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Introduction: Sex differences in inflammation are obvious and contribute to divergences in the incidence and severity of inflammation-related diseases that frequently preponderate in women. Lipid mediators (LMs), mainly produced by lipoxygenase (LOX) and cyclooxygenase (COX) pathways from polyunsaturated fatty acids (PUFAs), regulate all stages of inflammation. Experimental and clinical studies revealed sex divergences for selected LM pathways without covering the entire LM spectrum, and only few studies have addressed the respective role of sex hormones. Here, we performed the comprehensive LM profile analysis with inflammatory peritoneal exudates and plasma from male and female mice in zymosan-induced peritonitis to identify the potential sex differences in LM biosynthesis during the inflammatory response. We also addressed the impact of sex hormones by employing gonadectomy. Methods: Adult male and female CD1 mice received intraperitoneal injection of zymosan to induce peritonitis, a well-established experimental model of acute, self-resolving inflammation. Mice were gonadectomized 5 weeks prior to peritonitis induction. Peritoneal exudates and plasma were taken at 4 (peak of inflammation) and 24 h (onset of resolution) post zymosan and subjected to UPLC–MS-MS–based LM signature profiling; exudates were analyzed for LM biosynthetic proteins by Western blot; and plasma was analyzed for cytokines by ELISA. Results: Pro-inflammatory COX and 5-LOX products predominated in the peritoneum of males at 4 and 24 h post-zymosan, respectively, with slightly higher 12/15-LOX products in males after 24 h. Amounts of COX-2, 5-LOX/FLAP, and 15-LOX-1 were similar in exudates of males and females. In plasma of males, only moderate elevation of these LMs was apparent. At 4 h post-zymosan, gonadectomy strongly elevated 12/15-LOX products in the exudates of males, while in females, free PUFA and LOX products were rather impaired. In plasma, gonadectomy impaired most LMs in both sexes at 4 h with rather up-regulatory effects at 24 h. Finally, elevated 15-LOX-1 protein was evident in exudates of males at 24 h which was impaired by orchiectomy without the striking impact of gonadectomy on other enzymes in both sexes. Conclusions: Our results reveal obvious sex differences and roles of sex hormones in LM biosynthetic networks in acute self-resolving inflammation in mice, with several preponderances in males that appear under the control of androgens.

Prostaglandin E2 (PGE2) is an inflammatory mediator that plays a pivotal role in the evolvement and progression of inflammatory and tumor diseases.1The identification of novel inhibitors of eicosanoids biosynthesis with unexplored scaffolds is of great demand to develop a next generation of anti-inflammatory or anti-cancer drugs. Following a multidisciplinary protocol that involves virtual combinatorial screening, chemical synthesis, and validation of the biological activities we afforded to the identification of 1,2,4-oxadiazole-based hits, as a novel class of anti-inflammatory agents able to inhibit several enzymes involved in the progression of inflammation. 1,2,4-oxadiazoles represent a versatile “privileged scaffold” in drug discovery, due to the possibility of modifying and opportunely decorating the nucleus,2 and are never explored for their inhibitory activity on eicosanoid biosynthesis. This multidisciplinary scientific approach led to the identification of a multi-target inhibitor of cyclooxygenase-1 (COX-1), 5-lipoxygenase (5-LO) and microsomal prostaglandin E2 synthase-1 (mPGES-1). Moreover, in vivo studies on the disclosed hit demonstrate that it attenuates leukocytes migration in a model of zymosan-induced peritonitis and modulates the production of IL-1β and TNF-α. These promising outcomes pave the way toward a medicinal chemistry optimization campaign of the disclosed hit characterized by a promising and safer pharmacological profile.

Vitamin E exhibits pharmacological effects beyond established antioxidant activity suggesting involvement of unidentified mechanisms. Here, we characterize endogenously formed tocopherol carboxylates and the vitamin E mimetic garcinoic acid (GA) as activators of the peroxisome proliferator-activated receptor gamma (PPARg). Co-stimulation of PPARg with GA and the orthosteric agonist pioglitazone resulted in additive transcriptional activity. In line with this, the PPARg-GA complex adopted a fully active conformation and interestingly contained two bound GA molecules with one at an allosteric site. A co-regulator interaction scan demonstrated an unanticipated co-factor recruitment profile for GA-bound PPARg compared with canonical PPARg agonists and gene expression analysis revealed different effects of GA and pioglitazone on PPAR signaling in hepatocytes. These observations reveal allosteric mechanisms of PPARg modulation as an alternative avenue to PPARg targeting and suggest contributions of PPARg activation by a-13-tocopherolcarboxylate to the pharmacological effects of vitamin E.

