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Learn about the development, properties, and pharmacokinetics of metalloenzyme mimetics as potent antioxidants in combating various pathologies and promoting overall well-being. Discover their efficacy in attenuating injuries, preventing peroxide formation, scavenging radicals, and their potential impacts on different organs. Explore their toxicity and mechanisms in enhancing antioxidant activity. Stay informed on the latest advancements in antioxidant research.
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Sunrise Free Radical School Redox, Kinetic, and Biological Necessities to Create an Effective Metalloenzyme-mimetic James D. Crapo, M.D.
Free Radical-Mediated Pathologies • Normal Metabolism, Aging • Chemical • Hyperoxia • Ischemia-Reperfusion • Inflammation • Autoimmune • Cancer
Antioxidants Efficiency a Tocopherol Non Enzymatic Ascorbate 1 β Carotene NAC Enzymatic Superoxide Dismutases Catalase 1,000 – 10,000 Metalloenzyme Mimetics 1,000 – 10,000 Mimetics
+ N N N N N + Mn N N N N N N O O + M n Mn + + N N N N N N C H O O C H 3 3 Salen Mimetic Macrocylic Mimetic [EUK-134] [M-40403] N N + meso-Porphyrin Mimetic Several Classes of Catalytic Antioxidants
The Redox Potentials for the Half Reactions of the Dismutation of Superoxide and Superoxide Dismutases E 1/2 (NHE) -0.33 +0.94 +0.3 O2-. O2 + e- O2-. + 2H+ + e- H2O2 MnSOD CuZnSOD 2O2-. + 2H+ H2O2
Metalloporphyrin Antioxidant MimeticsEfficacy of First Generation - TBAP Cardiovascular Cardiomyopathy Zymoson-Induced Shock Joint Carregeenin Paw Edema Lung Paraquat Injury Carregeenin Inflammation Bleomycin-Induced Fibrosis CNS Kainate-Induced Seizures Cerebral Vasoconstriction Spinal Cord Injury Liver Ischemia-Reperfusion Steatosis Acetaminophine Injury Fas-Mediated Acute Injury
R N N + Mn R R N N R Development of an Antioxidant Mimetic Modify side chains Modify charge Modify redox potential Alter backbone Change metal Aeol-10150
Metals • Manganese • Iron • Copper • Cobalt • Nickel
The Redox Potentials for the Half Reactions of the Dismutation of Superoxide and Superoxide Dismutases E 1/2 (NHE) -0.33 +0.94 -0.23 +0.06 +0.3 O2-. O2 + e- O2-. + 2H+ + e- H2O2 MnTMPyP MnSOD CuZnSOD MnTBAP 2O2-. + 2H+ H2O2
+ R , , , = N C H 1 2 3 4 3 R R 2 1 N R , , , = 1 2 3 4 N Mn N N + C H 3 N R R 3 4 R , , , = 1 2 3 4 N + H C 3 The “Ortho Effect” SOD Activity units/mg 225 336 10,648
N + N N + N + Mn N + N N + N MN TE-2-PyP Molecular Formula: C48H56N8Cl5Mn Molecular Weight: 977 5Clˉ
Antioxidant Activities Lipid ONOO SOD peroxidation scavenger Catalase (U/mg) IC50 (M) (M-1S-1) % activity CuZn SOD 5,100 15 — — Mn TBAP 179 29 3.0x105 0.42 Mn TM-4-PyP 550 16 1.8x108 0.45 MnTE-2-PyP 8,500 1 1.0x107 1.41
Antioxidant Activities Lipid ONOO SOD peroxidation scavenger Catalase (U/mg) IC50 (M) (M-1S-1) % activity CuZn SOD 5,100 15 — — Mn TBAP 179 29 3.0x105 0.42 Mn TM-4-PyP 550 16 1.8x108 0.45 MnTE-2-PyP 8,500 1 1.0x107 1.41 MnTM-2,5-IP 14,800 1 1.0x106 1.67
