title: Potent inhibition of human 5-lipoxygenase and microsomal prostaglandin E₂ synthase-1 by the anti-carcinogenic and anti-inflammatory agent embelin.
abstract: Embelin (2,5-dihydroxy-3-undecyl-1,4-benzoquinone) possesses anti-inflammatory and anti-carcinogenic properties in vivo, and these features have been related to interference with multiple targets including XIAPs, NFκB, STAT-3, Akt and mTOR. However, interference with these proteins requires relatively high concentrations of embelin (IC₅₀>4 μM) and cannot fully explain its bioactivity observed in several functional studies. Here we reveal human 5-lipoxygenase (5-LO) and microsomal prostaglandin E₂ synthase (mPGES)-1 as direct molecular targets of embelin. Thus, embelin potently suppressed the biosynthesis of eicosanoids by selective inhibition of 5-LO and mPGES-1 with IC₅₀=0.06 and 0.2 μM, respectively. In intact human polymorphonuclear leukocytes and monocytes, embelin consistently blocked the biosynthesis of various 5-LO products regardless of the stimulus (fMLP or A23187) with IC₅₀=0.8-2 μM. Neither the related human 12- and 15-LO nor the cyclooxygenases-1 and -2 or cytosolic phospholipase A₂ were significantly affected by 10 μM embelin. Inhibition of 5-LO and mPGES-1 by embelin was (I) essentially reversible after wash-out, (II) not impaired at higher substrate concentrations, (III) unaffected by inclusion of Triton X-100, and (IV) did not correlate to its proposed antioxidant properties. Docking simulations suggest concrete binding poses in the active sites of both 5-LO and mPGES-1. Because 5-LO- and mPGES-1-derived eicosanoids play roles in inflammation and cancer, the interference of embelin with these enzymes may contribute to its biological effects and suggests embelin as novel chemotype for development of dual 5-LO/mPGES-1 inhibitors.
authors.affiliation: Chair of Pharmaceutical/Medicinal Chemistry, Institute of Pharmacy, Friedrich-Schiller-University Jena, Philosophenweg 14, D-07743 Jena, Germany.
authors.forename: Anja M
authors.initials: AM
authors.lastname: Schaible
authors.forename: Heidi
authors.initials: H
authors.lastname: Traber
authors.forename: Veronika
authors.initials: V
authors.lastname: Temml
authors.forename: Stefan M
authors.initials: SM
authors.lastname: Noha
authors.forename: Rosanna
authors.initials: R
authors.lastname: Filosa
authors.forename: Antonella
authors.initials: A
authors.lastname: Peduto
authors.forename: Christina
authors.initials: C
authors.lastname: Weinigel
authors.forename: Dagmar
authors.initials: D
authors.lastname: Barz
authors.forename: Daniela
authors.initials: D
authors.lastname: Schuster
authors.forename: Oliver
authors.initials: O
authors.lastname: Werz
mesh_terms: D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D000975:Antioxidants / Q000494:pharmacology; D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism*; D016227:Benzoquinones / Q000494:pharmacology*; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D015777:Eicosanoids / Q000037:antagonists & inhibitors; D016166:Free Radical Scavengers / Q000494:pharmacology; D006801:Humans; D019746:Intramolecular Oxidoreductases / Q000037:antagonists & inhibitors*; D007962:Leukocytes / Q000187:drug effects / Q000201:enzymology; D016859:Lipoxygenase Inhibitors / Q000494:pharmacology*; D008861:Microsomes / Q000201:enzymology*; D062105:Molecular Docking Simulation; D000071876:Prostaglandin-E Synthases; D051636:X-Linked Inhibitor of Apoptosis Protein / Q000037:antagonists & inhibitors
chemical_list: D000893:Anti-Inflammatory Agents; D016588:Anticarcinogenic Agents; D000975:Antioxidants; D016227:Benzoquinones; D015777:Eicosanoids; D016166:Free Radical Scavengers; D016859:Lipoxygenase Inhibitors; D051636:X-Linked Inhibitor of Apoptosis Protein; D001094:Arachidonate 5-Lipoxygenase; D019746:Intramolecular Oxidoreductases; C000605862:PTGES protein, human; D000071876:Prostaglandin-E Synthases; C010945:embelin
keywords: 1-palmitoyl-2-arachidonyl-sn-glycero-3-phosphocholine; 1-palmitoyl-2-oleoyl-sn-glycerol; 5-LO; 5-Lipoxygenase; 5-lipoxygenase; 5-lipoxygenase-activating protein; AA; Ada; Arachidonic acid; COX; DPPH; DTT; Embelin; FLAP; H(P)ETE; HHT; IL; Inflammation; LPS; LT; LUV; Microsomal prostaglandin E(2) synthase-1; N-formyl-methionyl-leucyl-phenylalanine; NO; PAPC; PDB; PG; PGC; PMNL; POG; Protein Data Bank; QPLD; ROS; STI; TNF; X-linked inhibitor of apoptosis protein; XIAP; XP; adenosine desaminase; arachidonic acid; cPLA(2); cyclooxygenase; cytosolic phospholipase A(2); diphenylpicrylhydrazyl radical; dithiothreitol; extra precision; fMLP; hydro(pero)oxyeicosatetraenoic acid; hydroxyheptadecatrienoic acid; interleukin; large unilamellar vesicles; leukotriene; lipopolysaccharide; mPGES-1; microsomal prostaglandin E(2) synthase 1; nitric oxide; phosphate-buffered saline plus 1mg/ml glucose; phosphate-buffered saline plus 1mg/ml glucose and 1mM CaCl(2); polymorphonuclear leukocytes; quantum-mechanics polarized ligand docking; reactive oxygen species; soybean trypsin inhibitor; tumor necrosis factor