Eicosanoid nomenclature

5-(4H)-Oxazolones and Their Benzamides as Potential Bioactive Small Molecules

The five membered heterocyclic oxazole group plays an important role in drug discovery. Oxazolones present a wide range of biological activities. In this article the synthesis of 4-substituted-2-phenyloxazol-5(4H)-ones from the appropriate substituted aldehydes via an Erlenmeyer–Plochl reaction is reported. Subsequently, the corresponding benzamides were produced via a nucleophilic attack of a secondary amine on the oxazolone ring applying microwave irradiation. The compounds are obtained in good yields up to 94% and their structures were confirmed using IR, ¹H-NMR, ¹³C-NMR and LC/MS data. The in vitro anti-lipid peroxidation activity and inhibitory activity against lipoxygenase and trypsin induced proteolysis of the novel derivatives were studied. Inhibition of carrageenin-induced paw edema (CPE) and nociception was also determined for compounds 4a and 4c. Oxazolones 2a and 2c strongly inhibit lipid peroxidation, followed by oxazolones 2b and 2d with an average inhibition of 86.5%. The most potent lipoxygenase inhibitor was the bisbenzamide derivative 4c, with IC₅₀ 41 μM. The benzamides 3c, 4a–4e and 5c were strong inhibitors of proteolysis. The replacement of the thienyl moiety by a phenyl group does not favor the protection. Compound 4c inhibited nociception higher than 4a. The replacement of thienyl groups by phenyl ring led to reduced biological activity. Docking studies of the most potent LOX inhibitor highlight interactions through allosteric mechanism. All the potent derivatives present good oral bioavailability.

2-Arylidene-1-indandiones as Pleiotropic Agents with Antioxidant and Inhibitory Enzymes Activities

Indandiones are a relatively new group of compounds presenting a wide range of biological activities. The synthesis of these compounds was performed via a Knoevenagel reaction between an aldehyde and 1,3-indandione and were obtained with a yield up to 54%. IR, 1H-Nucleic Magnetic Resonance (NMR), 13C-NMR, LC/MS ESI+ and elemental analysis were used for the confirmation of the structures of the novel derivatives. Lipophilicity values of compounds were calculated theoretically and experimentally by reversed chromatography method as values RM. The novel derivatives were studied through in vitro and in vivo experiments for their activity as anti-inflammatory and antioxidant agents and as inhibitors of lipoxygenase, trypsin, and thrombin. The inhibition of the carrageenin-induced paw edema (CPE) was also determined for representative structures. In the above series of experiments, we find that all the compounds showed moderate to satisfying interaction with the stable DPPH free radical in relation to the concentration and the time 2-arylidene-1-indandione (10) was the strongest. We observed moderate or very low antioxidant activities for selected compounds in the decolorization assay with ABTS+•. Most of the compounds showed high anti-lipid peroxidation of linoleic acid induced by AAPH.2-arylidene-1-indandione (7) showed a strongly inhibited soybean LOX. Only 2-arylidene-1-indandione (3) showed moderate scavenging activity of superoxide anion, whereas 2-arylidene-1-indandione (8) and 2-arylidene-1-indandione (9) showed very strong inhibition on proteolysis. 2-arylidene-1-indandione (8) highly inhibited serine protease thrombin. 2-arylidene-1-indandiones (7, 8 and 9) can be used as lead multifunctional molecules. The compounds were active for the inhibition of the CPE (30-57%) with 2-arylidene-1-indandione (1) being the most potent (57%). According to the predicted results a great number of the derivatives can cross the Blood-Brain Barrier (BBB), act in CNS and easily transported, diffused, and absorbed. Efforts are conducted a) to correlate quantitatively the in vitro/in vivo results with the most important physicochemical properties of the structural components of the molecules and b) to clarify the correlation of actions among them to propose a possible mechanism of action. Hydration energy as EHYDR and highest occupied molecular orbital (HOMO) better describe their antioxidant profile whereas the lipophilicity as RM values governs the in vivo anti-inflammatory activity. Docking studies are performed and showed that soybean LOX oxidation was prevented by blocking into the hydrophobic domain the substrates to the active site.

Naturally occurring monoepoxides of eicosapentaenoic acid and docosahexaenoic acid are bioactive antihyperalgesic lipids

Beneficial physiological effects of long-chain n-3 polyunsaturated fatty acids are widely accepted but the mechanism(s) by which these fatty acids act remains unclear. Herein, we report the presence, distribution, and regulation of the levels of n-3 epoxy-fatty acids by soluble epoxide hydrolase (sEH) and a direct antinociceptive role of n-3 epoxy-fatty acids, specifically those originating from docosahexaenoic acid (DHA). The monoepoxides of the C18:1 to C22:6 fatty acids in both the n-6 and n-3 series were prepared and the individual regioisomers purified. The kinetic constants of the hydrolysis of the pure regioisomers by sEH were measured. Surprisingly, the best substrates are the mid-chain DHA epoxides. We also demonstrate that the DHA epoxides are present in considerable amounts in the rat central nervous system. Furthermore, using an animal model of pain associated with inflammation, we show that DHA epoxides, but neither the parent fatty acid nor the corresponding diols, selectively modulate nociceptive pathophysiology. Our findings support an important function of epoxy-fatty acids in the n-3 series in modulating nociceptive signaling. Consequently, the DHA and eicosapentaenoic acid epoxides may be responsible for some of the beneficial effects associated with dietary n-3 fatty acid intake.