Indirubin is a natural bis-indole alkaloid contained as active ingredient in the traditional Chinese remedy Danggui Longhui Wan. Indirubin and its 3′-oxime derivatives exhibit anti-cancer and anti-inflammatory properties and they inhibit glycogen synthase kinase (GSK)-3 in cell-free assays where 6-bromoindirubin-3′-oxime (6BIO) is among the most potent analogs. Here, we reveal 6-bromoindirubin-3′-glycerol-oxime ether (6BIGOE) as highly potent derivative able to inhibit pro-inflammatory cytokine, chemokine and prostaglandin (PG) release in human primary monocytes while increasing anti-inflammatory interleukin (IL)-10 levels. 6BIGOE suppressed lipopolysaccharide (LPS)-induced IL-1β and PGE2 release with IC50 of 0.008 and 0.02 µM, respectively, being ≥ 12-fold more potent than 6BIO. The effects of 6BIGOE are mediated via intracellular inhibition of GSK-3, where 6BIGOE again surpassed the effectiveness of 6BIO despite the higher potency of the latter in cell-free GSK-3 activity assays. Side-by-side comparison of 6BIGOE (0.1 µM) with the selective GSK-3 inhibitor SB216763 (5 µM) revealed congruent properties such as enrichment of β-catenin and suppression of cyclooxygenase (COX)-2 protein levels due to GSK–3 inhibition. Metabololipidomics using ultra-performance liquid chromatography-tandem mass spectrometry showed that 6BIGOE selectively decreases pro-inflammatory COX-derived product formation without marked modulation of other lipid mediators. In summary, 6BIGOE is a highly potent indirubin derivative in the cellular context that favorably modulates pro- and anti-inflammatory cytokines as well as COX-2-derived PG via interference with GSK-3. © 2020 Elsevier Inc.

A series of derivatives of the potent dual soluble epoxide hydrolase (sEH)/5-lipoxygenase-activating protein (FLAP) inhibitor diflapolin was designed, synthesized, and characterized by 1H NMR, 13C NMR, and elemental analysis. These novel compounds were biologically evaluated for their inhibitory activity against sEH and FLAP. Molecular modeling tools were applied to analyze structure-activity relationships (SAR) on both targets. Results show that even small modifications on the lead compound diflapolin markedly influence the inhibitory potential, especially on FLAP, suggesting very narrow SAR.

Aims: 5-Lipoxygenase (5-LO) is the key enzyme of leukotriene (LT) biosynthesis and is critically involved in a number of inflammatory diseases such as arthritis, gout, bronchial asthma, atherosclerosis, and cancer. Because 5-LO contains critical nucleophilic amino acids, which are sensitive to electrophilic modifications, we determined the consequences of a drug-mediated intracellular release of nitric oxide (NO) on 5-LO product formation by human granulocytes and on 5-LO-dependent pulmonary inflammation in vivo. Results: Clinically relevant concentrations of NO-releasing nonsteroidal anti-inflammatory drugs and other agents releasing NO intracellularly suppress 5-LO product synthesis in isolated human granulocytes via direct S-nitrosylation of 5-LO at the catalytically important cysteines 416 and 418. Furthermore, suppression of 5-LO product formation was observed in ionophore-stimulated human whole blood and in an animal model of pulmonary inflammation. Innovation: Here, we report for the first time that drugs releasing NO intracellularly are efficient 5-LO inhibitors in vitro and in vivo at least equivalent to approved 5-LO inhibitors. Conclusion: Our findings provide a novel mechanistic strategy for the development of a new class of drugs suppressing LT biosynthesis by site-directed nitrosylation. The results may also help to better understand the well-recognized anti-inflammatory clinically relevant actions of NO-releasing drugs. Furthermore, our study describes in detail a novel molecular mode of action of NO.