The Redox Potentials for the Half Reactions of the Dismutation of Superoxide and Superoxide Dismutases E 1/2 (NHE) MnTE-2-PyP MnTM-2,5-IP -0.33 +0.94 -0.23 +0.06 +0.3 +0.23 +0.33 O2-. O2 + e- O2-. + 2H+ + e- H2O2 MnTMPyP MnSOD CuZnSOD MnTBAP 2O2-. + 2H+ H2O2
Antioxidant Properties of Metalloenzyme Mimetics • Attenuate O2- Mediated Injury • Attenuate H2O2 Mediated Injury • Prevent Formation of Lipid Peroxides • Scavenge ONOO-
Pharmacokinetics • Route • Uptake • Distribution • Half Life • Plasma • Tissue
Mouse Plasma Concentrations ofMnTM-2,5-IP (iv bolus) 100000 T ~44 minutes 1/2 10000 1000 MnTM-2,5-IP (ng/ml) 30mg/kg 100 10mg/kg 3mg/kg 10 1mg/kg 1 0 1 2 3 4 5 6 7 Hours
MnTM-2,5-IP Steady-State From Mini-Osmotic Pump (1.12 mg/kg loading dose followed by 1.8 mg/kg/hr infusion for 24 hours) Steady-State 1000000 (ng/g or ng/ml) kidney 34,100 liver 16,300 10000 MnTM-2,5-IP serum 2,000 (ng/g or ng/ml) lung 1,600 heart 1,000 100 brain 90 1 0 4 8 12 16 20 24 Hours
MnTM-2,5-IP Clearance from Mini-Osmotic Pump(1.12 mg/kg loading dose followed by 1.8 mg/kg/hr infusion for 24 hours) 1000000 estimated half-life (hrs) kidney 140 10000 liver 136 MnTM-2,5-IP (ng/g or ng/ml) lung 83 heart 96 100 brain 49 serum 8 1 0 24 48 72 96 Hours
Pharmacokinetics of MnTM-2,5-IP in Rats(24 mg/kg, SC) T ~ 3 hrs 100000 1/2 Time to peak ~ 6 hrs Effective dosing interval ~ 9 hrs Plasma MnTM-2,5-IP (ng/ml) 10000 1000 0 2 4 6 8 10 12 14 Hours
Toxicity • MTD • Organ specific • Mutagenicity • Cardiovascular
Mechanisms • Antioxidant - targeted
CuZn SOD Concentrations in Hepatocyte Organelles Organelles mg SOD/cm3 Nucleus 0.71 ± 0.06 Cytoplasmic Matrix 1.36 ± 0.30 Mitochondria 0.21 ± 0.01 RER 0 SER 0.02 ± 0.01 Golgi Apparatus 0 Lysosomes 5.81 ± 1.55 Peroxisomes 0.27 ± 0.08
Distribution of CuZn SOD Molecules in Hepatocyte Organelles Organelles # μm3 Nucleus 13,300 Cytoplasmic Matrix 25,500 Mitochondria 3,900 SER 400 Lysosomes 108,900 Peroxisomes 5,000
800 700 600 500 400 Units/g lung 300 200 100 0 CuZn SOD Mn SOD EC-SOD Human SOD Total Activity in Lung
50 45 40 35 30 Units/cm3 tissue 25 20 15 10 5 0 CuZn SODin Cells MnSOD inMitochondria EC-SOD inInterstitium SOD Activities in Specific Compartments
2500 9000 8000 2000 7000 6000 1500 Units/g wet weight 5000 Units/g wet weight 4000 1000 3000 500 2000 1000 0 0 Liver Kidney Heart Brain Lung Liver Kidney Brain Heart Lung Human Human A B CuZn SOD Mn SOD
EC-SOD 600 500 400 Units/g wet weight 300 200 100 0 Liver Kidney Heart Brain Lung Human
Estimated AOE in 70 Kg Human • CuZn SOD – 10-20 gm • Mn SOD 5-10 gm • EC-SOD 1-2 gm
Mechanisms • Antioxidant - targeted • NFκB inhibition
NF-κB • Nuclear Factor-Kappa B • First discovered as an enhancer of B cells (Sen & Baltimore 1986, Cell) • Ubiquitous transcription factor • Shown to be involved in cancer, immune response, redox regulation, apoptosis
NF-κB Pathway Adapted from: www.emdbiosciences.com/html/CBC/NFKB_NFkappaB_IKB_IKK_Pathway_Products.htm