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Zhang Y, Dai X, Wang J, Liang J, Rabeah J, Tian X, Yao X, Wang Y, Pang S. In Situ-Generated Cu I Catalytic System for Oxidative N-Formylation of N-Heterocycles and Acyclic Amines with Methanol. CHEMSUSCHEM 2023; 16:e202202104. [PMID: 36478405 DOI: 10.1002/cssc.202202104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 12/06/2022] [Indexed: 06/17/2023]
Abstract
The development of a sustainable and simple catalytic system for N-formylation of N-heterocycles with methanol by direct coupling remains a challenge, owing to many competing side reactions, given the sensitivity of N-heterocycles to many catalytic oxidation or dehydrogenation systems. This work concerns the development of an in situ-generated CuI catalytic system for oxidative N-formylation of N-heterocycles with methanol that is based on the case study of a more typical 1,2,3,4-tetrahydroquinoline as substrate. Aside from N-heterocycles, some acyclic amines are also transformed into the corresponding N-formamides in moderate yields. Furthermore, a probable reaction mechanism and reaction pathway are proposed and extension of work based on some findings leads to a demonstration that the formed ⋅O2 - and ⋅OOH radicals in the catalytic system is related to the formation of undesired tar-like products.
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Affiliation(s)
- Yujing Zhang
- Key Laboratory of Eco-functional Polymer Materials of the Ministry of Education, Key Laboratory of Polymer Materials of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, 730070, Lanzhou, Gansu, P. R. China
| | - Xingchao Dai
- Leibniz-Institut für Katalyse e.V. an der Universität Rostock (LIKAT), Albert-Einstein-Str. 29a, 18059, Rostock, Germany
| | - Jixue Wang
- Key Laboratory of Eco-functional Polymer Materials of the Ministry of Education, Key Laboratory of Polymer Materials of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, 730070, Lanzhou, Gansu, P. R. China
| | - Junxi Liang
- Chemical Engineering Institute, Key Laboratory of Environment-Friendly Composite Materials of the State Ethnic Affairs Commission, Northwest Minzu University, 730030, Lanzhou, Gansu, P. R. China
| | - Jabor Rabeah
- Leibniz-Institut für Katalyse e.V. an der Universität Rostock (LIKAT), Albert-Einstein-Str. 29a, 18059, Rostock, Germany
| | - Xia Tian
- Key Laboratory of Eco-functional Polymer Materials of the Ministry of Education, Key Laboratory of Polymer Materials of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, 730070, Lanzhou, Gansu, P. R. China
| | - Xiaoqiang Yao
- Key Laboratory of Eco-functional Polymer Materials of the Ministry of Education, Key Laboratory of Polymer Materials of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, 730070, Lanzhou, Gansu, P. R. China
| | - Yanbin Wang
- Chemical Engineering Institute, Key Laboratory of Environment-Friendly Composite Materials of the State Ethnic Affairs Commission, Northwest Minzu University, 730030, Lanzhou, Gansu, P. R. China
| | - Shaofeng Pang
- Chemical Engineering Institute, Key Laboratory of Environment-Friendly Composite Materials of the State Ethnic Affairs Commission, Northwest Minzu University, 730030, Lanzhou, Gansu, P. R. China
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Landino LM, Shuckrow ZT, Mooney AS, Lauderback CO, Lorenzi KE. Photo-oxidation and Photoreduction of Catechols by Chlorophyll Metabolites and Methylene Blue. Chem Res Toxicol 2022; 35:1851-1862. [PMID: 36044382 DOI: 10.1021/acs.chemrestox.2c00142] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
While plant-derived oxidants can protect cells from oxidative damage, limited research has examined the role of dietary chlorophyll. Photoreduction of ubiquinone by chlorophyll metabolites and red light has been reported in vitro and in animal models. Herein we examined photo-oxidation and photoreduction reactions of catechols, dopamine and hydrocaffeic acid. Photo-oxidation of dopamine by methylene blue and the chlorophyll metabolites pheophorbide A, chlorin e6 and sodium copper chlorophyllin was studied by monitoring aminochrome, the cyclized product of the dopamine o-quinone with its amine. Singlet oxygen scavengers including sodium azide, ascorbate and glutathione decreased aminochrome formation by methylene blue and pheophorbide A. Addition of EDTA, a tertiary amine electron donor, to the reaction of dopamine, photosensitizer and red light decreased aminochrome formation. Photoreduction of the dopamine o-quinone produced by mushroom tyrosinase was achieved by both methylene blue and pheophorbide A only when an electron donor was included. Due to limited solubility, photo-oxidation and photoreduction reactions by pheophorbide A required 5-7.5% dimethylformamide for optimal reactivity. Catalytic photoreduction of 2,3-dimethoxy-5-methyl-p-benzoquinone by methylene blue or pheophorbide A and tertiary amine electron donors was observed. Among the chlorophyll metabolites, pheophorbide A was more effective than chlorin e6 or sodium copper chlorophyllin in photo-oxidation of dopamine and photoreduction reactions. Singlet oxygen inhibited lactate dehydrogenase A activity, and higher molecular weight protein cross-links were observed on SDS-PAGE. Hydrocaffeic acid competed with lactate dehydrogenase A for reaction with singlet oxygen produced by methylene blue; however, no protection by hydrocaffeic acid (HCA) was observed when pheophorbide A was used. Cysteine modification of lactate dehydrogenase A by the o-quinone of hydrocaffeic acid was detected using a redox cycling stain. Inclusion of an electron donor decreased protein labeling.
