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c-Jun N-terminal kinases (JNKs) are involved in the myocardial and aortic remodeling, increased arterial tone, and arterial blood pressure elevation associated with hypertension. The aim of the present study was to investigate the antihypertensive effect of a new JNK inhibitor, 1H-indeno[1,2-b]quinoxalin-11-one oxime sodium salt (IQ-1S), on spontaneously hypertensive rats (SHRs). Experiments were performed using normotensive Wistar-Kyoto (WKY) rats and SHRs. Experimental groups of SHRs received IQ-1S intragastrically for 6 weeks in daily doses of 5 and 50 mg/kg; experimental groups of WKY rats received 50 mg/kg IQ-1S according to the same regimen. The IQ-1S administration regimen induced decreases in systolic blood pressure, mean arterial blood pressure, total peripheral resistance, blood viscosity, hematocrit, myocardial cell cross-sectional area, and aortic wall thickness in SHRs vs untreated SHRs. There were no significant differences in systolic blood pressure values between the control and experimental groups of WKY rats during the treatment period. A concentration-dependent decrease in the tone of carotid arterial rings isolated from SHRs was observed after JNK inhibitor application in vitro. Application of the JNK inhibitor diminished endothelin-1 secretion by human umbilical vein endothelial cells in vitro. The main mechanisms of the antihypertensive effect of IQ-1S included the attenuation of blood viscosity due to decreased hematocrit, a vasodilatory effect on arterial smooth muscle cells, and a decrease in endothelin-1 production by endothelial cells.

Human neutrophil elastase (HNE) is involved in a number of essential physiological processes and has been identified as a potential therapeutic target for treating acute and chronic lung injury. Nevertheless, only one drug, Sivelestat, has been approved for clinical use and just in Japan and the Republic of Korea. Thus, there is an urgent need for the development of low-molecular-weight synthetic HNE inhibitors, and we have developed a wide variety of HNE inhibitors with various chemical scaffolds. We hypothesized that substitution of the active fragment of Sivelestat into these HNE inhibitor scaffolds could modulate their inhibitory activity, potentially resulting in higher efficacy and/or improved chemical stability. Here, we report the synthesis, biological evaluation, and molecular modeling studies of novel compounds substituted with the 4-(sulfamoyl)phenyl pivalate fragment necessary for Sivelestat activity. Many of these compounds were potent HNE inhibitors with activity in the nanomolar range (IC 50 = 19-30 nM for compounds 3a , 3b , 3f , 3g , and 9a ), confirming that the 4-(sulfamoyl)phenyl pivalate fragment could substitute for the N-CO group at position 1 and offer a different point of attack for Ser195. Results of molecular docking of the these pivaloyl-containing compounds into the HNE binding site supported the mechanism of inhibitory activity involving a nucleophilic attack of Ser195 from the catalytic triad onto the pivaloyl carbonyl group. Furthermore, some compounds (e.g., 3a and 3f ) had a relatively good stability in aqueous buffer (t 1/2 > 9 h). Thus, this novel approach led to the identification of a number of potent HNE inhibitors that could be used as leads for the further development of new therapeutics., (Copyright © 2020 Crocetti, Giovannoni, Cantini, Guerrini, Vergelli, Schepetkin, Khlebnikov and Quinn.)

Rheumatoid arthritis (RA) is a chronic autoimmune disease involving joint and bone damage that is mediated in part by proteases and cytokines produced by synovial macrophages and fibroblast-like synoviocytes (FLS). Although current biological therapeutic strategies for RA have been effective in many cases, new classes of therapeutics are needed. We investigated anti-inflammatory properties of the natural alkaloid tryptanthrin (TRYP) and its synthetic derivative tryptanthrin-6-oxime (TRYP-Ox). Both TRYP and TRYP-Ox inhibited matrix metalloproteinase (MMP)-3 gene expression in interleukin (IL)-1β-stimulated primary human FLS, as well as IL-1β-induced secretion of MMP-1/3 by FLS and synovial SW982 cells and IL-6 by FLS, SW982 cells, human umbilical vein endothelial cells (HUVECs), and monocytic THP-1 cells, although TRYP-Ox was generally more effective and had no cytotoxicity in vitro . Evaluation of the therapeutic potential of TRYP and TRYP-Ox in vivo in murine arthritis models showed that both compounds significantly attenuated the development of collagen-induced arthritis (CIA) and collagen-antibody-induced arthritis (CAIA), with comparable efficacy. Collagen II (CII)-specific antibody levels were similarly reduced in TRYP- and TRYP-Ox-treated CIA mice. TRYP and TRYP-Ox also suppressed proinflammatory cytokine production by lymph node cells from CIA mice, with TRYP-Ox being more effective in inhibiting IL-17A, granulocyte-macrophage colony-stimulating factor (GM-CSF), and receptor activator of nuclear factor-κB ligand (RANKL). Thus, even though TRYP-Ox generally had a better in vitro profile, possibly due to its ability to inhibit c-Jun N-terminal kinase (JNK), both TRYP and TRYP-Ox were equally effective in inhibiting the clinical symptoms and damage associated with RA. Overall, TRYP and/or TRYP-Ox may represent potential new directions for the pursuit of novel treatments for RA., (Copyright © 2020 Kirpotina, Schepetkin, Hammaker, Kuhs, Khlebnikov and Quinn.)