The Basic Science of Wound Healing

Understanding wound healing today involves much more than simply stating that there are three phases: "inflammation, proliferation, and maturation." Wound healing is a complex series of reactions and interactions among cells and "mediators." Each year, new mediators are discovered and our understanding of inflammatory mediators and cellular interactions grows. This article will attempt to provide a concise report of the current literature on wound healing by first reviewing the phases of wound healing followed by "the players" of wound healing: inflammatory mediators (cytokines, growth factors, proteases, eicosanoids, kinins, and more), nitric oxide, and the cellular elements. The discussion will end with a pictorial essay summarizing the wound-healing process.

Dual acting anti-inflammatory drugs: a reappraisal

Rheumatic diseases are the most prevalent causes of disability in western countries, and non-steroidal anti-inflammatory drugs (NSAIDs) are still the most commonly used remedies. However, NSAIDs cause several serious adverse effects, the most important being from gastric injury to gastric ulceration and renal damage. Attempts to develop non-steroidal anti-inflammatory remedies devoid of these shortcomings-especially gastrointestinal toxicity-have followed several strategies. Non-steroidal anti-inflammatory drugs have, therefore, been associated with gastroprotective agents that counteract the damaging effects of prostaglandin synthesis suppression; however, a combination therapy introduces other problems of pharmacokinetics, toxicity, and patient's compliance. More recently, incorporation of a nitric oxide (NO)-generating moiety into the molecule of several NSAIDs was shown to greatly attenuate their ulcerogenic activity; however, several findings suggest a possible involvement of NO in the pathogenesis of arthritis and subsequent tissue destruction. A most promising approach seemed to be the preparation of novel NSAIDs, targeted at the inducible isoform of prostaglandin synthase (COX-2); they appear to be devoid of gastrointestinal toxicity, in that they spare mucosal prostaglandin synthesis. However, a number of recent studies have raised serious questions about the two central tenets that support this approach, namely that the prostaglandins that mediate inflammation and pain are produced solely via COX-2 and that the prostaglandins that are important in gastrointestinal and renal function are produced solely via COX-1. So, a growing body of evidence shows that COX-2 (not only COX-1) also plays a physiological role in several body functions and that, conversely, COX-1 (not only COX-2) may also be induced at sites of inflammation. More recent and puzzling data shows that COX-2 is induced during the resolution of an inflammatory response, and at this point it produces anti-inflammatory (PGD2 and PGF2alpha), but not proinflammatory (PGE2) prostaglandins; inhibition of COX-2 at this point thus results in persistence of the inflammation. Moreover, COX-2 selective NSAIDs have lost the cardiovascular protective effects of non-selective NSAIDs, effects which are mediated through COX-1 inhibition (in addition, COX-2 has a role in sustaining vascular prostacyclin production). The generation of other very important products of the arachidonic acid cascade (besides cyclooxygenase-produced metabolites) is inhibited neither by non-selective nor by COX-2 selective NSAIDs. The products generated by the 5-lipoxygenase pathway (leukotrienes) are particularly important in inflammation; indeed, leukotrienes increase microvascular permeability and are potent chemotactic agents. Moreover, inhibition of 5-lipoxygenase indirectly reduces the expression of TNF-alpha (a cytokine that plays a key role in inflammation). These data and considerations explain the efforts to obtain drugs able to inhibit both 5-lipoxygenase and cyclooxygenases, the so-called dual acting anti-inflammatory drugs. Such compounds retain the activity of classical NSAIDs, while avoiding their main drawbacks, in that curtailed production of gastroprotective prostaglandins is associated with a concurrent curtailed production of the gastro-damaging and bronchoconstrictive leukotrienes. Moreover, thanks to their mechanism of action, dual acting anti-inflammatory drugs could not merely alleviate symptoms of rheumatic diseases, but might also satisfy, at least in part, the criteria of a more definitive treatment. Indeed, leukotrienes are pro-inflammatory, increase microvascular permeability, are potent chemotactic agents and attract eosinophils, neutrophils and monocytes into the synovium.

"Enzymatic" lipid peroxidation: reactions of mammalian lipoxygenases

Lipoxygenase is a dioxygenase which incorporates one molecule of oxygen at a certain position of unsaturated fatty acids such as arachidonic and linolenic acids. The enzymatic oxygenation of unsaturated fatty acids is stereospecific concomitant with a stereoselective abstraction of hydrogen atom. Fatty acid cyclooxygenase is an atypical lipoxygenase incorporating two molecules of oxygen, and initiates the biosynthesis of prostaglandins and thromboxanes. Arachidonate 5-lipoxygenase is responsible for the leukotriene synthesis. No such bioactive compound has been found as a metabolite of the 12- and 15-lipoxygenase pathways, and their physiological roles are still unclarified. These enzymes have been purified, and their molecular and catalytic properties have been investigated. Their cDNA clones have been isolated, and their nucleotide sequences have been determined deducing the primary structures of the enzymes.