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Affiliation(s)
- Lisa M Landino
- Department of Chemistry, William and Mary, P.O. Box 8795, Williamsburg, Virginia 23187-8795, United States
| | - Zachary T Shuckrow
- Department of Chemistry, William and Mary, P.O. Box 8795, Williamsburg, Virginia 23187-8795, United States
| | - Alexander S Mooney
- Department of Chemistry, William and Mary, P.O. Box 8795, Williamsburg, Virginia 23187-8795, United States
| | - Clare O Lauderback
- Department of Chemistry, William and Mary, P.O. Box 8795, Williamsburg, Virginia 23187-8795, United States
| | - Kristen E Lorenzi
- Department of Chemistry, William and Mary, P.O. Box 8795, Williamsburg, Virginia 23187-8795, United States
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Kloer HU, Belardinelli R, Ruchong O, Rosenfeldt F. Combining Ubiquinol With a Statin May Benefit Hypercholesterolaemic Patients With Chronic Heart Failure. Heart Lung Circ 2019; 29:188-195. [PMID: 31668616 DOI: 10.1016/j.hlc.2019.08.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 07/01/2019] [Accepted: 08/16/2019] [Indexed: 12/17/2022]
Abstract
Heart failure (HF) is one of the most common causes of death in Western society. Recent results underscore the utility of coenzyme Q10 (CoQ10) addition to standard medications in order to reduce mortality and to improve quality of life and functional capacity in chronic heart failure (CHF). The rationale for CoQ10 supplementation in CHF is two-fold. One is the well-known role of CoQ10 in myocardial bioenergetics, and the second is its antioxidant property. Redox balance is also improved by oral supplementation of CoQ10, and this effect contributes to enhanced endothelium-dependent relaxation. Previous reports have shown that CoQ10 concentration is decreased in myocardial tissue in CHF and by statin therapy, and the greater the CoQ10 deficiency the more severe is the cardiocirculatory impairment. In patients with CHF and hypercholesterolaemia being treated with statins, the combination of CoQ10 with a statin may be useful for two reasons: decreasing skeletal muscle injury and improving myocardial function. Ubiquinol, the active reduced form of CoQ10, presents higher bioavailability than the oxidised form ubiquinone, and should be the preferred form to be added to a statin. The combination ezetimibe/simvastatin may have advantages over single statins. Since ezetimibe reduces absorption of cholesterol and does not affect CoQ10 synthesis in the liver, the impact of this combination on CoQ10 tissue levels will be much less than that of high dose statin monotherapy at any target low density lipoprotein-cholesterol (LDL-C) level to be reached. This consideration makes the ezetimibe/statin combination the ideal LDL-lowering agent to be combined with ubiquinol in CHF patients. However, particular caution is advisable with the use of strategies of extreme lowering of cholesterol that may negatively impact on myocardial function. All in all there is a strong case for considering co-administration of ubiquinol with statin therapy in patients with depressed or borderline myocardial function.