Sphingosine‐1‐phosphate (S1P) is involved in the regulation of important cellular processes, including immune‐cell trafficking and proliferation. Altered S1P signaling is strongly associated with inflammation, cancer progression, and atherosclerosis; however, the mechanisms underlying its pathophysiologic effects are only partially understood. This study evaluated the effects of S1P in vitro and in vivo on the biosynthesis of leukotrienes (LTs), which form a class of lipid mediators involved in the pathogenesis of inflammatory diseases. Here, we report for the first time that S1P potently suppresses LT biosynthesis in Ca2+‐ionophore-stimulated intact human neutrophils. S1P treatment resulted in intracellular Ca2+ mobilization, perinuclear translocation, and finally irreversible suicide inactivation of the LT biosynthesis key enzyme 5‐lipoxygenase (5‐LO). Agonist studies and S1P receptor mRNA expression analysis provided evidence for a S1P receptor 4-mediated effect, which was confirmed by a functional knockout of S1P4 in HL60 cells. Systemic administration of S1P in wild‐type mice decreased both macrophage and neutrophil migration in the lungs in response to LPS and significantly attenuated 5‐LO product formation, whereas these effects were abrogated in 5‐LO or S1P4 knockout mice. In summary, targeting the 5‐LO pathway is an important mechanism to explain S1P‐mediated pathophysiologic effects. Furthermore, agonism at S1P4 represents a novel effective strategy in pharmacotherapy of inflammation.

Among the pathways responsible for the development of inflammatory responses, the cyclooxygenase and lipoxygenase pathways are among the most important ones. Two key enzymes, namely, 5-LO and mPGES-1, are involved in the biosynthesis of leukotrienes and prostaglandins, respectively, which are considered attractive therapeutic targets, so their dual inhibition might be an effective strategy to control inflammatory deregulation. Several natural products have been identified as 5-LO inhibitors, with some also being dual 5-LO/mPGES-1 inhibitors. Here, some prenylated acetophenone dimers from Acronychia pedunculata have been identified for their dual inhibitory potency toward 5-LO and mPGES-1. To gain insight into the SAR of this family of natural products, the synthesis and biological evaluation of analogues are presented. The results show the ability of the natural and synthetic molecules to potently inhibit 5-LO and mPEGS-1 in vitro. The potency of the most active compound (10) has been evaluated in vivo in an acute inflammatory mouse model and displayed potent anti-inflammatory activity comparable in potency to the drug zileuton used as a positive control. © 2017 The American Chemical Society and American Society of Pharmacognosy.

Background and Purpose Leukotrienes (LTs) are inflammatory mediators produced via the 5-lipoxygenase (5-LOX) pathway and are linked to diverse disorders, including asthma, allergic rhinitis and cardiovascular diseases. We recently identified the benzimidazole derivative BRP-7 as chemotype for anti-LT agents by virtual screening targeting 5-LOX-activating protein (FLAP). Here, we aimed to reveal the in vitro and in vivo pharmacology of BRP-7 as an inhibitor of LT biosynthesis. Experimental Approach We analysed LT formation and performed mechanistic studies in human neutrophils and monocytes, in human whole blood (HWB) and in cell-free assays. The effectiveness of BRP-7 in vivo was evaluated in rat carrageenan-induced pleurisy and mouse zymosan-induced peritonitis. Key Results BRP-7 potently suppressed LT formation in neutrophils and monocytes and this was accompanied by impaired 5-LOX co-localization with FLAP. Neither the cellular viability nor the activity of 5-LOX in cell-free assays was affected by BRP-7, indicating that a functional FLAP is needed for BRP-7 to inhibit LTs, and FLAP bound to BRP-7 linked to a solid matrix. Compared with the FLAP inhibitor MK-886, BRP-7 did not significantly inhibit COX-1 or microsomal prostaglandin E2synthase-1, implying the selectivity of BRP-7 for FLAP. Finally, BRP-7 was effective in HWB and impaired inflammation in vivo, in rat pleurisy and mouse peritonitis, along with reducing LT levels. Conclusions and Implications BRP-7 potently suppresses LT biosynthesis by interacting with FLAP and exhibits anti-inflammatory effectiveness in vivo, with promising potential for further development. © 2014 The British Pharmacological Society.

