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Protection against doxorubicin-induced cardiotoxicity by ICRF-187 (Dexrazoxane)
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Session 6: Development of Antioxidant Pharmaceuticals COMPARATIVE STUDIES ON THE ANTIOXIDANT PROPERTIES OF CGP 2881 AND PROBUCOL IN V/LDL ISOLATED FROM CHOLIC ACIDFED RATS. Kenneth S. Leonards. Chii-Whei Hu, Wilbur K. Sawyer, and Margaret F. Prescott Research Dept , Pharma. Div Ciba-Geigy Corp., Summit, New Jersey, 07901 USA Mechanistic studies on the antioxidant properties of CGP 2881 and Probucol in V/LDL were conducted to better understand the molecular processes involved. Cholic acid rats were treated for five days (50 mg/kg po) with vehicle, CGP 2881, or Probucol The V/LDL was isolated and analyzed by HPLC to quantify the concentrations of the parent compound and metaboliteioxidation products in the V/LDL. In addition, the fatty acid compositions of the phosphatidylcholine (PC), triglyceride (TG), and cholesterol ester (CE) fractions of the V/LDL were analyzed by gas chromatography to determine the effects of compound treatment on lipid composition. Studies were also conducted 10 examine the effects of ex viva Cu2+ oxidation on these parameters in the V/LDL from each treatment, and to ascertaIn the protective capacities of CGP 2881 and Probucol in the V/LDL particles under these conditions. Results of these studies indicate that the average concentration of CGP 2881 in the V/LDL was 14-15 molecules per particle, compared to 6-7 for Probucol. Results from the Cu2+ oxidation experiments demonstrated that CGP 2881, but not Probucol, completely protected the V/LDL from oxidation over a 22 hr incubation period. FAME analysis of the PC, CE, and TG fractions after Cu2+ oxidation also showed that the primary target of oxidative attack was arachidonic acid (C20:4) in the PC and CE fractions, followed by linoleic acid (C18:2) oxidation Analysis of the oxidation pattern suggests that CGP 2881 is preferentially associated with the phospholipid coat of the ViLDL particle, and that this partially explains the increased potency of CGP 2881 over Probucol as an antioxidant.
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PROTECTIVE EFFECT OF THE 21-AMINOSTEROID DRUG (U74389F) AGAINST HYPEROXIC INHIBITION OF NORMAL NEWBORN RAT LUNG DEVELOPMENT Lee Frank and Gwenn E. McLaughlin, Departments of Medicine & Pediatrics, Pulmonary University of Miami School of Research Center, Medicine, Miami, Florida, 33101 USA. We tested the possible protective effect of a potent lipophilic FeU74389F (reportedly anti-lipid peroxidation agent) chelator and inhibition of normal lung against Oz-induced newborn rat alveolarization in PUPS. BY after 10 days in >95% 0: morphometric analysis, the U74389F-treated pups (15mg/kg/d) had reduced diameter) and increased ISA Lh, (mean airspace area for respiratory (lung internal surface the 0: control rat pups: exchange) vs. ISA(cm') Treatment Lt.&J&!!l 1014 Air Groups 47.4 61.0 (729%)* 769 (124%)* 0,-contrdls 919 (1 9%)+ 53.4 (t13%)*+ 01-U74289F [(n) = 12/group; *p
CGP 2881 INHIBITS THE DENSITY LIPOPROTEINS.
T.C.
M.F. Ciba
OXIDATION OF D.L. Feldman,
LOW
6:lO
Mogelesky, R. Sharif, W.K. Sawyer, Prescott. Research Department, Geigy Corp., Summit, N.J. 07901.