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Affiliation(s)
- Hans-Ulrich Kloer
- Emer, Third Medical Department, UKGM, University of Giessen, Germany
| | | | - Ou Ruchong
- Baker Heart and Diabetes Institute, Melbourne, Vic, Australia; Faculty of Health, Arts and Design, Swinburne University of Technology, Melbourne, Vic, Australia
| | - Franklin Rosenfeldt
- Baker Heart and Diabetes Institute, Melbourne, Vic, Australia; Faculty of Health, Arts and Design, Swinburne University of Technology, Melbourne, Vic, Australia.
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Xia Y, Chen Y, Liu X, Zhou X, Wang Z, Wang G, Xiong Z, Ai L. Enhancement of antroquinonol production during batch fermentation using pH control coupled with an oxygen vector. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2019; 99:449-456. [PMID: 29900550 DOI: 10.1002/jsfa.9206] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 05/20/2018] [Accepted: 06/11/2018] [Indexed: 06/08/2023]
Abstract
BACKGROUND Antroquinonol, a ubiquinone derivative that shows anticancer and anti-inflammatory activities, is produced during solid-state fermentation of Antrodia camphorata; however, it cannot be biosynthesized via conventional submerged fermentation. RESULTS A method for enhancing the biosynthesis of antroquinonol by controlling pH and adding an oxygen vector in a 7 L bioreactor was studied. In shake-flask experiments, a maximum antroquinonol production of 31.39 ± 0.78 mg L-1 was obtained by fermentation with adding 0.2 g L-1 coenzyme Q0 (CoQ0 ), at the 96th hour. Following kinetic analysis of the fermentation process, pH control strategies were investigated. A maximum antroquinonol production of 86.47 ± 3.65 mg L-1 was achieved when the pH was maintained at 5.0, which exhibited an increase of 348.03% higher than the batch without pH regulation (19.30 ± 0.88 mg L-1 ). The conversion rate of CoQ0 improved from 1.51% to 20.20%. Further research revealed that the addition of n-tetradecane could increase the production of antroquinonol to 115.62 ± 4.87 mg L-1 by increasing the dissolved oxygen in the fermentation broth. CONCLUSION The results demonstrated that pH played an important role in antroquinonol synthesis in the presence of the effective precursor CoQ0 . It was a very effective strategy to increase the yield of antroquinonol by controlling pH and adding oxygen vector. © 2018 Society of Chemical Industry.
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Affiliation(s)
- Yongjun Xia
- School of Medical Instrument and Food Engineering, Shanghai Engineering Research Center of Food Microbiology, University of Shanghai for Science and Technology, Shanghai, China
| | - Yan Chen
- School of Medical Instrument and Food Engineering, Shanghai Engineering Research Center of Food Microbiology, University of Shanghai for Science and Technology, Shanghai, China
| | - Xiaofeng Liu
- School of Medical Instrument and Food Engineering, Shanghai Engineering Research Center of Food Microbiology, University of Shanghai for Science and Technology, Shanghai, China
| | - Xuan Zhou
- School of Medical Instrument and Food Engineering, Shanghai Engineering Research Center of Food Microbiology, University of Shanghai for Science and Technology, Shanghai, China
| | - Zhaochu Wang
- School of Medical Instrument and Food Engineering, Shanghai Engineering Research Center of Food Microbiology, University of Shanghai for Science and Technology, Shanghai, China
| | - Guangqiang Wang
- School of Medical Instrument and Food Engineering, Shanghai Engineering Research Center of Food Microbiology, University of Shanghai for Science and Technology, Shanghai, China
| | - Zhiqiang Xiong
- School of Medical Instrument and Food Engineering, Shanghai Engineering Research Center of Food Microbiology, University of Shanghai for Science and Technology, Shanghai, China
| | - Lianzhong Ai
- School of Medical Instrument and Food Engineering, Shanghai Engineering Research Center of Food Microbiology, University of Shanghai for Science and Technology, Shanghai, China
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Petrucci R, Zollo G, Curulli A, Marrosu G. A new insight into the oxidative mechanism of caffeine and related methylxanthines in aprotic medium: May caffeine be really considered as an antioxidant? Biochim Biophys Acta Gen Subj 2018; 1862:1781-1789. [DOI: 10.1016/j.bbagen.2018.05.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 05/09/2018] [Accepted: 05/11/2018] [Indexed: 01/25/2023]
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Smolyaninov IV, Kuzmin VV, Arsenyev MV, Smolyaninova SA, Poddel´sky AI, Berberova NT. Electrochemical transformations and anti/prooxidant activity of sterically hindered o-benzoquinones. Russ Chem Bull 2017. [DOI: 10.1007/s11172-017-1876-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Gulaboski R, Bogeski I, Kokoskarova P, Haeri HH, Mitrev S, Stefova M, Stanoeva JP, Markovski V, Mirčeski V, Hoth M, Kappl R. New insights into the chemistry of Coenzyme Q-0: A voltammetric and spectroscopic study. Bioelectrochemistry 2016; 111:100-8. [DOI: 10.1016/j.bioelechem.2016.05.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Revised: 05/25/2016] [Accepted: 05/26/2016] [Indexed: 12/12/2022]
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9