The discovery of new active natural products is hampered by laborious purification processes that often end up to the re-isolation of known compounds. We demonstrate here that, spectral data reflecting concentration fluctuations of components can correlate statistically with measurable dose-dependent properties on the basis of a Heterocovariance approach deconvoluting the active components structure. Variance of extract constituents was achieved through statistically meaningful collections of plants from different families, genus, and species. This fluctuation was also obtained through the fractionation of a single plant extract by separation techniques. The NMR and HRMS spectra of the extracts and fractions were recorded, as well as their ability to inhibit tyrosinase or 5-lipoxygenase enzymes. Biological activity was statistically correlated with spectral data deciphering the active compounds through the Heterocovariance approach prior to any purification. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Canonical Wnt signaling is a highly conserved pathway with a prominent role in embryogenic development, adult tissue homeostasis, cell polarization, stem cell biology, cell differentiation, and proliferation. Furthermore, canonical Wnt signaling is of pivotal importance in the pathogenesis of a number of cancer types and crucially affects tumor initiation, cancer cell proliferation, cancer cell apoptosis, and metastasis. Reports over the last decade have provided strong evidence fora pathophysiological role of Wnt signaling in nonmalignant classical inflammatory and neurodegenerative diseases. Although, several agents suppressing the Wnt pathway at different levels have been identified, the development of clinically relevant Wnt-inhibiting agents remains challenging due to selectivity and toxicity issues. Several studies have shown that long-term administration of non-steroidal anti-inflammatory drugs protects against colon cancer and potentially other tumor types by interfering both with the COX and the Wnt pathway. Our own studies have shown that non-steroidal anti-inflammatory drugs suppress Wnt signaling by targeting the pro-inflammatory enzyme 5-lipoxygenase which is the key enzyme pathophysiologically involved in the synthesis of leukotrienes. Furthermore, we found a direct link between the 5-lipoxygenase and Wnt signaling pathways, which is essential for the maintenance of leukemic stem cells. Accordingly, genetic and pharmacological inhibition of 5-lipoxygenase led to an impairment of Wnt-dependent acute and chronic myeloid leukemic stem cells. We believe that 5-lipoxygenase inhibitors might represent a novel type of Wnt inhibitor activating a potentially naturally occurring novel mechanism of suppression of Wnt signaling that is non-toxic, at least in mice, and is potentially well tolerated in patients.

BACKGROUND AND PURPOSE: 1,4-Benzoquinones are well-known inhibitors of 5-lipoxygenase (5-LOX, the key enzyme in leukotriene biosynthesis), but the molecular mechanisms of 5-LOX inhibition are not completely understood. Here we investigated the molecular mode of action and the pharmacological profile of the novel 1,4-benzoquinone derivative 3-((decahydronaphthalen-6-yl)methyl)-2,5-dihydroxycyclohexa-2,5-diene-1,4-dione (RF-Id) in vitro and its effectiveness in vivo. EXPERIMENTAL APPROACH: Mechanistic investigations in cell-free assays using 5-LOX and other enzymes associated with eicosanoid biosynthesis were conducted, along with cell-based studies in human leukocytes and whole blood. Molecular docking of RF-Id into the 5-LOX structure was performed to illustrate molecular interference with 5-LOX. The effectiveness of RF-Id in vivo was also evaluated in two murine models of inflammation. KEY RESULTS: RF-Id consistently suppressed 5-LOX product synthesis in human leukocytes and human whole blood. RF-Id also blocked COX-2 activity but did not significantly inhibit COX-1, microsomal PGE2 synthase-1, cytosolic PLA2 or 12- and 15-LOX. Although RF-Id lacked radical scavenging activity, reducing conditions facilitated its inhibitory effect on 5-LOX whereas cell stress impaired its efficacy. The reduced hydroquinone form of RF-Id (RED-RF-Id) was a more potent inhibitor of 5-LOX as it had more bidirectional hydrogen bonds within the 5-LOX substrate binding site. Finally, RF-Id had marked anti-inflammatory effects in mice in vivo. CONCLUSIONS AND IMPLICATIONS: RF-Id represents a novel anti-inflammatory 1,4-benzoquinone that potently suppresses LT biosynthesis by direct inhibition of 5-LOX with effectiveness in vivo. Mechanistically, RF-Id inhibits 5-LOX in a non-redox manner by forming discrete molecular interactions within the active site of 5-LOX.