The development of new advances in understanding the role of neutrophils in inflammation requires effective procedures for isolating and purifying neutrophils. Methods for isolating human neutrophils are fairly standard, and some are covered in other chapters of this volume and previous editions. However, procedures for isolating neutrophils from nonhuman species used to model human diseases vary from those used in isolating human neutrophils and are not as well developed. Since neutrophils are highly reactive and sensitive to small perturbations, the methods of isolation are important to avoid isolation technique-induced alterations in cell function. We present methods here for reproducibly isolating highly purified neutrophils from large animal models (bovine, equine, ovine), small animal models (murine and rabbit), and nonhuman primates (cynomolgus macaques) and describe optimized details for obtaining the highest cell purity, yield, and viability.

Cell division cycle 25 (Cdc25) and mitogen-activated protein kinase kinase 7 (MKK7) are enzymes involved in intracellular signaling but can also contribute to tumorigenesis. We synthesized and characterized the biological activity of 1,4-naphthoquinones structurally similar to reported Cdc25 and(or) MKK7 inhibitors with anticancer activity. Compound 7 (3-[(1,4-dioxonaphthalen-2-yl)sulfanyl]propanoic acid) exhibited high binding affinity for MKK7 (K d  = 230 nM), which was greater than the affinity of NSC 95397 (K d  = 1.1 μM). Although plumbagin had a lower binding affinity for MKK7, this compound and sulfur-containing derivatives 4 and 6-8 were potent inhibitors of Cdc25A and Cdc25B. Derivative 22e containing a phenylamino side chain was selective for MKK7 versus MKK4 and Cdc25 A/B, and its isomer 22f was a selective inhibitor of Cdc25 A/B. Docking studies performed on several naphthoquinones highlighted interesting aspects concerning the molecule orientation and hydrogen bonding interactions, which could help to explain the activity of the compounds toward MKK7 and Cdc25B. The most potent naphthoquinone-based inhibitors of MKK7 and/or Cdc25 A/B were also screened for their cytotoxicity against nine cancer cell lines and primary human mononuclear cells, and a correlation was found between Cdc25 A/B inhibitory activity and cytotoxicity of the compounds. Quantum chemical calculations using BP86 and ωB97X-D3 functionals were performed on 20 naphthoquinone derivatives to obtain a set of molecular electronic properties and to correlate these properties with cytotoxic activities. Systematic theoretical DFT calculations with subsequent correlation analysis indicated that energy of the lowest unoccupied molecular orbital E(LUMO), vertical electron affinity (VEA), and reactivity index ω of these molecules were important characteristics related to their cytotoxicity. The reactivity index ω was also a key characteristic related to Cdc25 A/B phosphatase inhibitory activity. Thus, 1,4-naphthoquinones displaying sulfur-containing and phenylamino side chains with additional polar groups could be successfully utilized for further development of efficacious Cdc25 A/B and MKK7 inhibitors with anticancer activity., (Copyright © 2019 Elsevier Masson SAS. All rights reserved.)

c-Jun N-terminal kinases (JNKs) play a central role in many physiologic and pathologic processes. We synthesized novel 11H-indeno[1,2-b]quinoxalin-11-one oxime analogs and tryptanthrin-6-oxime (indolo[2,1-b]quinazoline-6,12-dion-6-oxime) and evaluated their effects on JNK activity. Several compounds exhibited sub-micromolar JNK binding affinity and were selective for JNK1/JNK3 versus JNK2. The most potent compounds were 10c (11H-indeno[1,2-b]quinoxalin-11-one O-(O-ethylcarboxymethyl) oxime) and tryptanthrin-6-oxime, which had dissociation constants (K d ) for JNK1 and JNK3 of 22 and 76 nM and 150 and 275 nM, respectively. Molecular modeling suggested a mode of binding interaction at the JNK catalytic site and that the selected oxime derivatives were potentially competitive JNK inhibitors. JNK binding activity of the compounds correlated with their ability to inhibit lipopolysaccharide (LPS)-induced nuclear factor-κB/activating protein 1 (NF-κB/AP-1) activation in human monocytic THP-1Blue cells and interleukin-6 (IL-6) production by human MonoMac-6 cells. Thus, oximes with indenoquinoxaline and tryptanthrin nuclei can serve as specific small-molecule modulators for mechanistic studies of JNK, as well as potential leads for the development of anti-inflammatory drugs., (Copyright © 2018 Elsevier Masson SAS. All rights reserved.)

