Urinary coenzyme Q10 as a diagnostic biomarker and predictor of remission in a patient with ADCK4-associated Glomerulopathy: a case report.

BACKGROUND: AarF domain-containing kinase 4 (ADCK4)-associated glomerulopathy is a mitochondrial nephropathy caused by mutations in the ADCK4 gene, which disrupt coenzyme Q10 biosynthesis. CASE PRESENTATION: We report the case of a 25-year-old female patient with ADCK4-associated glomerulopathy presenting with proteinuria (and with no additional systemic symptoms). A known missense substitution c.737G > A (p.S246N) and a novel frameshift c.577-600del (p.193-200del) mutation were found. We followed the patient for 24 months during supplementation with coenzyme Q10 (20 mg/kg/d - 30 mg/kg/d) and describe the clinical course. In addition, we measured serum and urine coenzyme Q10 levels before and after coenzyme Q10 supplementation and compared them with those of healthy control subjects. The patient's urinary coenzyme Q10 to creatinine ratio was higher than that of healthy controls before coenzyme Q10 supplementation, but decreased consistently with proteinuria after coenzyme Q10 supplementation. CONCLUSIONS: Although the use of urinary coenzyme Q10 as a diagnostic biomarker and predictor of clinical remission in patients with ADCK4-associated glomerulopathy should be confirmed by larger studies, we recommend measuring urinary coenzyme Q10 in patients with isolated proteinuria of unknown cause, since it may provide a diagnostic clue to mitochondrial nephropathy.

A rapid and non-invasive fluorescence method for quantifying coenzyme Q10 in blood and urine in clinical analysis.

BACKGROUND: Coenzyme Q10 (CoQ10) supplementation can improve cognition in patients with Alzheimer's disease (AD) and AD transgenic model mice. To ameliorate the discomfort that patients with AD suffer after several blood extractions, a non-invasive method for detecting urine CoQ10 levels needs to be established. METHODS: Here, we developed a new technique of fluorescence spectrophotometry with ethyl cyanoacetate (FS-ECA), on the basis of the principle that the chemical derivative obtained from the interaction between CoQ10 and ECA was detected by a fluorescence detector at λex/em  = 450/515 nm. As a standard reference method, the same batches of the clinical samples were analyzed by high-performance liquid chromatography with an ultraviolet detector (HPLC-UV) at 275 nm. RESULTS: The limits of detection (LOD) and limits of quantization (LOQ) (serum: 0.021 and 0.043 mg/L; urine: 0.012 and 0.025 mg/L) determined by the FS-ECA method were similar to that obtained through HPLC-UV (serum: 0.017 and 0.035 mg/L; urine: 0.012 and 0.025 mg/L). More importantly, this new FS-ECA technique as well as the conventional HPLC-UV method could detect a marked difference in urine CoQ10 levels between AD and controls. CONCLUSION: Our findings suggest that this non-invasive method for quantifying urine CoQ10 potentially replaces HPLC to detect blood CoQ10.

Miniaturized imprinted solid phase extraction to the selective analysis of Coenzyme Q10 in urine.

Coenzyme Q10 (CoQ10) is an important cofactor in the mitochondrial respiratory chain and a potent endogenous antioxidant. CoQ10 deficiency is currently associated with numerous diseases like mitochondrial and neurodegenerative pathologies, in which the earliest diagnosis and treatment with CoQ10 supplementation becomes paramount for patient's treatment. Consequently, the determination of CoQ10 levels in different biological matrices positions as a fundamental tool. Urine is an attractive and non-invasive alternative source to tissue, blood or other biofluids for CoQ10 analysis. However, it poses an analytical challenge, as it generally requires a complex sample preparation, with multiple steps. In this work we developed and validated a molecularly imprinted polymer solid phase extraction (MIP-SPE) followed by a HPLC-MS/MS method for the analysis of CoQ10 in urine. The MIP-SPE method developed is simple and fast compared to previously traditional reported methods, with reduced processing time, improved sample cleaning and excellent recovery values, along with its inherent high selectivity. The developed chromatographic method was validated according to FDA guidelines, and demonstrated to be suitable for the analysis of CoQ10 in urine samples with LOQ and LOD values of 0.6 ng/mL and 0.2 ng/mL of CoQ10 in urine respectively. Recovery values at three concentration levels were higher than 90.0%.The proposed method is amenable to be applied in pediatric patients due to the low sample requirement and useful for diagnosis and post-treatment control.

Determination of urinary coenzyme Q10 by HPLC with electrochemical detection: Reference values for a paediatric population.