Leukotrienes (LTs) are pro-inflammatory mediators linked to a variety of diseases including asthma, allergic rhinitis, cardiovascular diseases and cancer. They are produced by 5-lipoxygenase (5-LO) aided by 5-LO-activating protein (FLAP). Inhibition of LTs is currently pursued as potential pharmacological strategy for treatment of inflammation. There are two major pharmacological strategies pursued in order to intervene with LTs: (I) antagonism of LTs receptors and (II) inhibition of 5-LO product (i.e., LTs and 5-H(p)ETE) biosynthesis. However, inhibition of LT biosynthesis may also be achieved by targeting FLAP that is currently considered a promising and clinically relevant target for pharmacological intervention with LT-related disorders. BRP-7, a novel benzimidazole derivative, has been reported to inhibit LT biosynthesis by virtual screening targeting FLAP based on a combined ligand- and structure-based pharmacophore model (Banoglu et al., 2012). Here, in view of the ability of BRP-7 to interfere with FLAP and the promising in vitro results, we have investigated its effects in two in vivo models of LT-related acute inflammation: rat carrageenan-induced pleurisy and mouse zymosan-induced peritonitis. BRP-7 (10 mg/kg i.p., 30 min before carrageenan) exerted anti-inflammatory effects in the rat pleurisy model. In particular, 4 h after pleurisy induction, BRP-7 significantly reduced the exudate volume and leukocyte number, as well as the production of LTB4 which is the main 5-LO metabolite in the pleural exudates. The anti-inflammatory effect of BRP-7 has been also evaluated in another well-recognized model of acute inflammation, the mouse zymosan-induced peritonitis. BRP-7 (20 mg/kg i.p., 30 min before zymosan injection) reduced the typical inflammatory responses evaluated as vascular permeability (measured at 30 min by the mean of Evans Blue bound to plasma proteins); neutrophil infiltration (measured at 4 h as cellular migration into the peritoneum) and myeloperoxidase activity (an indicator of polymorphonuclear leukocyte accumulation also measured at 4 h). Interestingly, the anti-inflammatory effectiveness of BRP-7 was accompanied by significant reduction of LTC4 levels, the main 5-LO metabolite in zymosan-induced peritonitis, implying that BRP-7 inhibits LT biosynthesis in vivo accompanying the anti-inflammatory effectiveness. In conclusion, our results demonstrate that BRP-7 represents a LT biosynthesis inhibitor targeting FLAP with a promising pharmacological profile as anti-inflammatory drug. Banoglu et al. (2012). Bioorg Med Chem 2, 3728-41

Leukotrienes (LTs) are lipid mediators implicated in inflammatory and autoimmune diseases, often characterized by a sex- bias in the incidence (e.g., asthma). LTs derive from arachidonic acid through the action of 5-lipoxygenase (5-LO), which is a soluble protein translocating to perinuclear membranes after activation. We have previously shown sex-differences in LT formation in human whole blood and leukocytes, due to down-regulation of 5-LO product formation by androgens. Here we show that LT synthesis is sex-biased in vivo , in a model of zymosan-induced peritonitis. After intraperitoneal injection of zymosan in mice, an immediate production of LTs was observed within 30 min, which was significantly higher in female then in male mice (about two times). These effects were followed by the recruitment of neutrophils into the peritoneal cavity, and both infiltrating cell numbers and myeloperoxidase activity (marker for neutrophils) were significantly higher in females than in males. Interestingly, orchidectomy of male mice resulted in a significant increase of LT levels in the peritoneal exudates, while a decrease of LTs was observed in ovariectomized female mice, thus suggesting significant effects of both male and female sex hormones. Mechanistically, we observed that in vitro stimulation of resident peritoneal macrophages from female mice induced higher LTC 4 formation as compared to males, which was not due to different AA release or 5-LO protein expression, but was accompanied by a different 5-LO subcellular localization. Taking together, we here demonstrate that LT biosynthesis is sex-biased in vivo in mouse zymosan-induced peritonitis, seemingly related to a different activation status of 5-LO in peritoneal macrophages, with profound consequences on the development of the inflammatory reaction. These data further support the evaluation of a gender-tailored therapy with anti-LTs