Formyl peptide receptors (FPRs) are expressed on a variety of leukocytes and play important roles in inflammation. Thus, FPR antagonists may represent novel therapeutics for modulating innate immunity and treating inflammatory diseases. Previously, 1H-pyrrol-2(5H)-ones were reported to be potent and competitive FPR1 antagonists. In the present studies, 42 additional 1H-pyrrol-2(5H)-one analogs were evaluated for FPR1 antagonist activity. We identified a number of novel competitive FPR1 antagonists that inhibited N-formylmethionyl-leucyl-phenylalanine (fMLF)-induced intracellular Ca 2+ mobilization in FPR1-transfected HL60 cells and effectively competed with WKYMVm-FITC for binding to FPR1 in FPR1-transfected RBL cells. The most active pyrroles inhibited human neutrophil Ca 2+ flux, chemotaxis, and adhesion to human epithelial cells, with the most potent being compounds 14 (4-benzoyl-1-hexyl-3-hydroxy-5-(4-hydroxy-3-methoxyphenyl)-2,5-dihydro-1H-pyrrol-2-one) and 17 (4-benzoyl-5-(2,5-dimethoxyphenyl)-3-hydroxy-1-(2-methoxyethyl)-2,5-dihydro-1H-pyrrol-2-one). In addition, these FPR1 antagonists inhibited fMLF-induced phosphorylation of extracellular signal-regulated kinases (ERK1/2) in FPR1-RBL cells, differentiated HL-60 cells, and human neutrophils. Most of the antagonists were specific for FPR1 and did not inhibit WKYMVM/WKYMVm-induced intracellular Ca 2+ mobilization in FPR2-HL60 cells, FPR3-HL60 cells, or interleukin 8-induced Ca 2+ flux in human neutrophils. Moreover, molecular modeling showed that the active pyrroles had a significantly higher degree of similarity with the FPR1 antagonist pharmacophore template as compared to inactive analogs. Thus, the 4-aroyl-3-hydroxy-5-phenyl-1H-pyrrol-2(5H)-one scaffold represents an important backbone for the development of novel FPR1 antagonists and could provide important clues for understanding the molecular structural requirements of FPR1 antagonists., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Essential oil extracts from Ferula iliensis have been used traditionally in Kazakhstan for treatment of inflammation and other illnesses. Because little is known about the biologic activity of these essential oils that contributes to their therapeutic properties, we analyzed their chemical composition and evaluated their phagocyte immunomodulatory activity. The main components of the extracted essential oils were ( E )-propenyl sec -butyl disulfide (15.7-39.4%) and ( Z )-propenyl sec -butyl disulfide (23.4-45.0%). Ferula essential oils stimulated [Ca 2+ ] i mobilization in human neutrophils and activated ROS production in human neutrophils and murine bone marrow phagocytes. Activation of human neutrophil [Ca 2+ ] i flux by Ferula essential oils was dose-dependently inhibited by capsazepine, a TRPV1 channel antagonist, indicating that TRPV1 channels mediate this response. Furthermore, Ferula essential oils stimulated Ca 2+ influx in TRPV1 channel-transfected HEK293 cells and desensitized the capsaicin-induced response in these cells. Additional molecular modeling with known TRPV1 channel agonists suggested that the active component is likely to be ( Z )-propenyl sec -butyl disulfide. Our results provide a cellular and molecular basis to explain at least part of the beneficial therapeutic properties of FEOs., (© Society for Leukocyte Biology.)

Preclinical Research Formyl peptide receptors (FPRs) are G-protein-coupled receptors that play an important role in the regulation of inflammatory process and cellular dysfunction. In humans, three different isoforms are expressed (FPR1, FPR2, and FPR3). FPR2 appears to be directly involved in the resolution of inflammation, an active process carried out by specific pro-resolving mediators that modulate specific receptors. Previously, we identified 2-arylacetamido pyridazin-3(2H)-ones as FPR1- or FPR2-selective agonists, as well as a large number of mixed-agonists for the three isoforms. Here, we report a new series of 2-arylacetamido pyridazinones substituted at position 5 and their development as FPR agonists. We also synthesized a new series of 2-oxothiazolones bearing a 4-bromophenylacetamido fragment, which was fundamental for activity in the pyridazinone series. The compounds of most interest were 4a, a potent, mixed FPR agonist recognized by all three isotypes (FPR1 EC 50  = 19 nM, FPR2 EC 50  = 43 nM, FPR3 EC 50  = 40 nM), and 4b, which had potent activity and a preference for FPR2 (EC 50  = 13 nM). These novel compounds may represent valuable tools for studying FPR activation and signaling. Drug Dev Res 78 : 49-62, 2017. © 2016 Wiley Periodicals, Inc., (© 2016 Wiley Periodicals, Inc.)

