Mitochondria-Targeted Compounds - SPARC

Targeting Antioxidants and RedoxProbes to MitochondriaMike MurphyMRC-Dunn Human Nutrition Unit,Cambridge

Mitochondria and Oxidative StressOverviewFirst, the generally recognised consensus on mitochondrialROS production and the critical questions to beaddressed when considering Mitochondria andOxidative Stress

Mitochondria and Oxidative StressOverviewFirst, a generally recognised consensus on mitochondrialROS production and the critical questions to beaddressed when considering Mitochondria andOxidative Stress

Mitochondria and Oxidative StressOverviewFirst, a generally recognised consensus on mitochondrialROS production and the critical questions to beaddressed when considering Mitochondria andOxidative Stress“generally recognised” =“I think, but I haven’t bothered to look up the references”

Critical questions•ROS–Which?–Where?– Effects?

Critical questions• Antioxidants–Which ROS?– Effective?– Other effects?– Measurable endpoints in vivo/patients?

Mitochondrial ROS metabolism

MitoQJBC (2001) 276 4588-4596

JBC (2001) 276 4588-4596Uptake of MitoQ by MitochondriaMitoQ uptake (nmol/mg protein)43210+FCCP0 5 10 15Time (min)

Reduction of MitoQ by the Respiratory ChainTimeAbsorbance= 0.1Wavelength (nm)250 300

Prevention of Lipid Peroxidation by Reduced MitoQ6MDA (nmol/ mg prot ein)5432100 1 5 TPMP 0 1 5[MitoQ] (µM)[Mitoquinone](µM)

Turnover of MitoQ by mitochondria

MitoQ variantsFEBS Letts (2004) 571 9-16

Coenzyme QOHOH 3 COH 3 CO- 2 e -H 3 CO+ 2 e -H 3 COOHnOn

JBC (2005) 280 21295 - 21312

Distribution of MitoQ

Complex III with MitoQ

Could steric hindrance explain the low reactivity of MitoQ 10with Complex III?JBC (2007) in press

Steric inhibition is not involved in Complex III

Complex II with MitoQ10, MitoQ3 and MitoQ5

JBC (2007) in press

Distribution of MitoQ

Annu Rev Pharm Tox (2007) 47 629-656

Potency of MitoQ in a Friedreich‘s Ataxia model120100MitoQMitoQ + FCCPDecylubiquinoneIdebenone8060402000.0001 0.001 0.01 0.1 1 10 100 1000 10000 100000Concentration [nM]FASEB J (2003) 17 1974-1978

Distribution of TPMP in Mice25TPMP (nmol/g wet weight)nnmol TPMP/g wet weight201510500 5 10 15HeartLiverBrainDays of ingestionPNAS (2003) 100, 5407-5412

MitoQ decreases tissue damage during I/R injury

Protection of mitochondrial functionFASEB J (2005) 19 1088-1095

Nitroglycerin tolerance due to damage to mitochondriaControlMitoQNitroglycerinNitroglycerin + MitoQNitroglycerin (log M)Espluges et al (2006) Circ Res 99 1067-1075

Pharmaceutical development of MitoQ• Change counter-ion, complex to β-cyclodextrin• Toxicity– No Observable Effect Level (NOEL) 2.4 mg/kg– No Observable Adverse Effect Level (NOAEL) 10.6mg/kg• Bioavailability ~ 10 %• Minimal excretion in urine of unmodified MitoQ.• Major metabolites in urine - glucuronides on Qring• 10 mg MitoQ tablets

Plasma levels of MitoQ in humansfollowing oral administration[MitoQ] (ng/ml)45403530252015MitoQ (1 mg/kg oral)C max = 33.15 ng/mlT max = 1 hourMean ± SD, N = 610500 2 4 6 8 10 12Time (hour)

Human Phase II trials with MitoQ(Antipodean Pharmaceuticals Incwww.antipodeanpharma.com)• Parkinson’s Disease “Protect Trial”– A double-blind, prospective, randomized comparison of 2 doses of MitoQ (40 and 80 mg) andplacebo for the treatment of patients With Parkinson’s Disease– Primary outcome: Unified Parkinson's Disease Rating Scale (UPDRS) score at the final studyvisit compared to baseline– Multi centre (New Zealand and Australia), fully recruited (128 patients), outcome due March2008.• Hepatitis C– Phase II clinical trial of MitoQ to investigate the drug’s efficacy to reduce liver damage inpatients with raised liver enzymes associated with the Hepatitis C virus (HCV).– Auckland, NZ. Started recruiting February 2007