BACKGROUND AND PURPOSE:Leukotrienes (LTs) are pro-inflammatory mediators produced by 5-lipoxygenase (5-LO). Currently available 5-LO inhibitors either lack efficacy or are toxic and novel approaches are required to establish a successful anti-LT therapy. Here we provide a detailed evaluation of the effectiveness of the plant-derived alkaloid tryptanthrin as an inhibitor of LT biosynthesis. EXPERIMENTAL APPROACH: We analysed LT formation and performed mechanistic studies in human neutrophils stimulated with pathophysiologically relevant stimuli (LPS and formyl peptide), as well as in cell-free assays (neutrophil homogenates or recombinant human 5-LO) and in human whole blood. The in vivo effectiveness of tryptanthrin was evaluated in the rat model of carrageenan-induced pleurisy. KEY RESULTS: Tryptanthrin potently reduced LT-formation in human neutrophils (IC(50) = 0.6µM). However, tryptanthrin is not a redox-active compound and did not directly interfere with 5-LO activity in cell-free assays. Similarly, tryptanthrin did not inhibit the release of arachidonic acid, the activation of MAPKs, or the increase in [Ca(2+) ](i) , but it modified the subcellular localization of 5-LO. Moreover, tryptanthrin potently suppressed LT formation in human whole blood (IC(50) = 10µM) and reduced LTB(4) levels in the rat pleurisy model after a single oral dose of 10mg·kg(-1) . CONCLUSIONS AND IMPLICATIONS: Our data reveal that tryptanthrin is a potent natural inhibitor of cellular LT biosynthesis with proven efficacy in whole blood and is effective in vivo after oral administration. Its unique pharmacological profile supports further analysis to exploit its pharmacological potential.

BACKGROUND AND PURPOSE: Frankincense, the gum resin derived from Boswellia species, showed anti-inflammatory efficacy in animal models and in pilot clinical studies. Boswellic acids (BAs) are assumed to be responsible for these effects but their anti-inflammatory efficacy in vivo and their molecular modes of action are incompletely understood. EXPERIMENTAL APPROACH: A protein fishing approach using immobilized BA and surface plasmon resonance (SPR) spectroscopy were used to reveal microsomal prostaglandin E(2) synthase-1 (mPGES1) as a BA-interacting protein. Cell-free and cell-based assays were applied to confirm the functional interference of BAs with mPGES1. Carrageenan-induced mouse paw oedema and rat pleurisy models were utilized to demonstrate the efficacy of defined BAs in vivo. KEY RESULTS: Human mPGES1 from A549 cells or in vitro-translated human enzyme selectively bound to BA affinity matrices and SPR spectroscopy confirmed these interactions. BAs reversibly suppressed the transformation of prostaglandin (PG)H(2) to PGE(2) mediated by mPGES1 (IC(50) = 3-10 µM). Also, in intact A549 cells, BAs selectively inhibited PGE(2) generation and, in human whole blood, β-BA reduced lipopolysaccharide-induced PGE(2) biosynthesis without affecting formation of the COX-derived metabolites 6-keto PGF(1α) and thromboxane B(2) . Intraperitoneal or oral administration of β-BA (1 mg·kg(-1) ) suppressed rat pleurisy, accompanied by impaired levels of PGE(2) and β-BA (1 mg·kg(-1) , given i.p.) also reduced mouse paw oedema, both induced by carrageenan. CONCLUSIONS AND IMPLICATIONS: Suppression of PGE(2) formation by BAs via interference with mPGES1 contribute to the anti-inflammatory effectiveness of BAs and of frankincense, and may constitute a biochemical basis for their anti-inflammatory properties.

