title: Different design of enzyme-triggered CO-releasing molecules (ET-CORMs) reveals quantitative differences in biological activities in terms of toxicity and inflammation.
abstract: Acyloxydiene-Fe(CO)3 complexes can act as enzyme-triggered CO-releasing molecules (ET-CORMs). Their biological activity strongly depends on the mother compound from which they are derived, i.e. cyclohexenone or cyclohexanedione, and on the position of the ester functionality they harbour. The present study addresses if the latter characteristic affects CO release, if cytotoxicity of ET-CORMs is mediated through iron release or inhibition of cell respiration and to what extent cyclohexenone and cyclohexanedione derived ET-CORMs differ in their ability to counteract TNF-α mediated inflammation. Irrespective of the formulation (DMSO or cyclodextrin), toxicity in HUVEC was significantly higher for ET-CORMs bearing the ester functionality at the outer (rac-4), as compared to the inner (rac-1) position of the cyclohexenone moiety. This was paralleled by an increased CO release from the former ET-CORM. Toxicity was not mediated via iron as EC50 values for rac-4 were significantly lower than for FeCl2 or FeCl3 and were not influenced by iron chelation. ATP depletion preceded toxicity suggesting impaired cell respiration as putative cause for cell death. In long-term HUVEC cultures inhibition of VCAM-1 expression by rac-1 waned in time, while for the cyclohexanedione derived rac-8 inhibition seems to increase. NFκB was inhibited by both rac-1 and rac-8 independent of IκBα degradation. Both ET-CORMs activated Nrf-2 and consequently induced the expression of HO-1. This study further provides a rational framework for designing acyloxydiene-Fe(CO)3 complexes as ET-CORMs with differential CO release and biological activities. We also provide a better understanding of how these complexes affect cell-biology in mechanistic terms.
authors.affiliation: Institute for Molecular and Cellular Biology, Mannheim University of Applied Sciences, Mannheim, Germany ; Vth. Medical Department, Medical Faculty Mannheim, Ruprecht Karls University, Heidelberg Mannheim, Germany.
authors.forename: E
authors.initials: E
authors.lastname: Stamellou
authors.affiliation: Vth. Medical Department, Medical Faculty Mannheim, Ruprecht Karls University, Heidelberg Mannheim, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Storz
authors.affiliation: Department of Chemistry, University of Cologne, Cologne, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Botov
authors.affiliation: Vth. Medical Department, Medical Faculty Mannheim, Ruprecht Karls University, Heidelberg Mannheim, Germany.
authors.forename: E
authors.initials: E
authors.lastname: Ntasis
authors.affiliation: Vth. Medical Department, Medical Faculty Mannheim, Ruprecht Karls University, Heidelberg Mannheim, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Wedel
authors.affiliation: Department of Chemistry, University of Cologne, Cologne, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Sollazzo
authors.affiliation: Vth. Medical Department, Medical Faculty Mannheim, Ruprecht Karls University, Heidelberg Mannheim, Germany.
authors.forename: B K
authors.initials: BK
authors.lastname: Krämer
authors.affiliation: Department of Nephrology, Academic Medical Center, Groningen, The Netherlands.
authors.forename: W
authors.initials: W
authors.lastname: van Son
authors.affiliation: Department of Nephrology, Academic Medical Center, Groningen, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Seelen
authors.affiliation: Department of Chemistry, University of Cologne, Cologne, Germany.
authors.forename: H G
authors.initials: HG
authors.lastname: Schmalz
authors.affiliation: Department of Chemistry, University of Cologne, Cologne, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Schmidt
authors.affiliation: Institute for Molecular and Cellular Biology, Mannheim University of Applied Sciences, Mannheim, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Hafner
authors.affiliation: Vth. Medical Department, Medical Faculty Mannheim, Ruprecht Karls University, Heidelberg Mannheim, Germany.
authors.forename: B A
authors.initials: BA
authors.lastname: Yard
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D002248:Carbon Monoxide / Q000378:metabolism*; D056831:Coordination Complexes / Q000737:chemistry / Q000633:toxicity*; D003512:Cyclohexanones / Q000737:chemistry / Q000633:toxicity*; D005786:Gene Expression Regulation / Q000187:drug effects; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D007249:Inflammation / Q000378:metabolism* / Q000473:pathology; D058085:Iron Compounds / Q000737:chemistry / Q000633:toxicity*; D051267:NF-E2-Related Factor 2 / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D019010:Vascular Cell Adhesion Molecule-1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D056831:Coordination Complexes; D003512:Cyclohexanones; D058085:Iron Compounds; D051267:NF-E2-Related Factor 2; D016328:NF-kappa B; C495635:NFE2L2 protein, human; D014409:Tumor Necrosis Factor-alpha; D019010:Vascular Cell Adhesion Molecule-1; D002248:Carbon Monoxide
keywords: Adhesion molecules; CO, carbon monoxide; Carbon monoxide; ET-CORM, enzyme-triggered carbon monoxide-releasing molecule; Endothelial cells; Enzyme-triggered CORMs; HO-1, haem oxygenase 1; HUVEC, human umbilical vein endothelial cells; NFκΒ, nuclear factor kappa-light-chain enhancer of activated B-cells; Nrf2, nuclear factor(erythroid-derived); TNF-α, tumour necrosis factor alpha; VCAM-1, vascular cell adhesion molecule 1