The oxidation of low density lipoproteins (LDL) appears to have an important role in atherogenesis. The hypolipidemic/antioxidant probucol (PRO) protects LDL from oxidation and inhibits the formation of experimental atherosclerotic lesions. CGP 2881 is a structural analogue of PRO and displays antioxidant properties that are simila $+to PRO. CGP 2881 (1 uM) inhibited Cu -induced oxidation of LDL (assessed by delay in lag phase for conjugated diene formation) by 3.9 fold vs vehicle. When 5 uM CGP 2881 was pfeincorporated into LDL prior to Cu oxidation, the lag phase was potently delayed vs vehicle. CGP 2881 also inhibited
macrophage-induced
oxidation
of
(assessed by formation of TBARS) with an IC50 = 0.64 uM. LDL isolated from hypercholesterolemic rats and rabbits which had been treated with 50 mg/kg CGP 2881 for 5 days was protecteq+from ex vivo oxidation induced by Cu (rats = 3.5 fold; rabbits = 7.7 fold) and by macrophages (rabbits = 93%). CGP 2881 activity will be compared to reference antioxidants. LDL
DOXORUBICIN-INDUCED AGAINST PROTECTION CARDIOTOXICITY BY ICRF-187 (DEXBAZOXANEI Brian B. Hasinoff Faculty of Pharmacy, University Manitoba R3T 2N2, Canada.
of
Manitoba,
Winnipeg,
The bisdioxopiperazine ICRF-187, which is currently in phase III clinical trials, is highly effective in preventing doxorubicininduced cardiotoxicity. ICRF-187 likely acts by diffusing into the cell, hydrolyzing to its metal-ion binding form and chelating free iron or iron bound to the iron-doxorubicin complex, preventing iron-based oxygen radical production. Upon full hydrolysis ICRF-187 undergoes ring-opening to ADR-925, an EDTA-type structure that strongly binds metal ions.
ICRF-187
ADR-925
The hydrolysis products of ICRF-187 have been shown to protect against iron-doxorubicin induced inactivation of both cytochrome c oxidase and NADH cytochrome c reductase on submitochondrial particles. The hydrolysis products of ICRF187 are able to slowly remove iron from ferritin and transferrin The slow ring-opening and copper from ceruloplasmin. hydrolysis of ICRF-187 to its metal-ion binding forms has been The enzymatic under physiological conditions. studied hydrolysis of ICRF-187 and its (-j(R) optical isomer ICRF-186 in isolated liver cells and by purified dihydropyrimidine amidohydrolase has also been characterized. This work has been supported by grants from the Medical Research Council and the Natural Sciences and Engineering Research Council.
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Session 6: Development of Antioxidant Pharmaceuticals COMPARATIVE STUDIES ON THE ANTIOXIDANT PROPERTIES OF CGP 2881 AND PROBUCOL IN V/LDL ISOLATED FROM CHOLIC ACIDFED RATS. Kenneth S. Leonards. Chii-Whei Hu, Wilbur K. Sawyer, and Margaret F. Prescott Research Dept , Pharma. Div Ciba-Geigy Corp., Summit, New Jersey, 07901 USA Mechanistic studies on the antioxidant properties of CGP 2881 and Probucol in V/LDL were conducted to better understand the molecular processes involved. Cholic acid rats were treated for five days (50 mg/kg po) with vehicle, CGP 2881, or Probucol The V/LDL was isolated and analyzed by HPLC to quantify the concentrations of the parent compound and metaboliteioxidation products in the V/LDL. In addition, the fatty acid compositions of the phosphatidylcholine (PC), triglyceride (TG), and cholesterol ester (CE) fractions of the V/LDL were analyzed by gas chromatography to determine the effects of compound treatment on lipid composition. Studies were also conducted 10 examine the effects of ex viva Cu2+ oxidation on these parameters in the V/LDL from each treatment, and to ascertaIn the protective capacities of CGP 2881 and Probucol in the V/LDL particles under these conditions. Results of these studies indicate that the average concentration of CGP 2881 in the V/LDL was 14-15 molecules per particle, compared to 6-7 for Probucol. Results from the Cu2+ oxidation experiments demonstrated that CGP 2881, but not Probucol, completely protected the V/LDL from oxidation over a 22 hr incubation period. FAME analysis of the PC, CE, and TG fractions after Cu2+ oxidation also showed that the primary target of oxidative attack was arachidonic acid (C20:4) in the PC and CE fractions, followed by linoleic acid (C18:2) oxidation Analysis of the oxidation pattern suggests that CGP 2881 is preferentially associated with the phospholipid coat of the ViLDL particle, and that this partially explains the increased potency of CGP 2881 over Probucol as an antioxidant.