N-Formyl peptide receptors (FPRs: FPR1, FPR2, and FPR3) are G protein-coupled receptors that play key roles in modulating immune cells. FPRs represent potentially important therapeutic targets for the development of drugs that could enhance endogenous anti-inflammation systems associated with various pathologies, thereby reducing the progression of inflammatory conditions. Previously, we identified 2-arylacetamide pyridazin-3(2H)-ones as FPR1- or FPR2-selective agonists, as well as a large number of FPR1/FPR2-dual agonists and several mixed-agonists for the three FPR isoforms. Here, we report a new series of 2-arylacetamido-4-aniline pyridazin-3(2H)-ones substituted in position 5 as a further development of these FPR agonists. Chemical manipulation presented in this work resulted in mixed FPR agonists 8a, 13a and 27b, which had EC 50 values in nanomolar range. In particular, compound 8a showed a preference for FPR1 (EC 50 =45nM), while 13a and 27b showed a moderate preference for FPR2 (EC 50 =35 and 61nM, respectively). Thus, these compounds may represent valuable tools for studying FPR activation and signaling., (Copyright © 2016. Published by Elsevier Ltd.)

N-Formyl peptide receptors (FPRs) are G protein-coupled receptors (GPCRs) that play critical roles in inflammatory reactions, and FPR-specific interactions can possibly be used to facilitate the resolution of pathological inflammatory reactions. We here report the synthesis and biological evaluation of six pairs of chiral ureidopropanamido derivatives as potent and selective formyl peptide receptor-2 (FPR2) agonists that were designed starting from our lead agonist (S)-3-(1H-indol-3-yl)-2-[3-(4-methoxyphenyl)ureido]-N-[[1-(5-methoxy-2-pyridinyl)cyclohexyl]methyl]propanamide ((S)-9a). The new compounds were obtained in overall yields considerably higher than (S)-9a. Several of the new compounds showed agonist properties comparable to that of (S)-9a along with higher selectivity over FPR1. Molecular modeling was used to define chiral recognition by FPR2. In vitro metabolic stability of selected compounds was also assessed to obtain preliminary insight on drug-like properties of this class of compounds., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

c-Jun N-terminal kinases (JNKs) participate in many physiologic and pathologic processes, including inflammatory diseases. We recently synthesized the sodium salt of IQ-1S (11H-indeno[1,2-b]quinoxalin-11-one oxime) and demonstrated that it is a high-affinity JNK inhibitor and inhibits murine delayed-type hypersensitivity. Here we show that IQ-1S is highly specific for JNK and that its neutral form is the most abundant species at physiologic pH. Molecular docking of the IQ-1S syn isomer into the JNK1 binding site gave the best pose, which corresponded to the position of cocrystallized JNK inhibitor SP600125 (1,9-pyrazoloanthrone). Evaluation of the therapeutic potential of IQ-1S showed that it inhibited matrix metalloproteinase 1 and 3 gene expression induced by interleukin-1β in human fibroblast-like synoviocytes and significantly attenuated development of murine collagen-induced arthritis (CIA). Treatment with IQ-1S either before or after induction of CIA resulted in decreased clinical scores, and joint sections from IQ-1S-treated CIA mice exhibited only mild signs of inflammation and minimal cartilage loss compared with those from control mice. Collagen II-specific antibody responses were also reduced by IQ-1S treatment. By contrast, the inactive ketone derivative 11H-indeno[1,2-b]quinoxalin-11-one had no effect on CIA clinical scores or collagen II-specific antibody titers. IQ-1S treatment also suppressed proinflammatory cytokine and chemokine levels in joints and lymph node cells. Finally, treatment with IQ-1S increased the number of Foxp3(+)CD4(+)CD25(+) regulatory T cells in lymph nodes. Thus, IQ-1S can reduce inflammation and cartilage loss associated with CIA and can serve as a small-molecule modulator for mechanistic studies of JNK function in rheumatoid arthritis., (Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.)