The aim of this study was to investigate the phytochemical profile of the methanol extract of the aerial parts of Sedum sediforme and to identify its secondary metabolites. By means of chromatographic separation and enrichment of compounds, HPLC-ESI-MS, HRMS, 1D-, 2D-NMR and/or comparison with reference compounds, three triterpenes, two sterols, ten flavonoids and twelve phenolic compounds were identified, together with two new compounds, i.e. (2R, 3R)-5,7-dihydroxy-2,3-dimethyl-4-chromanone-7-O-b-D-glucoside (27) and butan-2-O-rutinoside (28). Out of the 29 identified secondary metabolites, 18 are described as ingredients of S. Sediforme herein for the first time. Furthermore, myricitrin, one of the major constituents, was tested for its ability to inhibit different enzymes within the arachidonic acid cascade in order to determine its anti-inflammatory properties. Whereas there was only either weak or no inhibition of the microsomal prostaglandin E2 synthase-1 (mPGES-1) and the soluble epoxide hydrolase (sEH), myricitrin showed strong inhibition of 5-lipoxygenase (5-LO), with an IC50 of 7.8 0.2 M.

Myrtucommulone a nonprenylated acylphloroglucinol contained in the leaves of myrtle (Myrtus communis), has been reported to suppress the biosynthesis of eicosanoids by inhibition of 5-lipoxygenase and cyclooxygenase-1 in vitro and to inhibit the release of elastase and the formation of reactive oxygen species in activated polymorphonuclear leukocytes. Here, in view of the ability of MC to suppress typical proinflammatory cellular responses in vitro, we have investigated the effects of MC in in vivo models of inflammation. MC was administered to mice intraperitoneally, and paw edema and pleurisy were induced by the subplantar and intrapleural injection of carrageenan, respectively. MC (0.5, 1.5, and 4.5 mg/kg i.p.) reduced the development of mouse carrageenan-induced paw edema in a dose-dependent manner. Moreover, MC (4.5 mg/kg i.p. 30 min before and after carrageenan) exerted anti-inflammatory effects in the pleurisy model. In particular, 4 h after carrageenan injection in the pleurisy model, MC reduced: 1) the exudate volume and leukocyte numbers; 2) lung injury (histological analysis) and neutrophil infiltration (myeloperoxidase activity); 3) the lung intercellular adhesion molecule-1 and P-selectin immunohistochemical localization; 4) the cytokine levels (tumor necrosis factor-α and interleukin-1 β in the pleural exudate and their immunohistochemical localization in the lung; 5) the leukotriene B 4, but not prostaglandin E2, levels in the pleural exudates; and 6) lung peroxidation (thiobarbituric acid-reactant substance) and nitrotyrosine and poly (ADP-ribose) immunostaining. In conclusion, our results demonstrate that MC exerts potent anti-inflammatory effects in vivo and offer a novel therapeutic approach for the management of acute inflammation. Copyright © 2009 by The American Society for Pharmacology and Experimental Therapeutics.

The enzymes 5-lipoxygenase (5-LO) and glycogen synthase kinase (GSK)-3 represent promising drug targets in inflammation. We made use of the bisindole core of indirubin, present in GSK-3 inhibitors, to innovatively target 5-LO at the ATP-binding site for the design of dual 5-LO/GSK-3 inhibitors. Evaluation of substituted indirubin derivatives led to the identification of (3Z)-6-bromo-3-[(3E)-3-hydroxyiminoindolin-2-ylidene]indolin-2-one (15) as a potent, direct, and reversible 5-LO inhibitor (IC50 = 1.5 μM), with comparable cellular effectiveness on 5-LO and GSK-3. Together, we present indirubins as novel chemotypes for the development of 5-LO inhibitors, the interference with the ATP-binding site as a novel strategy for 5-LO targeting, and dual 5-LO/GSK-3 inhibition as an unconventional and promising concept for anti-inflammatory intervention. © 2014 American Chemical Society.

The dialdehydes oleacein (2) and oleocanthal (4) are closely related to oleuropein (1) and ligstroside (3), the two latter compounds being abundant iridoids of Olea europaea. By exploiting oleuropein isolated from the plant leaf extract, an efficient procedure has been developed for a one-step semisynthesis of oleacein under Krapcho decarbomethoxylation conditions. Highlighted is the fact that 5-lipoxygenase is a direct target for oleacein with an inhibitory potential (IC50: 2 μM) more potent than oleocanthal (4) and oleuropein (1). This enzyme catalyzes the initial steps in the biosynthesis of pro-inflammatory leukotrienes. Taken together, the methodology presented here offers an alternative solution to isolation or total synthesis for the procurement of oleacein, thus facilitating the further development as a potential anti-inflammatory agent. © 2014 The American Chemical Society and American Society of Pharmacognosy.