The emerging role of coenzyme Q-10 in aging, neurodegeneration, cardiovascular disease, cancer and diabetes mellitus.
Coenzyme Q (ubiquinone, 2-methyl-5,6-dimethoxy-1,4-benzoquinone), soluble natural fat quinine, is crucial to optimal biological function. The coenzyme Q molecule has amphipathic (biphasic) properties due to the hydrophilic benzoquinone ring and the lipophilic poly isoprenoid side-chain. The nomenclature of coenzyme Q-n is based on the amount of isoprenoid units attached to 6-position on the benzoquinone ring. It was demonstrated that coenzyme Q, in addition to its role in electron transport and proton transfer in mitochondrial and bacterial respiration, acts in its reduced form (ubiquinol) as an antioxidant. Coenzyme Q-10 functions as a lipid antioxidant regulating membrane fluidity, recycling radical forms of vitamin C and E, and protecting membrane phospholipids against peroxidation. The antioxidant property, high degree of hydrophobicity and universal occurrence in biological system, suggest an important role for ubiquinone and ubiquinol in cellular defense against oxidative damage. Coenzyme Q-10 is a ubiquitous and endogenous lipid-soluble antioxidant found in all organisms. Neurodegenerative disorders, cancer, cardiovascular diseases and diabetes mellitus and especially aging and Alzheimer’s disease exhibit altered levels of ubiquinone or ubiquinol, indicating their likely crucial role in the pathogenesis and cellular mechanisms of these ailments. This review is geared to discuss the biological effect of coenzyme Q with an emphasis on its impact in initiation, progression, treatment and prevention of neurodegenerative, cardiovascular and carcinogenic diseases.
Curr Neurovasc Res. 2005 Dec;2(5):447-59
Improvement of visual functions and fundus alterations in early age-related macular degeneration treated with a combination of acetyl-L-carnitine, n-3 fatty acids, and coenzyme Q10.
The aim of this randomized, double-blind, placebo-controlled clinical trial was to determine the efficacy of a combination of acetyl-L-carnitine, n-3 fatty acids, and coenzyme Q10 (Phototrop) on the visual functions and fundus alterations in early age-related macular degeneration (AMD). One hundred and six patients with a clinical diagnosis of early AMD were randomized to the treated or control groups. The primary efficacy variable was the change in the visual field mean defect (VFMD) from baseline to 12 months of treatment, with secondary efficacy parameters: visual acuity (Snellen chart and ETDRS chart), foveal sensitivity as measured by perimetry, and fundus alterations as evaluated according to the criteria of the International Classification and Grading System for AMD. The mean change in all four parameters of visual functions showed significant improvement in the treated group by the end of the study period. In addition, in the treated group only 1 out of 48 cases (2%) while in the placebo group 9 out of 53 (17%) showed clinically significant (>2.0 dB) worsening in VFMD (p = 0.006, odds ratio: 10.93). Decrease in drusen-covered area of treated eyes was also statistically significant as compared to placebo when either the most affected eyes (p = 0.045) or the less affected eyes (p = 0.017) were considered. These findings strongly suggested that an appropriate combination of compounds which affect mitochondrial lipid metabolism, may improve and subsequently stabilize visual functions, and it may also improve fundus alterations in patients affected by early AMD.
Ophthalmologica. 2005 May-Jun;219(3):154-66
Low plasma coenzyme Q10 levels as an independent prognostic factor for melanoma progression.
BACKGROUND: Abnormally low plasma levels of coenzyme Q10 (CoQ10) have been found in patients with cancer of the breast, lung, or pancreas. OBJECTIVE: A prospective study of patients with melanoma was conducted to assess the usefulness of CoQ10 plasma levels in predicting the risk of metastasis and the duration of the metastasis-free interval. METHODS: Between January 1997 and August 2004, plasma CoQ10 levels were measured with high-performance liquid chromatography in 117 consecutive melanoma patients without clinical or instrumental evidence of metastasis according to American Joint Committee on Cancer criteria and in 125 matched volunteers without clinically suspect pigmented lesions. Patients taking CoQ10 or cholesterol-lowering medications and those with a diagnosis of diabetes mellitus were excluded from the study. Multiple statistical methods were used to evaluate differences between patients and control subjects and between patients who did (32.5%) and did not (67.5%) develop metastases during follow-up. RESULTS: CoQ10 levels were significantly lower in patients than in control subjects (t test: P < .0001) and in patients who developed metastases than in the metastasis-free subgroup (t test: P < .0001). Logistic regression analysis indicated that plasma CoQ10 levels were a significant predictor of metastasis (P = .0013). The odds ratio for metastatic disease in patients with CoQ10 levels that were less than 0.6 mg/L (the low-end value of the range measured in a normal population) was 7.9, and the metastasis-free interval was almost double in patients with CoQ10 levels 0.6 mg/L or higher (Kaplan-Meier analysis: P < .001). LIMITATIONS: A study with a larger sample, which is currently being recruited, and a longer follow-up will doubtlessly increase the statistical power and enable survival statistics to be obtained. CONCLUSIONS: Analysis of our findings suggests that baseline plasma CoQ10 levels are a powerful and independent prognostic factor that can be used to estimate the risk for melanoma progression.
J Am Acad Dermatol. 2006 Feb;54(2):234-41
An increase of oxidized coenzyme Q-10 occurs in the plasma of sporadic ALS patients.
We have compared plasma redox status of coenzyme Q-10 in 20 sporadic amyotrophic lateral sclerosis (sALS) patients with those in 20 healthy age/sex-matched controls. A significant increase in the oxidized form of coenzyme Q-10 (sALS=109.3+/-95.2 nM; controls=23.3+/-7.5 nM, P=0.0002) and in the ratio of oxidized form of coenzyme Q-10 to total coenzyme Q-10 (%CoQ-10) (sALS=12.0+/-9.3%; controls=3.2+/-0.9%, P<0.0001) were observed. Moreover, %CoQ-10 correlated significantly with the duration of illness (rho=0.494, P=0.0315). Our finding suggests systemic oxidative stress in the pathogenesis of sALS.
J Neurol Sci. 2005 Jan 15;228(1):49-53
Tolerance of high-dose (3,000 mg/day) coenzyme Q10 in ALS.
An open-label dose-escalation trial was performed to assess the safety and tolerability of high doses of coenzyme Q10 (CoQ10) in ALS. CoQ10, a cofactor in mitochondrial electron transfer, may improve the mitochondrial dysfunction in ALS. In this study, CoQ10 was safe and well tolerated in 31 subjects treated with doses as high as 3,000 mg/day for 8 months.
Neurology. 2005 Dec 13;65(11):1834-6
Muscle biopsy in Alzheimer’s disease: morphological and biochemical findings.
Recent evidences of a predisposing genetic factor associated with Alzheimer’s disease (DAT) suggests that important alterations may be expressed in tissues other than the brain. We present morphological and biochemical studies on muscle obtained from ten patients with Alzheimer’s disease and coeval controls. Muscle biopsy examination showed an increased subsarcolemmal mitochondrial oxidative activity in three patients. The biochemical studies showed an increased oxidative enzyme activity only in the DAT group. The CoQ10 level, studied so far in three DAT patients, was greatly reduced (approximately 50%) compared with controls. Possible new peripheral markers in Alzheimer’s disease will be discussed.
Clin Neuropathol. 1991 Jul-Aug;10(4):171-6.