Several plant extracts, including certain polyphenols, prime innate lymphocytes and enhance responses to secondary stimuli. Oenothein B, a polyphenol isolated from Epilobium angustifolium and other plant sources, enhances IFNγ production by both bovine and human NK cells and T cells, alone and in response to secondary stimulation by cytokines or tumor cells. Innate immune cell responsiveness is known to be affected by aging, but whether polyphenol responses by these cells are also impacted by aging is not known. Therefore, we examined oenothein B responsiveness in T cells from cord blood, young, and adult donors. We found that oenothein B stimulates bovine and human T cells from individuals over a broad range of ages, as measured by increased IL-2Rα and CD69 expression. However, clear differences in induction of cytokine production by T cells were seen. In T cells from human cord blood and bovine calves, oenothein B was unable to induce IFNγ production. However, oenothein B induced IFNγ production by T cells from adult humans and cattle. In addition, oenothein B induced GM-CSF production by human adult T cells, but not cord blood T cells. Within the responsive T cell population, we found that CD45RO+ memory T cells expressed more cytokines in response to oenothein B than CD45RO- T cells. In summary, our data suggest that the immunostimulation of T cells by oenothein B is influenced by age, particularly with respect to immune cytokine production., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Formyl peptide receptors (FPRs) are G protein-coupled receptors (GPCRs) expressed on a variety of cell types. Because FPRs play an important role in the regulation of inflammatory reactions implicated in disease pathogenesis, FPR antagonists may represent novel therapeutics for modulating innate immunity. Previously, 4H-chromones were reported to be potent and competitive FPR1 antagonists. In the present studies, 96 additional chromone analogs, including related synthetic and natural isoflavones were evaluated for FPR1 antagonist activity. We identified a number of novel competitive FPR1 antagonists that inhibited fMLF-induced intracellular Ca2+ mobilization in FPR1-HL60 cells and effectively competed with WKYMVm-FITC for binding to FPR1 in FPR1-HL60 and FPR1-RBL cells. Compound 10 (6-hexyl-2-methyl-3-(1-methyl-1H-benzimidazol-2-yl)-4-oxo-4H-chromen-7-yl acetate) was found to be the most potent FPR1-specific antagonist, with binding affinity Ki∼100 nM. These chromones inhibited Ca2+ flux and chemotaxis in human neutrophils with nanomolar-micromolar IC50 values. In addition, the most potent novel FPR1 antagonists inhibited fMLF-induced phosphorylation of extracellular signal-regulated kinases (ERK1/2) in FPR1-RBL cells. These antagonists were specific for FPR1 and did not inhibit WKYMVM/WKYMVm-induced intracellular Ca2+ mobilization in FPR2-HL60 cells, FPR3-HL60 cells, RBL cells transfected with murine Fpr1, or interleukin 8-induced Ca2+ flux in human neutrophils and RBL cells transfected with CXC chemokine receptor 1 (CXCR1). Moreover, pharmacophore modeling showed that the active chromones had a significantly higher degree of similarity with the pharmacophore template as compared to inactive analogs. Thus, the chromone/isoflavone scaffold represents a relevant backbone for development of novel FPR1 antagonists., (Copyright © 2014 Elsevier Inc. All rights reserved.)

The development of new advances in the understanding of neutrophil biochemistry requires effective procedures for isolating purified neutrophil populations. Although methods for human neutrophil isolation are now standard, similar procedures for isolating neutrophils from many of the nonhuman species used to model human diseases are not as well developed. Since neutrophils are reactive cells, the method of isolation is extremely important to avoid isolation technique-induced alterations in cell function. We present methods here for reproducibly isolating highly purified neutrophils from large animals (bovine, equine, ovine), small animals (murine and rabbit), and nonhuman primates (cynomolgus macaques), and describe optimized details for obtaining the highest cell purity, yield, and viability. We also describe methods to verify phagocytic capacity in the purified cell populations using a flow cytometry-based phagocytosis assay.

Formyl peptide receptors (FPRs) play an essential role in the regulation of endogenous inflammation and immunity. In the present studies, a large series of pyridazin-3(2H)-one derivatives bearing an arylacetamide chain at position 2 was synthesized and tested for FPR agonist activity. The pyridazin-3(2H)-one ring was confirmed to be an appropriate scaffold to support FPR agonist activity, and its modification at the 4 and 6 positions led to the identification of additional active agonists, which induced intracellular Ca(2+) flux in HL-60 cells transfected with either FPR1, FPR2, or FPR3. Seven formyl peptide receptor 1 (FPR1)-specific and several mixed FPR1/FPR2 dual agonists were identified with low micromolar EC50 values. Furthermore, these agonists also activated human neutrophils, inducing intracellular Ca(2+) flux and chemotaxis. Finally, molecular docking studies indicated that the most potent pyridazin-3(2H)-ones overlapped in their best docking poses with fMLF and WKYMVM peptides in the FPR1 and FPR2 ligand binding sites, respectively. Thus, pyridazinone-based compounds represent potential lead compounds for further development of selective and/or potent FPR agonists., (Copyright © 2013 Elsevier Masson SAS. All rights reserved.)

Extracts of leaves of different species of the genus Combretum have been used historically to treat a variety of medicinal problems. However, little is known about the active components conferring therapeutic properties to these extracts. In the present studies, we evaluated biochemical properties and immunomodulatory activity of polysaccharides isolated from the leaves of Combretum racemosum. Water-soluble polysaccharides from leaves of C. racemosum were extracted and fractionated by DEAE-cellulose and Diaion HP-20 to obtain a Diaion-bound fraction, designated Combretum polysaccharide-acidic bound or CP-AB, which was eluted with methanol, and an unbound fraction, designated as CP-AU. Molecular weight determination, sugar analysis, and other physical and chemical characterization of the fractions were performed. Fraction CP-AU (mol. weight 5.0 kDa) contained type II arabinogalactan and had potent immunomodulatory activity, inducing the production of interleukin (IL)-1β, -6, -10, and tumor necrosis factor-α (TNF-α) by human peripheral blood mononuclear cells (PBMC) and MonoMac-6 monocytic cells. Likewise, intraperitoneal administration of CP-AU increased in vivo serum levels of IL-6 and monocyte chemoattractant protein-1 (MCP-1) in mice. CP-AU-induced secretion of TNF-α in PBMC was prevented by Toll-like receptor 4 (TLR4) antagonist LPS-RS. Treatment with CP-AU induced phosphorylation of Akt2, Akt3, GSK-3β, HSP27, mTOR, and all p38 MAPK isoforms (α, β, δ, and γ), as well as stimulation of AP-1/NF-κB transcriptional activity. In addition, CP-AU effectively agglutinated erythrocytes from several species, including human, mouse, and rabbit. In contrast, fraction CP-AB was inactive in all biological tests, including cytokine production and hemagglutination. These data suggest that at least part of the beneficial therapeutic effects reported for the water extracts of leaves from C. racemosum are due to modulation of leukocyte functions., (Copyright © 2013 Elsevier B.V. All rights reserved.)

