidant activity, and water solubility of trolox ion conjugates

The interaction of trolox with ammonia, alkylamines of different classes, and amino derivatives of heterocyclic compounds, including nitroxyl radicals and alkaloids, led to the production of ammonium salts called ion conjugates (ICs). Five ICs were characterised by X-ray diffraction. This is the first time a wide range of ICs were made from trolox with amines, and ESI-MS data demonstrated they have the potential to generate pseudomolecular [(A⁻B⁺) + H]⁺ ions. For all obtained trolox ICs, a significant increase (1–3 orders of magnitude) in water solubility was achieved while retaining high antioxidant activity. ICs synthesised from two biologically active fragments may be used to create polyfunctional agents with varying solubility and bioavailability.

Design, synthesis, and pharmacological evaluation of novel hybrid compounds to treat sickle cell disease symptoms. part II: furoxan derivatives

Phthalimide derivatives containing furoxanyl subunits as nitric oxide (NO)-donors (3a-g) were designed, synthesized, and evaluated in vitro and in vivo for their potential uses in the oral treatment of sickle cell disease symptoms. All compounds (3a-g) demonstrated NO-donor properties at different levels. Moreover, compounds 3b and 3c demonstrated analgesic activity. Compound 3b was determined to be a promising drug candidate for the aforementioned uses, and it was further evaluated in K562 culture cells to determine its ability to increase levels of γ-globin expression. After 96 h at 5 μM, compound 3b was able to induce γ-globin expression by nearly three times. Mutagenic studies using micronucleus tests in peripheral blood cells of mice demonstrated that compound 3b reduces the mutagenic profile as compared with hydroxyurea. Compound 3b has emerged as a new leading drug candidate with multiple beneficial effects for the treatment of sickle cell disease symptoms and provides an alternative to hydroxyurea treatment.

6-Methylnitroarachidonate: a novel esterified nitroalkene that potently inhibits platelet aggregation and exerts cGMP-mediated vascular relaxation

Nitro-fatty acids represent endogenously occurring products of oxidant-induced nitration reactions. We have previously synthesized a mixture of four isomers of nitroarachidonic acid, a novel anti-inflammatory signaling mediator. In this study, we synthesized and chemically and biologically characterized for the first time an esterified nitroalkene derived from the nitration of methylarachidonate (AAMet): 6-methylnitroarachidonate (6-AAMetNO(2)). Synthesis was performed by reacting AAMet with sodium nitrite under acidic conditions. Analysis by mass spectrometry (positive-ion ESI-MS) showed an [M+H](+) ion of m/z 364, characteristic of AAMetNO(2). Fragmentation of this ion yielded a daughter ion at m/z 317, corresponding to the neutral loss of the nitro group ([M+H-HNO(2)](+)). Furthermore, IR signal at 1378 cm(-1) and NMR data confirmed the structure of a 6-nitro-positional isomer. This novel esterified nitroalkene was capable of promoting vascular protective actions including: (a) the induction of vasorelaxation via endothelium-independent mechanisms, associated with an increase in smooth muscle cell cGMP levels, and (b) a potent dose-dependent inhibition of human platelet aggregation. We postulate that 6-AAMetNO(2) could be a potential drug for the prevention of vascular and inflammatory diseases, and the presence of the methyl group may increase its pharmacological potential.

Second generation of alpha-tocopherol analogs-nitric oxide donors: Synthesis, physicochemical, and biological characterization

Synthesis, physicochemical, and biological characterization of a series of alpha-tocopherol mimetics with NO-releasing capacity are reported. The selected NO-donor moieties were nitrooxy and furoxan. All products were tested for their in vitro NO-releasing capacities, vasodilating properties and mammal cytotoxic activities. The lipophilic-hydrophilic balance of all products was also evaluated. A new hybrid furoxan, phenol derivative 17, possesses adequate profile of the studied properties.

Esterase-activated chromane–sydnonimine prodrug hybrids

The preparation and characterization of two vitamin E analogs-sydnonimine conjugates, delta-tocopheryloxycarbonyl-3-morpholinosydnonimine (2) and troloxoxycarbonyl-3-morpholinosydnonimine (3), in which the hydroxyl group of the tocopheryl moieties is linked via an enzymatically cleavable urethane group to the sydnone moiety is described. In the presence of porcine liver esterase, these tocopheryl-sydnonimine conjugates generated the expected antioxidant moieties, i.e., delta-tocopherol or Trolox, and were found to convert oxyhemoglobin to methemoglobin at 37 degrees C in 50 mM phosphate buffer at pH 7.4, thus providing evidence for nitric oxide release. Their potency as antioxidants was indirectly studied by associating the two products of the hydrolysis, SIN-1, and delta-tocopherol or Trolox. Our findings suggest that unlike the other members of the sydnonimine family these chromane-sydnonimine derivatives do not act as peroxynitrite donors, and require enzymatic bioactivation before nitric oxide or nitroxyl anion (NO(-)) can be released.

Nitric oxide/redox-based signalling as a therapeutic target for penile disorders

Oxidative and/or nitrosative stress is implicated in the pathogeneses of assorted penile disorders of clinical significance, notably erectile dysfunction, priapism and penile fibrosis. It is becoming increasingly recognised that the generation and activity of reactive oxygen and nitrogen species in the penis influence vascular homeostasis of this organ, with adverse effects exerted at cellular and molecular levels. Furthermore, these elements may interact with molecular signalling pathways operating in the penis, modulating their functional roles. This interaction in particular suggests that by accessing molecular targets associated with oxidative/nitrosative stress in the penis, new pharmacotherapeutic approaches may be developed to promote normal erectile ability and preserve erectile tissue health. This notion pertains to, but also extends beyond, interventions which predictably target components of the nitric oxide-based signal transduction pathway for the on-demand treatment of erectile dysfunction. The next line of pharmaceuticals for disorders of the penis, in general, may well spawn from an integrative understanding of the complex regulatory interactions influenced by, as well as influencing nitric oxide signalling in this organ.