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Cyclic voltammetry, spectroelectrochemistry and electron spin resonance as combined tools to study thymoquinone in aprotic medium. Electrochim Acta 2012. [DOI: 10.1016/j.electacta.2011.11.055] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Littarru GP, Tiano L, Belardinelli R, Watts GF. Coenzyme Q(10) , endothelial function, and cardiovascular disease. Biofactors 2011; 37:366-73. [PMID: 21674640 DOI: 10.1002/biof.154] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2011] [Accepted: 03/09/2011] [Indexed: 01/15/2023]
Abstract
Since the time a precise role of coenzyme Q(10) (CoQ(10) ) in myocardial bioenergetics was established, the involvement of CoQ in the pathophysiology of heart failure was hypothesized. This provided the rationale for numerous clinical trials of CoQ(10) as adjunctive treatment for heart failure. A mild hypotensive effect of CoQ was reported in the early years of clinical use of this compound. We review early human and animal studies on the vascular effects of CoQ. We then focus on endothelial dysfunction in type 2 diabetes and the possible impact on this condition of antioxidants and nutritional supplements, and in particular the therapeutic effects of CoQ. The effect of CoQ(10) on endothelial dysfunction in ischemic heart disease is also reviewed together with recent data highlighting that treatment with CoQ(10) increases extracellular SOD activity.
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Affiliation(s)
- Gian Paolo Littarru
- Department of Biochemistry, Biology & Genetics, Marche Polytechnic University, Ancona, Italy.
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Kawashima T, Ohkubo K, Fukuzumi S. Stepwise vs. concerted pathways in scandium ion-coupled electron transfer from superoxide ion to p-benzoquinone derivatives. Phys Chem Chem Phys 2011; 13:3344-52. [DOI: 10.1039/c0cp00916d] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Ohtani M, Fukuzumi S. Solubilization and photoinduced electron transfer of single-walled carbon nanotubes wrapped with coenzyme Q10. Chem Commun (Camb) 2009:4997-9. [DOI: 10.1039/b910080f] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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14
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A spectroelectrochemical and chemical study on oxidation of hydroxycinnamic acids in aprotic medium. Electrochim Acta 2007. [DOI: 10.1016/j.electacta.2006.08.053] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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15
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Passi S, Cataudella S, Tiano L, Littarru GP. Dynamics of lipid oxidation and antioxidant depletion in Mediterranean fish stored at different temperatures. Biofactors 2005; 25:241-54. [PMID: 16873953 DOI: 10.1002/biof.5520250130] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Numerous changes occur post-mortem in fish, affecting its chemical composition and nutritional quality. In the present paper we describe the effect of storage on ice or at -30 degrees C or -80 degrees C on 10 species of Mediterranean fish. Water and lipid soluble antioxidants, lipid pattern and products of oxidative attack on lipids, proteins and DNA were quantified for 7 consecutive days on homogenates of fish light muscle. The earliest events were oxidation of ubiquinol and vitamin C, which disappeared almost completely within 48 hours. Ubiquinol oxidation gave rise to an initial increase of ubiquinone, which peaked at the second day: thereafter ubiquinone itslef decreased, more rapidly and to a greater extent than vitamin E. The decrease in antioxidants was accompanied by significant oxidative damage to lipids, proteins and DNA. TBARS significantly increased beginning from the third day of storage in all species and were linked to a significant reduction in the n-3 PUFA of triglycerides (TG) and phospholipid fractions (PL). A remarkable elevation of protein carbonyls and 8OHdG occurred approximately 24 hours later than PUFA oxidation. For SOD, GPX and GSH significant depletions occurred for all species only at 6th or 7th day, but the final values were always higher than 50% compared to the initial ones. Deep-freezing of the same species at -30 degrees C and -80 degrees C for up to 12 months did not significantly affect the levels of enzymatic antioxidants, the redox couple GSH/GS-SG, n-3 and n-6 PUFA of TG and PL fractions of the light muscle. The only antioxidants, which at -30 degrees C and -80 degrees C appeared to be degraded after 6 and 12 months were ubiquinol and vitamin C. As expected their degradation was higher at -30 degrees C than at -80 degrees C. In fact the average decrease for ubiquinol at -80 degrees C was 42% at 6 and 12 months respectively, whereas at -30 degrees C the decrease was 61% and 87% For vitamin C the average decrease at -80 degrees C was 36% and 67% at 6 and 12 months respectively, and at -30 degrees C it was 61% and 82%. Vitamin E was considerably more stable than ubiquinol and vitamin C. The relative stability of the antioxidants, with the exceptions of ubiquionols, vitamin C and, to a certain extent, vitamin E, was accompanied by a very limited increase in oxidation products. In addition no significant hydrolysis of TG and PL fractions were observed throughout the storage time. The dynamics of lipid, protein and DNA oxidation is discussed in the light of depletion of the various antioxidant systems.
