Time-resolved in situ assembly of the leukotriene-synthetic 5-lipoxygenase/5-lipoxygenase-activating protein complex in blood leukocytes.

5-Lipoxygenase (5-LO) catalyzes the initial steps in the biosynthesis of proinflammatory leukotrienes. Upon cell activation, 5-LO translocates to the nuclear membrane where arachidonic acid is transferred by 5-LO-activating protein (FLAP) to 5-LO for metabolism. Although previous data indicate association of 5-LO with FLAP, the in situ assembly of native 5-LO/FLAP complexes remains elusive.

The acylphloroglucinols hyperforin and myrtucommulone A cause mitochondrial dysfunctions in leukemic cells by direct interference with mitochondria.

The acylphloroglucinols hyperforin (Hypf) and myrtucommulone A (MC A) induce death of cancer cells by triggering the intrinsic/mitochondrial pathway of apoptosis, accompanied by a loss of the mitochondrial membrane potential and release of cytochrome c. However, the upstream targets and mechanisms leading to these mitochondrial events in cancer cells remain elusive. Here we show that Hypf and MC A directly act on mitochondria derived from human leukemic HL-60 cells and thus, disrupt mitochondrial functions.

Characterization of the interaction of human 5-lipoxygenase with its activating protein FLAP.

Human 5-lipoxygenase (5-LO) is the key enzyme in the formation of leukotrienes (LTs), important mediators of inflammation. Cellular 5-LO activity is regulated in a complex manner, e.g.

Pirinixic acids: flexible fatty acid mimetics with various biological activities.

Pirinixic acid is a typical fatty acid mimetic and was developed as synthetic antihyperlipidemic agent. While its target remained unknown in the early development, it has later been characterized as dual PPARα/γ agonist. Based on this activity, pirinixic acid has served as a lead compound for several structure-activity relationship (SAR) studies addressing diverse targets for lipid mimetics.

Design, synthesis and evaluation of semi-synthetic triazole-containing caffeic acid analogues as 5-lipoxygenase inhibitors.

In this work the synthesis, structure-activity relationship (SAR) and biological evaluation of a novel series of triazole-containing 5-lipoxygenase (5-LO) inhibitors are described. The use of structure-guided drug design techniques provided compounds that demonstrated excellent 5-LO inhibition with IC50 of 0.2 and 3.

Synthesis and biological evaluation of novel myrtucommulones and structural analogues that target mPGES-1 and 5-lipoxygenase.

The natural acylphloroglucinol myrtucommulone A (1) inhibits microsomal prostaglandin E2 synthase (mPGES)-1 and 5-lipoxygenase (5-LO), and induces apoptosis of cancer cells. Starting from 1 as lead, 28 analogues were synthesized following a straightforward modular strategy with high yielding convergent steps. Major structural variations concerned (I) replacement of the syncarpic acid moieties by dimedone or indandione, (II) cyclization of the syncarpic acid with the acylphloroglucinol core, and (III) substitution of the methine bridges and the acyl residue with isopropyl, isobutyl, n-pentyl or phenyl groups, each.

Perspective of microsomal prostaglandin E2 synthase-1 as drug target in inflammation-related disorders.

Prostaglandin (PG)E2 encompasses crucial roles in pain, fever, inflammation and diseases with inflammatory component, such as cancer, but is also essential for gastric, renal, cardiovascular and immune homeostasis. Cyclooxygenases (COX) convert arachidonic acid to the intermediate PGH2 which is isomerized to PGE2 by at least three different PGE2 synthases. Inhibitors of COX - non-steroidal anti-inflammatory drugs (NSAIDs) - are currently the only available therapeutics that target PGE2 biosynthesis.

Discovery of novel, non-acidic mPGES-1 inhibitors by virtual screening with a multistep protocol.

Microsomal prostaglandin E2 synthase-1 (mPGES-1) inhibitors are considered as potential therapeutic agents for the treatment of inflammatory pain and certain types of cancer. So far, several series of acidic as well as non-acidic inhibitors of mPGES-1 have been discovered. Acidic inhibitors, however, may have issues, such as loss of potency in human whole blood and in vivo, stressing the importance of the design and identification of novel, non-acidic chemical scaffolds of mPGES-1 inhibitors.