N-formyl peptide receptors (FPRs) are G protein-coupled receptors (GPCRs) that play critical roles in inflammatory reactions, and FPR-specific interactions can possibly be used to facilitate the resolution of pathological inflammatory reactions. Recent studies indicated that FPRs have stereo-selective preference for chiral ligands. Here, we investigated the structure-activity relationship of 24 chiral ureidopropanamides, including previously reported compounds PD168368/PD176252 and their close analogs, and used molecular modeling to define chiral recognition by FPR2. Unlike previously reported 6-methyl-2,4-disubstituted pyridazin-3(2H)-ones, whose R-forms preferentially activated FPR1/FPR2, we found that four S-enantiomers in the seven ureidopropanamide pairs tested preferentially activated intracellular Ca(2+) flux in FPR2-transfected cells, while the R-counterpart was more active in two enantiomer pairs. Thus, active enantiomers of FPR2 agonists can be in either R- or S-configurations, depending on the molecular scaffold and specific substituents at the chiral center. Using molecular modeling approaches, including field point methodology, homology modeling, and docking studies, we propose a model that can explain stereoselective activity of chiral FPR2 agonists. Importantly, our docking studies of FPR2 chiral agonists correlated well with the FPR2 pharmacophore model derived previously. We conclude that the ability of FPR2 to discriminate between the enantiomers is the consequence of the arrangement of the three asymmetric hydrophobic subpockets at the main orthosteric FPR2 binding site with specific orientation of charged regions in the subpockets., (Copyright © 2012 Elsevier Inc. All rights reserved.)

A series of chiral pyridazin-3(2H)-ones was synthesized, separated as pure enantiomers, and evaluated for N-formyl peptide receptor (FPR) agonist activity. Characterization of the purified enantiomers using combined chiral HPLC and chiroptical studies (circular dichroism, allowed unambiguous assignment of the absolute configuration for each pair of enantiomers). Evaluation of the ability of racemic mixtures and purified enantiomers to stimulate intracellular Ca(2+) flux in FPR-transfected HL-60 cells and human neutrophils and to induce β-arrestin recruitment in FPR-transfected CHO-K1 cells showed that many enantiomers were potent agonists, inducing responses in the sub-micromolar to nanomolar range. Furthermore, FPRs exhibited enantiomer selectivity, generally preferring the R-(-)-forms over the S-(+)-enantiomers. Finally, we found that elongation of the carbon chain in the chiral center of the active compounds generally increased biological activity. Thus, these studies provide important new information regarding molecular features involved in FPR ligand preference and report the identification of a novel series of FPR agonists., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Human N-formyl peptide receptor 1 (FPR1) is a G protein-coupled receptor (GPCR) involved in host defense and sensing cellular damage. Since structure-based ligand design for many GPCRs, including FPR1, is restricted by the lack of experimental three dimensional structures, homology modeling has been widely used to study GPCR-ligand binding. Indeed, receptor-ligand binding mode predictions can be derived from homology modeling with supporting ligand information. In the present work, we report comparative docking studies of 2-(benzimidazol-2-ylthio)-N-phenylacetamide derived FPR1 agonists, identified here and previously, with several known FPR1 peptide agonists in a FPR1 homology model that is based on the crystal structure of bovine rhodopsin. We found that the binding pocket of the most active molecules shares some common features with high affinity FPR1 peptide agonists, suggesting that they may bind to similar binding sites. Classification tree analysis led to the derivation of a good recognition model based on four amino acid descriptors for distinguishing FPR1 ligands from inactive analogs. Hence, the corresponding residues (Thr199, Arg201, Gly202, and Ala261) can be considered as markers of important areas in the ligand binding site. Concurrently, we identified several unique binding features of benzimidazole derivatives and showed that alkoxy-substituents of the benzimidazole ring are located within a FPR1 hole bounded by Thr199, Thr265, Ile268, and Leu271 or in a groove in the vicinity of Leu198, Arg201, Gly202, and Arg205. The understanding of these molecular features will likely prove beneficial in future design of novel FPR1 agonists based on the benzimidazole scaffold.