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Affiliation(s)
- S Passi
- Centre of Cellular Ageing, IDI-IRCCS, Rome
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16
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Belardinelli R, Muçaj A, Lacalaprice F, Solenghi M, Principi F, Tiano L, Littarru GP. Coenzyme Q10 improves contractility of dysfunctional myocardium in chronic heart failure. Biofactors 2005; 25:137-45. [PMID: 16873938 DOI: 10.1002/biof.5520250115] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND There is evidence that plasma CoQ(10) levels decrease in patients with advanced chronic heart failure (CHF). OBJECTIVE To investigate whether oral CoQ(10) supplementation could improve cardiocirculatory efficiency in patients with CHF. METHODS We studied 21 patients in NYHA class II and III (18M, 3W, mean age 59 +/- 9 years) with stable CHF secondary to ischemic heart disease (ejection fraction 37 +/- 7%), using a double-blind, placebo-controlled cross-over design. Patients were assigned to oral CoQ(10) (100 mg tid) and to placebo for 4 weeks, respectively. RESULTS CoQ(10) supplementation resulted in a threefold increase in plasma CoQ(10) level (P < 0.0001 vs placebo). Systolic wall thickening score index (SWTI) was improved both at rest and peak dobutamine stress echo after CoQ(10) supplementation (+12.1 and 15.6%, respectively, P < 0.05 vs placebo). Left ventricular ejection fraction improved significantly also at peak dobutamine (15% from study entry P < 0.0001) in relation to a decrease in LV end-systolic volume index (from 57 +/- 7 mL/m(2) to 45 mL/m(2), P < 0.001). Improvement in the contractile response was more evident among initially akinetic (+33%) and hypokinetic (+25%) segments than dyskinetic ones (+6%). Improvement in SWTI was correlated with changes in plasma CoQ(10) levels (r = -0.52, P < 0.005). Peak VO(2) was also improved after CoQ(10) as compared with placebo (+13%, <0.005). No side effects were reported with CoQ(10). CONCLUSIONS Oral CoQ(10) improves LV contractility in CHF without any side effects. This improvement is associated with an enhanced functional capacity.
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Affiliation(s)
- Romualdo Belardinelli
- Lancisi Heart Institute, Department of Cardiology and Cardiac Surgery, Ancona, Italy.
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Hodgson JM, Watts GF. Can coenzyme Q10 improve vascular function and blood pressure? Potential for effective therapeutic reduction in vascular oxidative stress. Biofactors 2003; 18:129-36. [PMID: 14695928 DOI: 10.1002/biof.5520180215] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Coenzyme Q10 (CoQ) is an endogenously synthesised compound that acts as an electron carrier in the mitochondrial electron transport chain. The presence of adequate tissue concentrations of CoQ may be important in limiting oxidative and nitrosative damage in vivo. Oxidative and nitrosative stress are likely to be elevated in conditions such as diabetes and hypertension. In these conditions elevated oxidative and nitrosative stress within the arterial wall may contribute to increased blood pressure and vascular dysfunction. The major focus of this review is the potential of CoQ to improve vascular function and lower blood pressure. Although there is substantial indirect support for the putative mechanism of effect of CoQ on the vascular system, to date there is little direct support for an effect of CoQ on in vivo markers of oxidative or nitrosative stress. The limited data available from studies in animal models and from human intervention studies are generally consistent with a benefit of CoQ on vascular function and blood pressure. The observed effects of CoQ on these endpoints are potentially important therapeutically. However, before any firm clinical recommendations can be made about CoQ supplementation, further intervention studies in humans are needed to investigate the effects of CoQ on vascular function, blood pressure and cardiovascular outcomes. The particularly relevant groups of patients for these studies are those with insulin resistance, type 2 diabetes, hypertension and the metabolic syndrome.