Kidney dysfunction is being increasingly associated with mitochondrial diseases and coenzyme Q10 (CoQ) deficiency. The assessment of CoQ status requires the biochemical determination of CoQ in biological fluids and different cell types, but no methods have been developed as yet for the analysis of CoQ in excretory systems. The aim of this study was to standardize a new procedure for urinary CoQ determination and to establish reference values for a paediatric population. Urinary CoQ was analyzed by HPLC with electrochemical detection. Reference values (n = 43) were stratified into two age groups (2-10 years: range 24-109 nmol CoQ/gram of pellet protein; 11-17 years: range 43-139 nmol CoQ/gram of pellet protein). In conclusion, urinary CoQ analysis is a noninvasive, reliable, and reproducible method to determine urinary tract CoQ status.

Metabolites of antroquinonol found in rat urine following oral administration.

Four metabolites (1-4) of antroquinonol from rat urine, collected within 24 h after oral administration of antroquinonol, were characterized by HPLC-SPE-NMR. Compounds 1-4 were further isolated by semipreparative HPLC for structure confirmation. Their structures were elucidated on the basis of 1D and 2D NMR spectroscopic analyses and HRESIMS data.

Urinary excretion study of coenzyme Q10 in rats by ultra-performance liquid chromatography-mass spectrometry.

A method based on ultra-performance liquid chromatography mass spectrometry (UPLC-MS) applying atmospheric pressure chemical ionization in the positive ion mode is developed for the determination of coenzyme Q10 (CoQ10) in rat urine. The assay involves the extraction of crude urine, fast liquid chromatography on a Waters Acquity UPLC BEH C18 column (1.7 microm, 1.0 x 50 mm), and selected ion monitoring detection using mass transition. The calibration range is found to be 0.05-25 microg/mL, with the lower limit of quantitation of 0.05 microg/mL. Intra- and inter-day precision (relative standard deviation) for CoQ10 in rat urine range from 0.7% to 15%, and accuracy expressed in recovery rates in urine is between 83% and 118%. The recovery of this method is found to be between 80% and 95% at three concentrations. The total cumulative recovery of CoQ10 is 1.16 +/- 1.05% (percentage of dose intake, n = 4) from rat urine collected over 30 h after oral administration of the drug. The UPLC-MS method described allows the quick determination of CoQ10 in rat urine with good precision and accuracy. It is suitable for further excretion studies of CoQ10 in animals.

Increased nonsterol isoprenoids, dolichol and ubiquinone, in the Smith-Lemli-Opitz syndrome: effects of dietary cholesterol.

Smith-Lemli-Opitz syndrome (SLOS) is an inherited autosomal recessive cholesterol deficiency disorder. Our studies have shown that in SLOS children, urinary mevalonate excretion is normal and reflects hepatic HMG-CoA reductase activity but not ultimate sterol synthesis. Hence, we hypothesized that in SLOS there may be increased diversion of mevalonate to nonsterol isoprenoid synthesis. To test our hypothesis, we measured urinary dolichol and ubiquinone, two nonsterol isoprenoids, in 16 children with SLOS and 15 controls, all fed a low-cholesterol diet. The urinary excretion of both dolichol (P < 0.002) and ubiquinone (P < 0.02) in SLOS children was 7-fold higher than in control children, whereas mevalonate excretion was comparable. In a subset of 12 SLOS children, a high-cholesterol diet decreased urinary mevalonate excretion by 61% (P < 0.001), dolichol by 70% (P < 0.001), and ubiquinone by 67% (P < 0.03). Our hypothesis that in SLOS children, normal urinary mevalonate excretion results from increased diversion of mevalonate into the production of nonsterol isoprenoids is supported. Dietary cholesterol supplementation reduced urinary mevalonate and nonsterol isoprenoid excretion but did not change the relative ratios of their excretion. Therefore, in SLOS, a secondary peripheral regulation of isoprenoid synthesis may be stimulated.

Metabolism of coenzyme Q10: biliary and urinary excretion study in guinea pigs.