Human neutrophil elastase (HNE) plays an important role in tumour invasion and inflammation. A series of N-benzoylindazoles was synthesized and evaluated for their ability to inhibit HNE. We found that this scaffold is appropriate for HNE inhibitors and that the benzoyl fragment at position 1 is essential for activity. The most active compounds inhibited HNE activity with IC₅₀ values in the submicromolar range. Furthermore, docking studies indicated that the geometry of an inhibitor within the binding site and energetics of Michaelis complex formation were key factors influencing the inhibitor's biological activity. Thus, N-benzoylindazole derivatives and their analogs represent novel structural templates that can be utilized for further development of efficacious HNE inhibitors., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

N-formyl peptide receptors (FPRs) are important in host defense. Because of the potential for FPRs as therapeutic targets, recent efforts have focused on identification of non-peptide agonists for two FPR subtypes, FPR1 and FPR2. Given that a number of specific small-molecule agonists have recently been identified, we hypothesized that computational structure-activity relationship (SAR) analysis of these molecules could provide new information regarding molecular features required for activity. We used a training set of 71 compounds, including 10 FPR1-specific agonists, 36 FPR2-specific agonists, and 25 non-active analogs. A sequence of (1) one-way analysis of variance selection, (2) cluster analysis, (3) linear discriminant analysis, and (4) classification tree analysis led to the derivation of SAR rules with high (95.8%) accuracy for correct classification of compounds. These SAR rules revealed key features distinguishing FPR1 versus FPR2 agonists. To verify predictive ability, we evaluated a test set of 17 additional FPR agonists, and found that the majority of these agonists (>94%) were classified correctly as agonists. This study represents the first successful application of classification tree methodology based on atom pairs to SAR analysis of FPR agonists. Importantly, these SAR rules represent a relatively simple classification approach for virtual screening of FPR1/FPR2 agonists., (Copyright © 2010 Elsevier Masson SAS. All rights reserved.)

Shilajit has been used traditionally in folk medicine for the treatment of a variety of disorders, including syndromes involving excessive complement activation. Extracts of Shilajit contain significant amounts of fulvic acid (FA), and it has been suggested that FA is responsible for many therapeutic properties of Shilajit. However, little is known regarding the physical and chemical properties of Shilajit extracts, and nothing is known about their effects on the complement system. To address this issue, extracts of commercial Shilajit were fractionated using anion exchange and size-exclusion chromatography. One neutral (S-I) and two acidic (S-II and S-III) fractions were isolated, characterized and compared with standardized FA samples. The most abundant fraction (S-II) was further fractionated into three sub-fractions (S-II-1 to S-II-3). The van Krevelen diagram showed that the Shilajit fractions are the products of polysaccharide degradation, and all fractions, except S-II-3, contained type II arabinogalactan. All Shilajit fractions exhibited dose-dependent complement-fixing activity in vitro with high potency. Furthermore, a strong correlation was found between the complement-fixing activity and carboxylic group content in the Shilajit fractions and other FA sources. These data provide a molecular basis to explain at least part of the beneficial therapeutic properties of Shilajit and other humic extracts., ((c) 2008 John Wiley & Sons, Ltd.)

Previously, we screened a series of arylcarboxylic acid hydrazide derivatives for their ability to induce macrophage tumor necrosis factor alpha (TNF-alpha) production and identified 16 such compounds. In the present study, we evaluated 23 additional arylcarboxylic acid hydrazides and found that seven of these compounds also induced macrophage TNF-alpha production, representing novel compounds with this activity. The total set of active compounds was then used for computational structure-activity relationship (SAR) analysis to further optimize lead molecules. A sequence of (1) linear discriminant analysis, (2) classification tree analysis with linear combination, and (3) univariate splits based on atom pair descriptors led to the derivation of SAR rule-based algorithms with fitting accuracy of 96.5%, 91.9%, and 84.9%, respectively. The SAR rules obtained from classification tree analysis with univariate splits, which was based on three atom pair descriptors only, revealed that the main factors influencing agonist activity of arylcarboxylic acid hydrazide derivatives were the presence of a methyl or trifluoromethyl group in the benzene ring attached to the furan moiety, an alkoxy group in the aromatic ring near the methylenehydrazide linker, and two or more halogen atoms (chlorine or bromine) on one side of the dumbbell-shaped hydrazide molecule opposed by an aromatic moiety on the opposite side of the molecule. Thus, these rules represent a relatively simple classification approach for de novo design of small-molecule inducers of macrophage TNF-alpha production.