6:ll
PROTECTIVE EFFECT OF THE 21-AMINOSTEROID DRUG (U74389F) AGAINST HYPEROXIC INHIBITION OF NORMAL NEWBORN RAT LUNG DEVELOPMENT Lee Frank and Gwenn E. McLaughlin, Departments of Medicine & Pediatrics, Pulmonary University of Miami School of Research Center, Medicine, Miami, Florida, 33101 USA. We tested the possible protective effect of a potent lipophilic FeU74389F (reportedly anti-lipid peroxidation agent) chelator and inhibition of normal lung against Oz-induced newborn rat alveolarization in PUPS. BY after 10 days in >95% 0: morphometric analysis, the U74389F-treated pups (15mg/kg/d) had reduced diameter) and increased ISA Lh, (mean airspace area for respiratory (lung internal surface the 0: control rat pups: exchange) vs. ISA(cm') Treatment Lt.&J&!!l 1014 Air Groups 47.4 61.0 (729%)* 769 (124%)* 0,-contrdls 919 (1 9%)+ 53.4 (t13%)*+ 01-U74289F [(n) = 12/group; *p
CGP 2881 INHIBITS THE DENSITY LIPOPROTEINS.
T.C.
M.F. Ciba
OXIDATION OF D.L. Feldman,
LOW
6:lO
Mogelesky, R. Sharif, W.K. Sawyer, Prescott. Research Department, Geigy Corp., Summit, N.J. 07901.
The oxidation of low density lipoproteins (LDL) appears to have an important role in atherogenesis. The hypolipidemic/antioxidant probucol (PRO) protects LDL from oxidation and inhibits the formation of experimental atherosclerotic lesions. CGP 2881 is a structural analogue of PRO and displays antioxidant properties that are simila $+to PRO. CGP 2881 (1 uM) inhibited Cu -induced oxidation of LDL (assessed by delay in lag phase for conjugated diene formation) by 3.9 fold vs vehicle. When 5 uM CGP 2881 was pfeincorporated into LDL prior to Cu oxidation, the lag phase was potently delayed vs vehicle. CGP 2881 also inhibited
macrophage-induced
oxidation
of
(assessed by formation of TBARS) with an IC50 = 0.64 uM. LDL isolated from hypercholesterolemic rats and rabbits which had been treated with 50 mg/kg CGP 2881 for 5 days was protecteq+from ex vivo oxidation induced by Cu (rats = 3.5 fold; rabbits = 7.7 fold) and by macrophages (rabbits = 93%). CGP 2881 activity will be compared to reference antioxidants. LDL
DOXORUBICIN-INDUCED AGAINST PROTECTION CARDIOTOXICITY BY ICRF-187 (DEXBAZOXANEI Brian B. Hasinoff Faculty of Pharmacy, University Manitoba R3T 2N2, Canada.
of
Manitoba,
Winnipeg,
The bisdioxopiperazine ICRF-187, which is currently in phase III clinical trials, is highly effective in preventing doxorubicininduced cardiotoxicity. ICRF-187 likely acts by diffusing into the cell, hydrolyzing to its metal-ion binding form and chelating free iron or iron bound to the iron-doxorubicin complex, preventing iron-based oxygen radical production. Upon full hydrolysis ICRF-187 undergoes ring-opening to ADR-925, an EDTA-type structure that strongly binds metal ions.
ICRF-187
ADR-925
The hydrolysis products of ICRF-187 have been shown to protect against iron-doxorubicin induced inactivation of both cytochrome c oxidase and NADH cytochrome c reductase on submitochondrial particles. The hydrolysis products of ICRF187 are able to slowly remove iron from ferritin and transferrin The slow ring-opening and copper from ceruloplasmin. hydrolysis of ICRF-187 to its metal-ion binding forms has been The enzymatic under physiological conditions. studied hydrolysis of ICRF-187 and its (-j(R) optical isomer ICRF-186 in isolated liver cells and by purified dihydropyrimidine amidohydrolase has also been characterized. This work has been supported by grants from the Medical Research Council and the Natural Sciences and Engineering Research Council.
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