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Affiliation(s)
- Jonathan M Hodgson
- University of Western Australia School of Medicine and Pharmacology and the Western Australian Institute for Medical Research, Royal Perth Hospital, Western Australia, Australia
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Giorgini E, Tommasi G, Stipa P, Tosi G, Littarru G, Greci L. Reactivity of ubiquinones and ubiquinols with free radicals. Free Radic Res 2001; 35:63-72. [PMID: 11697118 DOI: 10.1080/10715760100300601] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The reactivity of quinones 1-4 and of the corresponding quinols 5-8 towards carbon- and oxygen-centred radicals were studied. All quinones bearing at least one nuclear position free, readily react with alkyl and phenyl radicals to afford the alkylated quinones 12-24; however, quinones 1 and 3 reacted with 2-cyano-2-propyl radical to yield products (the mono- and di-ethers 9-11) derived from the attack on the carbonylic oxygen. The reactions carried out on quinones with the benzoyloxy radical led to no reaction products and in the case of Q10, the isoprenic chain also remained unchanged. Quinols 5-8 reacted only with oxygen-centred radicals (benzoyloxy and 2-cyano-2-propyl-peroxy radicals) to give the corresponding quinones. The isoprenic chain of Q10 did not undergo attack even with peroxy radicals. Carbon-centred radicals resulted unable to abstract hydrogen from the studied quinols.
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Affiliation(s)
- E Giorgini
- Dipartimento di Scienze dei Materiali e della Terra, via Brecce Bianche, Università, I-60131 Ancona, Italy
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Abstract
The coenzyme function of ubiquinone was subject of extensive studies in mitochondria since more than 40 years. The catalytic activity of ubiquinone (UQ) in electron transfer and proton translocation in cooperation with mitochondrial dehydrogenases and cytochromes contributes essentially to the bioenergetic activity of ATP synthesis. In the past two decades UQ was recognized to exert activities which differ from coenzyme functions in mitochondria. From extraction/reincorporation experiments B. Chance has drawn the conclusion that redox-cycling of mitochondrial ubiquinone supplies electrons for univalent reduction of dioxygen. The likelihood of O2(.-) release as normal byproduct of respiration was based on the existence of mitochondrial SOD and the fact that mitochondrial oxygen turnover accounts for more than 90% of total cellular oxygen consumption. Arguments disproving this concept are based on results obtained from a novel noninvasive, more sensitive detection method of activated oxygen species and novel experimental approaches, which threw light into the underlying mechanism of UQ-mediated oxygen activation. Single electrons for O2(.-) formation are exclusively provided by deprotonated ubisemiquinones. Impediment of redox-interaction with the bc1 complex in mitochondria or the lack of stabilizing interactions with redox-partners are promotors of autoxidation. The latter accounts for autoxidation of antioxidant-derived ubisemiquinones in biomembranes, which do not recycle oxidized ubiquinols. Also O2(.-)-derived H2O2 was found to interact with ubisemiquinones both in mitochondria and nonrecycling biomembranes when ubiquinol was active as antioxidant. The catalysis of reductive homolytic cleavage of H2O2, which contributes to HO. formation in biological systems was confirmed under defined chemical conditions in a homogenous reduction system. Apart from dioxygen and hydrogen peroxide we will provide evidence that also nitrite may chemically interact with the ubiquinol/bc1 redox couple in mitochondria. The reaction product NO was reported elsewhere to be a significant bioregulator of the mitochondrial respiration and O2 activation. Another novel finding documents the bioenergetic role of UQ in lysosomal proton intransport. A lysosomal chain of redox couples will be presented, which includes UQ and which requires oxygen as the terminal electron acceptor.
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Affiliation(s)
- H Nohl
- Institute of Pharmacology and Toxicology, Veterinary University of Vienna, Veterinärplatz 1, Vienna, A-1210, Austria
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