Biliary and urinary metabolites were examined after intravenous administration of 14C-coenzyme Q10 (14C-CoQ) to guinea pigs. Cumulative recovery of administered radioactivity for up to 8 hours by bile drainage was 4.8%. The greater part of radioactivity was detected in conjugate form. After hydrolyzing with beta-glucuronidase, aglycone fragments were subjected to methylation and reductive acetylation. The main metabolite was demonstrated to be Q acid-1 1,4-hydroquinone diacetate methyl ester (M-1) on HPLC. Then, the main metabolite was assumed to be glucuronide of 2,3-dimethoxy-5-methyl-6-(3'-methyl-5'-carboxy-2'-pentenyl)-1, 4-benzohydroquinone [Q acid-I hydroquinone]. The cumulative urinary recovery of the administered radioactivity over 48 hours was 8.3%. The labeled samples were treated similarly to bile. The urinary metabolites of CoQ10 consisted of unconjugated and conjugated forms. Lyophilized urine was treated as a bile sample and analyzed. The two major metabolites were assigned to be M-1 and Q acid-II 1,4-hydroquinone diacetate methyl ester (M-2). Then, the two metabolites were assumed to be composed of Q acid-I and 2,3-dimethoxy-5-methyl-6-(3'-carboxypropyl)-1,4-benzoquinone (Q acid-II) in free and corresponding hydroquinone conjugate forms. To investigate the effect of exogenous labeled CoQ10 on unlabeled CoQ10 (endogenous) metabolites in urine, simultaneous quantitative determination was performed using deuterium labeled CoQ10 (CoQ10-d5). Urine collected over a 72-hour period after intravenous administration of CoQ10-d5 was processed similarly to that described above and two derivatized metabolites (M-1 and M-2) were quantified by gas chromatography-mass fragmentography with the multi-ion detection method. The analytical results showed that the addition of exogenous labeled CoQ10 did not influence the metabolism (or breakdown) of unlabeled (endogenous) CoQ10.

Human serum ubiquinol-10 levels and relationship to serum lipids.

Serum and urinary levels of ubiquinol-10 (UQH2-10) as well as total ubiquinone-10 (total UQ-10, sum of UQH2-10 and oxidized UQ-10) were determined in healthy Japanese subjects using high performance liquid chromatography with an electrochemical detector. The mean serum and urinary levels of UQH2-10 were 0.75 +/- 0.21 microgram/ml (86% of total UQ-10, n = 77) and 0.045 +/- 0.016 microgram/mg creatinine (59% of total UQ-10, n = 30), respectively. After daily oral administration of 60 mg of UQ-10 for 7 days, the human serum level of UQH2-10 increased twice as compared to that before the treatment. However, the ratio of the UQH2-10 to the total UQ-10 remained unchanged during such administration. The serum level of UQH2-10 correlated significantly with those of vitamin E (p less than 0.001), phospholipids (p less than 0.01), total cholesterol (p less than 0.05), and total lipids (p less than 0.05). There was no correlationship between the serum levels of UQH2-10 and of triglycerides and lipid peroxides.

Determination of reduced and total ubiquinones in biological materials by liquid chromatography with electrochemical detection.

A convenient and reliable liquid chromatographic (LC) method with electrochemical detection (ED) was developed for the determination of reduced (ubiquinol) and total ubiquinones in biological materials. After extraction of samples with n-hexane, ubiquinol was separated on a reversed-phase column and assayed directly by ED. In order to determine the total amount of a ubiquinone in biological samples, the unbiquinone was converted into the corresponding reduced form by treatment with sodium borohydride. No significant interfering peak (plastoquinol-9, ubichromenol-9, etc.) was observed in the elution areas of ubiquinol-7 to -11. This LC-ED method was about 70 times more sensitive than the previous LC-UV method and was able to detect 150 pg of ubiquinol-10. The method was applied satisfactorily to the determination of the contents of ubiquinol homologues in biological materials. The content of ubiquinols is a major component of the total ubiquinones in human plasma and urine and rat plasma and liver, but a minor component in rat heart and kidney.

High-performance liquid chromatography of coenzyme Q-related compounds and its application to biological materials.

A convenient and precise method for the separation and determination of coenzyme Q (CoQ)-related compounds (CoQ homologues, plastoquinone-9, ubichromenol-9, etc.) was developed using high-performance liquid chromatography (HPLC). All compounds tested were separated using a reverse-phase column with a suitable mobile phase and detected at a wavelength of 275 nm. CoQ extracts in plasma and erythrocytes were purified by thin-layer chromatography prior to HPLC analysis, but such purification was not necessary when determining CoQ in urine and tissues. Hydroquinone forms of CoQ existing in animal tissues were oxidized to the corresponding quinone forms with potassium hexacyanoferrate(III). This HPLC method was applied satisfactorily to the determination of the contents of CoQ homologues in human and animal samples. CoQ10 was the only homologue detected in human samples, and CoQ8, CoQ9 and CoQ10 were native homologues of CoQ in rat tissues. Ubichromenol-9 and plastoquinone-9 were not detected in these samples.