Development of immunomodulatory agents that enhance innate immune responses represents a promising strategy for combating infectious diseases. In the present studies, we screened a series of 71 arylcarboxylic acid hydrazide derivatives for their ability to induce macrophage tumor necrosis factor alpha (TNF-alpha) production and identified six such compounds, including one compound previously shown to be a formyl peptide receptor (FPR/FPRL1) agonist. The two most potent compounds [compound 1, nicotinic acid [5-(3-bromophenyl)-2-furyl]methylene-hydrazide; compound 2, 4-fluoro-benzoic acid [5-(3-trifluoromethyl-phenyl)-2-furyl]-methylene-hydrazide] were selected for further analysis. These compounds induced de novo production of TNF-alpha in a dose- and time-dependent manner in human and murine monocyte/macrophage cell lines and in primary macrophages. These compounds also induced mobilization of intracellular Ca(2+), production of reactive oxygen species, and chemotaxis in human and murine phagocytes. Induction of macrophage TNF-alpha production was pertussis toxin-sensitive, and analysis of the cellular target of these compounds showed that they were FPRL1-specific agonists and that this response was blocked by FPR/FPRL1 and FPRL1-specific antagonists. In addition, pharmacophore modeling showed a high degree of similarity for low-energy conformations of these two compounds to the current pharmacophore model for FPR ligands ( Mol Pharmacol 68: 1301-1310, 2005 ). Overall, these compounds represent novel FPRL1 agonists that induce TNF-alpha, a response distinct from those induced by other known FPR and FPRL1 agonists.

The leaves of Artemisia species have been traditionally used for prevention and treatment of a number of diseases. In this study, five polysaccharide fractions (designated A-I-A-V) were isolated from the leaves of Artemisia tripartita Rydb. by the sequential use of hot-water extraction, ethanol precipitation, ultra-filtration, and chromatography. The homogeneity and average molecular weight of each fraction were determined by high performance size-exclusion chromatography. Sugar composition analysis revealed that Artemisia polysaccharides consisted primarily of xylose, glucose, arabinose, galactose, and galactosamine. Moreover, all fractions contained at least 3.4% sulfate, and fractions A-II-A-V contained an arabinogalactan type II structure. All fractions exhibited macrophage-activating activity, enhancing production of intracellular reactive oxygen species and release of nitric oxide, interleukin 6, interleukin 10, tumor necrosis factor alpha, and monocyte chemotactic protein 1. In addition, all fractions exhibited scavenging activity for reactive oxygen species generated enzymatically or produced extracellularly by human neutrophils. Finally, fractions A-I and A-V exhibited complement-fixing activity. Taken together, our results provide a molecular basis to explain at least part of the beneficial therapeutic effects of Artemisia extracts, and suggest the possibility of using Artemisia polysaccharides as an immunotherapeutic adjuvant.

Quantitative structure-activity relationship (QSAR) models are useful in understanding how chemical structure relates to the biological activity of natural and synthetic chemicals and for design of newer and better therapeutics. In the present study, 46 flavonoids and related polyphenols were evaluated for direct/indirect antioxidant activity in three different assay systems of increasing complexity (chemical, enzymatic, and intact phagocytes). Based on these data, two different QSAR models were developed using (i) physicochemical and structural (PC&S) descriptors to generate multiparameter partial least squares (PLS) regression equations derived from optimized molecular structures of the tested compounds and (ii) a partial 3D comparison of the 46 compounds with local fingerprints obtained from fragments of the molecules by the frontal polygon (FP) method. We obtained much higher QSAR correlation coefficients (r) for flavonoid end-point antioxidant activity in all three assay systems using the FP method (0.966, 0.948, and 0.965 for datasets evaluated in the biochemical, enzymatic, and whole cell assay systems, respectively). Furthermore, high leave-one-out cross-validation coefficients (q2) of 0.907, 0.821, and 0.897 for these datasets, respectively, indicated enhanced predictive ability and robustness of the model. Using the FP method, structural fragments (submolecules) responsible for the end-point antioxidant activity in the three assay systems were also identified. To our knowledge, this is the first QSAR model derived for description of flavonoid direct/indirect antioxidant effects in a cellular system, and this model could form the basis for further drug development of flavonoid-like antioxidant compounds with therapeutic potential.

The chemokine receptor, CXCR2, plays an important role in recruiting granulocytes to sites of inflammation and has been proposed as an important therapeutic target. A number of CXCR2 antagonists have been synthesized and evaluated; however, quantitative structure-activity relationship (QSAR) models have not been developed for these molecules. Most CXCR2 antagonists can be grouped into four related categories: N,N'-diphenylureas, nicotinamide N-oxides, quinoxalines, and triazolethiols. Based on these categories, we developed a QSAR model for 59 nonpeptide antagonists of CXCR2 using a partial 3D comparison of the antagonists with local fingerprints obtained from rigid and flexible fragments of the molecules. Each compound was represented by calculated structural descriptors that encoded atomic charge, molar refraction, hydrophobicity, and geometric features. We obtained good conventional R(2) coefficients, high leave-one-out cross-validated values for the whole dataset (R(cv)(2)=0.785), as well as for the dataset divided into subsets of triazolethiol derivatives (R(cv)(2)=0.821) and joint subset of N'-diphenylureas, nicotinamide N-oxides, N,N'-diphenylureas, and quinoxaline derivatives and quinoxalines derivatives (R(cv)(2)=0.766), indicating a good predictive ability and robustness of the model. Additionally, charge distribution was found to be a significant contributor in modeling whole dataset. Using our model, structural fragments (submolecules) responsible for the antagonist activity were also identified. These data suggest the QSAR models developed here may be useful in guiding the design of CXCR2 antagonists from molecular fragments.