α-Tocopherol long-chain metabolite α-13'-COOH affects the inflammatory response of lipopolysaccharide-activated murine RAW264.7 macrophages.

Scope: Inflammatory response of macrophages is regulated by vitamin E forms. The long-chain metabolite α-13'-carboxychromanol (α-13'-COOH) is formed by hepatic α-tocopherol (α-TOH) catabolism and acts as a regulatory metabolite via pathways that are different from its metabolic precursor.

Methods And Results: Using semisynthetically-derived α-13'-COOH we profiled its action on LPS-induced expression of pro- and anti-inflammatory genes using RT-qPCR and of key proteins by Western blotting.

A procedure for efficient non-viral siRNA transfection of primary human monocytes using nucleofection.

Monocytes are an important constituent of the innate immune system. Therefore, manipulating gene expression of primary human monocytes is a crucial mean to study and characterize the functions of targeted proteins in monocytes. Gene silencing by transfection of cells with small interfering RNA (siRNA) leading to the degradation of the corresponding mRNA and thus to reduced target protein levels is an important tool to investigate gene and protein function of interest.

Novel series of benzoquinones with high potency against 5-lipoxygenase in human polymorphonuclear leukocytes.

5-Lipoxygenase (5-LO) is a potential target for pharmacological intervention with various inflammatory and allergic diseases. Starting from the natural dual 5-LO/microsomal prostaglandin E2 synthase (mPGES)-1 inhibitor embelin (2,5-dihydroxy-3-undecyl-1,4-benzoquinone, 2) that suppresses 5-LO activity in human primary leukocytes with IC50 = 0.8-2 μM, we synthesized 48 systematically modified derivatives of 2.

Structural Insights for the Optimization of Dihydropyrimidin-2(1H)-one Based mPGES-1 Inhibitors.

The recently crystallized structure of microsomal prostaglandin E2 synthase 1 (mPGES-1) in complex with the inhibitor LVJ (PDB code: 4BPM) offered new structural information for the optimization of the previously identified lead compound 1 (IC50 = 4.16 ± 0.47 μM), which contains the privileged dihydropyrimidin-2-one chemical core.

Myxochelins target human 5-lipoxygenase.

Extracts of the predatory myxobacterium Pyxidicoccus fallax HKI 727 showed antiproliferative effects on leukemic K-562 cells. Bioactivity-guided fractionation led to the isolation of the bis-catechol myxochelin A and two new congeners. The biosynthetic origin of myxochelins C and D was confirmed by feeding studies with isotopically labeled precursors.

Progesterone rapidly down-regulates the biosynthesis of 5-lipoxygenase products in human primary monocytes.

5-Lipoxygenase (5-LO), the key enzyme in the biosynthesis of pro-inflammatory leukotrienes (LTs) from arachidonic acid, is regulated by androgens in human neutrophils and monocytes accounting for sex differences in LT formation. Here we show that progesterone suppresses the synthesis of 5-LO metabolites in human primary monocytes. 5-LO product formation in monocytes stimulated with Ca(2+)-ionophore A23187 or with lipopolysaccharide/formyl peptide was suppressed by progesterone at concentrations of 10-100 nM in cells from females and at 1 μM in cells from males.

Role of p38 mitogen-activated protein kinase in linking stearoyl-CoA desaturase-1 activity with endoplasmic reticulum homeostasis.

Endoplasmic reticulum (ER) homeostasis is regulated by a network of signaling pathways to which stearoyl-CoA desaturase (SCD)-1, p38 mitogen-activated protein kinase (MAPK) and the unfolded protein response (UPR) belong. Because all these pathways are located at the interface of cell cycle control and cell stress, we hypothesized a cross-regulation. Interference with SCD-1, either by small interfering (si)RNA or the specific SCD-1 inhibitor CAY10566 (EC₅₀ 1 µM; ≥ 24 h), specifically induced phosphorylation and thus activation of p38 MAPK in NIH-3T3 mouse fibroblasts (1.

