Design and Development of Superoxide Dismutase Mimetics as
Transcription
Design and Development of Superoxide Dismutase Mimetics as
Design and Development of Superoxide Dismutase Mimetics as Therapeutics Traditional Approach Block negative effects of enzymes A B MetaPhore’s Approach Amplify positive effects of enzymes C D SYNZYMES: A CASE STUDY Mimics of Superoxide Dismutase : mSOD Superoxide Shunts HOO. H+ SOD Catalyst Normal Hydrogen Peroxide Detoxification O2-. Neutrophil-Driven Immune Responses O2 + H2O2 Catalase or Glutathione Peroxidase O2 + H2O (Myeloperoxidase) + Cl- OCl- - bacteriocide Reactive Oxygen Metabolites HOO Lipids, DNA, Catecholamines, Steroids, etc. . H+ Arginine -. O2 SOD Catalyst FeIII NO. NOS OONO- Storage Proteins O2 + H2O2 Chain Autoxidation Products Fe H+ II [OONOH] . OH (Hydroxyl Radical) Cellular Damage Peroxynitrite Cytotoxic NO2. Biochemical Impact of Excess Superoxide Anions DNA Damage Degrades Synovial Fluid & Collagen Depolymerize Hyaluronic Acid – O2 Cytokine Release ONOO– Generation Lipid Peroxidation Stimulates Release of Inflammatory Mediators Superoxide is eliminated under physiological conditions by a set of superoxide dismutase enzymes that convert it to hydrogen peroxide which is then converted to water and oxygen by catalase. Mangenese superoxide dismutase is localized in mitochondria while Cu/Zn superoxide dismutases are in the cytoplasm and extracellular. Bovine Cu/Zn SOD (Orgatein®) was used as a pharmaceutical in Europe for many years for the treatment of osteoarthritis. In animal models, SOD enzymes have been shown efficacious in models of ischemia-reperfusion injury, inflammation, radiation damage, etc. DISADVANTAGES OF PROTEIN SOD THERAPY Lack of Oral Activity Lack of Access to Intracellular Space where Superoxide is Produced Immunogenicity Short Half-Lives in Serum Project Goal: SOD mimics To develop a revolutionary advance in the small molecule approach to pharmacological intervention. Ribbon diagram of crystal structure of human superoxide dismutase dimer; active sites are within blue ribbons Enzyme Mimetic confidential TECHNOLOGY: mSODs 10 years of research >$50 Million SOD • • • 88kDA kcat = 108-109 M-1s-1 superoxide hydrogen peroxide mSOD •ca. 500Da •kcat = 107-109 M-1s-1 •superoxide hydrogen peroxide N H Cl N N Mn N Cl N H H M40403 H D. P. Riley and R. H. Weiss, J. Am. Chem. Soc. 116:387-388, 1994 Stopped-Flow UV Assay for SOD Mimetics D. P. Riley and R. H. Weiss, J. Am. Che Soc. 116:387-388, 1994 Traditional Approach to Synthesis of Pentaazacrowns Gave Poor Yields Cyclic Peptide Approach to Cyclopentaazacrowns Aston et al. Tetrahedron Lett. 35:3687, 1994 SOD Mimetics Used to Develop Models of Mechanisms Changes in Chirality of Substituents and Introduction of Cyclic Constraints Modified Complex Geometry D. P. Riley, Susan L. Henke, Patrick J. Lennon and Karl Aston, Inorg. Chem. 38:1908-1917, 1999 Stereochemical Effects H H N N Cl N Mn Cl N H N H H H all-Rkcat (pH=7.4)= 1.2 x 10+8 M-1 s-1 H N N Cl N Mn Cl H N N H H R,R,S,Skcat (pH=7.4): Inactive R,R,S,S,-isomer is rigidly planar; i.e., will not fold, thus no catalytic activity Ligands Used to Test Predictive Ability of Model Mn(II): E = 32.2 kcal Mn(III): 31.0 kcal The folded six-coordinate Mn(II) structure is very close to that of the sixcoordinate Mn(III) indicating a favorable geometry for facile electron transfer & hence fast SOD catalysis. (Science, 286, 304 (1999)). MECHANISMS FOR CONVERSION OF SUPER-OXIDE TO HYDROGEN PEROXIDE VIA INNER SPHERE OR OUTER SHERE OXIDATION OF MN(II) D. P. Riley, Susan L. Henke, Patrick J. Lennon and Karl Aston, Inorg. Chem. 38:1908-1917, 1999 H N H Cl N Mn HN Cl N H SC-68328 CH3 CH3 NH 6000-fold stability increase, while retaining catalytic activity N HN Cl N Mn N H Cl N H M40403 H Synthesis of M40403 NH2 1. TrtCl, CH2Cl2 N 2. Glyoxal, MeOH NH2 H2/Pd on C N CH3OH NHTrt TrtHN 96% NH HN NHTrt TrtHN 100% conc. HCl TrtCl 96% OHC N NH CHO HN •4HCl + NH2 + MnCl2 H2N M40400 H N N Cl N Mn Cl Pd/C, 150 psig H2 ropanol H2 H H N N H 1 hr, >98% yield N N Cl N Mn Cl N M40402 Intermediate M40403 H N H 99.3% purity in 1 pot reaction->93% Chem Yield with No Chromatography or Crystallization needed H Cl N H N Mn Cl H H N Cl N N N H H N Cl S M40403 Mn N Cl N N N S M40401 *Riley, et.al, Inorg. Chem., 2001, 40(8), 1779. H H H H N N Mn Cl S H N M40484 N S H Chemical History of SODm SAR studies utilizing the [Mn([15]aneN5)Cl2] lead reveals that extremely high chemical stability is achieved with added substituents to carbon centers of the macrocyclic ligand (Inorg.Chem.,35, 5213, 1996) SAR studies reveal that catalytic activity can be dramatically affected with the stereochemistry, number, and position of such substituents (JACS, 119, 995 (1997)). Mechanistic understanding developed that led to a molecular modeling paradigm (MM) allowing prediction of catalytic activity (Inorg. Chem., 38, 1908 (1999); and ibid., 40(8), 1779 (2000).) Bis-cyclohexylpyridine class of SOD mimic affords high activity and high stability with excellent in vivo efficacy (Science, 286, 304 (1999)). Metabolism of M40403 H H 3 H N N Cl N Mn Cl H N N H Liver Oxidases H H 3 N N Cl N Mn Cl H N N H M40403 M40414 kcat (pH=7.4) = 1.6 x 10+7 kcat (pH=7.4) = 1.35 x 10+7 log P = -0.3 log P = -0.9 H H N N Cl N Mn Cl N H N isomer Native Enzyme M40403 One of two subunits. – Inflammation O2 Cardiovascular/CNS Ischemia-reperfusion injury Septic shock Organ transplantation Stroke Pain IBD/Crohn’s Oncology Osteoarthritis Rheumatoid arthritis Pain Psoriasis Inhibition of tumor growth Reduction of side effects associated with chemotherapy and radiation therapy Superoxide – central role SOD mimetics effective in multiple models Rheumatoid arthritis Blocks TNF release Asthma Many diseases severe/ chronic Pain Persist j acu / mod PAIN Traditional NSAIDs provide unsatisfactory relief in models of severe chronic pain (neuropathic pain, visceral pain, cancer pain) Opportunities exist beyond opioids and NSAIDs for the treatment of acute and severe pain Roles of Superoxide Anions (O2 •) in Pain Damage nerve endings Direct algesic action Sensitize primary afferent neurons – O2 Increase spinal release of excitatory amino acids (NMDA) Deactivate NE, a potent endogenous analgesic Superoxide anions 9 Decomposed Superoxide anions Vehicle 8 7 SOD-PEG 6 5 4 3 2 1 0 0 50 100 150 200 Latency changes (sec.) Latency changes (sec.) 10 Superoxide anions 10 M40403(6mpk) M40403(3mpk) 8 M40403(1mpk) 6 4 2 0 0 50 Time (min) post superoxide anion 100 150 M40404 which lacks SODm activity does not block this response. Drugs given i.v. 15min before challenge 200 % inhibition of hyperalgesia Rapid onset Long duration 0 0 25 25 50 50 75 75 100 0 10 20 30 40 50 60 100 vehicle 1 mg/kg 3 mg/kg 6 mg/kg 0 Time (min) post drug drug administered iv 3 hr after carrageenan 1 2 3 4 5 6 Time (hr) post drug 7 M40403 Restores Analgesia in Morphine-tolerant Mice 120 80 Compound given 5 min prior to morphine 60 40 0.03 0.01 Tol 0 mg/kg, i.v 1 20 Naive % Analgesia 100 Mechanism: SOD-mimics in Ischemia – Reperfusion-Mediated Injury Ischemia Reperfusion - O2 Lipid peroxidation & cellular damage TNF Neutrophil activation/ sequestration Primary & Secondary Organ Damage O-2 concentration 0 Control I (30min) I+R (60s) +SC-67066 (0.65mol/kg) +SC-67066(1.25mol/kg) +SC-67066(2.5mol/kg) +SC-65512(2.5mol/kg) 10 20 . HO2 . H2O2 Initiation HO . OH HO2 O2 O Propagation O OH O OH HO NHR HO NHR R=H, Norepinephrine R=Me, Epinephrine RHN . "Quinone" OONOStoichiometric . oxidation O . A Single Reaction with HO2 Initiates a - "Chain Autoxidation" Affording Multiple Conversions to "Adrenochromes"! OH O + N Polymerize R "Adrenochromes" Crosslinked Proteins Cytotoxic Melanin Salvemini, MacArthur, Riley, PNAS, 2000, 97(17), 9753 MetaPhore Pharmaceuticals PAC Conformational Template vs. Type I -Turn Pentaazacrown complexed with Mn(II, red ball) showing overlap of i, i+1, and i+2 side-chain orientations (yellow) Arg Asp Tyr T r Arg Arg Tyr Trp MAC TENDAMISTAT T ND M ST T MIMICRY OF CHIRAL MAC WITH WRY SEQUENCE OF TENDAMISTAT THAT INHIBITS -AMYLASE Trp Entropy and Solvation 1. Lafont, V., A.A. Armstrong, H. Ohtaka, Y. Kiso, L. Mario Amzel, and E. Freire, Compensating enthalpic and entropic changes hinder binding affinity optimization. Chem Biol Drug Des, 2007. 69(6): p. 413-22. 2. Young, T., R. Abel, B. Kim, B.J. Berne, and R.A. Friesner, Motifs for molecular recognition exploiting hydrophobic enclosure in protein-ligand binding. Proc Natl Acad Sci U S A, 2007. 104(3): p. 808-13. Enzyme Mimetic Structured Waters