SAR-studies of γ-secretase modulators with PPARγ-agonistic and 5-lipoxygenase-inhibitory activity for Alzheimer's disease.

We present the design, synthesis and biological evaluation of compounds containing a 2-(benzylidene)hexanoic acid scaffold as multi-target directed γ-secretase-modulators. Broad structural variations were undertaken to elucidate the structure-activity-relationships at the 5-position of the aromatic core. Compound 13 showed the most potent activity profile with IC50 values of 0.

Dual induction of mitochondrial apoptosis and senescence in chronic myelogenous leukemia by myrtucommulone A.

Despite recent advances in the treatment of chronic myelogenous leukemia (CML), the development of drug resistance and minimal residual disease remain major challenges for the treatment of CML patients, thus highlighting the need to develop innovative new approaches to improve therapeutic outcome. Myrtucommulone A (MCA) is a nonprenylated acylphloroglucinol isolated from the leaves of myrtle, a plant traditionally used in folk medicine. To date, studies addressing bioactivities of myrtle and its specific components are rare.

Revealing the macromolecular targets of complex natural products.

Natural products have long been a source of useful biological activity for the development of new drugs. Their macromolecular targets are, however, largely unknown, which hampers rational drug design and optimization. Here we present the development and experimental validation of a computational method for the discovery of such targets.

Resveratrol post-transcriptionally regulates pro-inflammatory gene expression via regulation of KSRP RNA binding activity.

Resveratrol shows beneficial effects in inflammation-based diseases like cancer, cardiovascular and chronic inflammatory diseases. Therefore, the molecular mechanisms of the anti-inflammatory resveratrol effects deserve more attention. In human epithelial DLD-1 and monocytic Mono Mac 6 cells resveratrol decreased the expression of iNOS, IL-8 and TNF-α by reducing mRNA stability without inhibition of the promoter activity.

Structure and biosynthetic assembly of gulmirecins, macrolide antibiotics from the predatory bacterium Pyxidicoccus fallax.

The gulmirecins constitute a new class of glycosylated macrolides that were isolated from the predatory bacterium Pyxidicoccus fallax HKI 727. Their structures were solved by a combination of NMR spectroscopic experiments and chemical derivatization. Analysis of the annotated gulmirecin gene cluster complemented the configurational assignment and provided insights into the stereochemical course of the biosynthetic assembly.

Multi-target approach for natural products in inflammation.

Although an increasing number of studies show the (pre)clinical efficiency and safety of multi-target natural products, they are still underrepresented as starting points for multi-target drug discovery. This article provides an overview about the multi-target drug concept and discusses strategies to use the enormous pharmacological knowledge of natural products with privileged structures (i.e.

5-Lipoxygenase, a key enzyme for leukotriene biosynthesis in health and disease.

5-Lipoxygenase (5-LOX) catalyzes two steps in the biosynthesis of leukotrienes (LTs), lipid mediators of inflammation derived from arachidonic acid. In this review we focus on 5-LOX biochemistry including 5-LOX interacting proteins and regulation of enzyme activity. LTs function in normal host defense, and have roles in many disease states where acute or chronic inflammation is part of the pathophysiology, as briefly summarized at the end of this chapter.

Targeting V-ATPase in primary human monocytes by archazolid potently represses the classical secretion of cytokines due to accumulation at the endoplasmic reticulum.

The macrolide archazolid inhibits vacuolar-type H(+)-ATPase (V-ATPase), a proton-translocating enzyme involved in protein transport and pH regulation of cell organelles, and potently suppresses cancer cell growth at low nanomolar concentrations. In view of the growing link between inflammation and cancer, we investigated whether inhibition of V-ATPase by archazolid may affect primary human monocytes that can promote cancer by sustaining inflammation through the release of tumor-promoting cytokines. Human primary monocytes express V-ATPase, and archazolid (10-100nM) increases the vesicular pH in these cells.