COVID-19 and the Assessment of Coenzyme Q10.

Coenzyme Q10 (CoQ10) plays an essential electron carrier role in the mitochondrial electron transfer chain (ETC) as well as being a potent antioxidant and influencing inflammatory mediators. In view of these functions, the reason why certain individuals may be more susceptible to the severe disease or long-term complications (long COVID) of COVID-19 infection may be associated with an underlying deficit in cellular CoQ10 status. Thus, our group has outlined an analytical method for the determination of cellular CoQ10 status using HPLC linked UV detection at 275 nm. This method has been utilized in patient tissue samples to investigate evidence of a CoQ10 deficiency and thus may have potential in determining the possible susceptibility of individuals to severe disease associated with COVID-19 infection or to long COVID.

Coenzyme Q10 Assessment and the Establishment of a Neuronal Cell Model of CoQ10 Deficiency.

Coenzyme Q10 (CoQ10) plays a key role as an electron carrier in the mitochondrial respiratory chain and as a cellular antioxidant molecule. A deficit in CoQ10 status may contribute to disease pathophysiology by causing a failure mitochondrial energy metabolism as well as compromising cellular antioxidant capacity. This chapter outlines the analytical methods used for determining cellular CoQ10 status using high-pressure liquid chromatography with ultraviolet (HPLC-UV) detection. In addition, we present a pharmacological procedure for establishing a human neuronal cell model of CoQ10 deficiency, for use in research studies.

Importance of the assessment of coenzyme Q10, alpha-tocopherol and oxidative stress for the diagnosis and therapy of infertility in men.

UNLABELLED: Male infertility is one of the most stressful factors of couples, being present in about 40% cases. It is usually caused by a low number of sperm (oligozoospermia) or poor sperm motility (asthenozoospermia). The sperm motility is used as an indicator of semen quality and male infertility. To the impairment of male reproduction health can contribute genetic, nutritional and environmental factors, smoking and drugs. It is well documented that excessive reactive oxygen species (ROS) production decreases sperm motility, impairs sperm function, damages the morphology of spermatozoa (1, 2). To the decreased sperm motility contribute also disturbances of sperm mitochondrial function and energy production, low levels of coenzyme Q10 and carnitine, as well as sperm mitochondrial deoxyribonucleic acid (DNA) defects. The origin of sperm dysfunction, however, is not well understood. BACKGROUND: Oxidative stress has been established as a major factor in the pathogenesis of male infertility. Low level of coenzyme Q10 contributes to the decreased sperm motility, which plays a vital role in sperm mitochondrial energy production and neutralization of reactive oxygen species (ROS).The aim of the present study was to find out, if an assessment of coenzyme Q10-TOTAL (CoQ10-TOTAL), α-tocopherol, γ-tocopherol and oxidative stress could contribute to the diagnosis of infertility in men. SUBJECTS AND METHODS: Two groups of infertile men, according to sperm motility (a+b and b+c) were included in the study. CoQ10-TOTAL, α-tocopherol, γ-tocopherol in plasma and seminal fluid, and parameter of oxidative stress (thiobarbituric acid reactive substances - TBARS) in plasma were determined. RESULTS: Higher sperm density and decreased sperm pathology were found in group a+b vs b+c (class a and b - fast and weak forward motility, class c - nonprogressive motility). Concentrations of CoQ10-TOTAL and α-tocopherol were significantly increased in seminal fluid of groups a+b vs b+c, opposite results were estimated in plasma. Concentrations of γ-tocopherol in plasma and seminal fluid of both groups were similar. Plasmatic TBARS concentrations were increased in both groups of infertile men. CONCLUSION: We suppose that incorporation of oxidative stress assessment, CoQ10-TOTAL and α-tocopherol concentrations in seminal fluid and plasma into routine andrology can play an important role for the diagnosis and targeted therapy of male infertility (Tab. 1, Ref. 16).

Redox-linked protonation state changes in cytochrome bc1 identified by Poisson-Boltzmann electrostatics calculations.

Cytochrome bc(1) is a major component of biological energy conversion that exploits an energetically favourable redox reaction to generate a transmembrane proton gradient. Since the mechanistic details of the coupling of redox and protonation reactions in the active sites are largely unresolved, we have identified residues that undergo redox-linked protonation state changes. Structure-based Poisson-Boltzmann/Monte Carlo titration calculations have been performed for completely reduced and completely oxidised cytochrome bc(1). Different crystallographically observed conformations of Glu272 and surrounding residues of the cytochrome b subunit in cytochrome bc(1) from Saccharomyces cerevisiae have been considered in the calculations. Coenzyme Q (CoQ) has been modelled into the CoQ oxidation site (Q(o)-site). Our results indicate that both conformational and protonation state changes of Glu272 of cytochrome b may contribute to the postulated gating of CoQ oxidation. The Rieske iron-sulphur cluster could be shown to undergo redox-linked protonation state changes of its histidine ligands in the structural context of the CoQ-bound Q(o)-site. The proton acceptor role of the CoQ ligands in the CoQ reduction site (Q(i)-site) is supported by our results. A modified path for proton uptake towards the Q(i)-site features a cluster of conserved lysine residues in the cytochrome b (Lys228) and cytochrome c(1) subunits (Lys288, Lys289, Lys296). The cardiolipin molecule bound close to the Q(i)-site stabilises protons in this cluster of lysine residues.

Assessment of coenzyme Q10 absorption using an in vitro digestion-Caco-2 cell model.

The feasibility of using a coupled in vitro digestion-Caco-2 cell uptake as a model for examining the digestive stability and absorption of coenzyme Q10 (CoQ10) from a variety of commercially available CoQ10 products was examined. The products were first subjected to simulated digestion to mimic their passage through the GI tract to generate micelles containing CoQ10, and the micelle fractions added to monolayers of Caco-2 cells to determine CoQ10 uptake. The data demonstrate enhanced uptake of CoQ10 from formulations containing solubilized forms of CoQ10 and also from a CoQ10-gamma-cyclodextrin complex as compared with pure CoQ10 powder or tablets based on CoQ10 powder. The CoQ10 uptake by the cells was correlated with the extent of micellarization of CoQ10 during simulated digestion. Most of CoQ10 taken up by the cells was converted to ubiquinol either during or following uptake. The data also indicate a correlation between in vitro dissolution of CoQ10 products and uptake of CoQ10 by Caco-2 cells. Thus, this study demonstrates the utility of coupled in vitro digestion-Caco-2 cell model as a cost-effective screening tool that will provide useful information for the optimal design of human trials to assess the bioavailability of CoQ10 and also other bioactive compounds.

An improved method for analyzing coenzyme Q homologues and multiple detection of rare biological samples.

We have developed a simple method for the estimation of coenzyme Q homologues, neurotransmitters, metal ions, lipid peroxidation, gene expression, and DNA fragmentation simultaneously from genetically engineered mice brain regions and cultured neurons. The primary objective of this study was to improve conventional time-consuming, cumbersome, and less efficient procedures, and reduce the cost of conducting kinetic studies in rare biological samples. The improved method is novel, precise, efficient, accurate, sensitive, economical, versatile, and highly reproducible. The recovery and shelf life of coenzyme Q homologues was significantly increased and the chromatograms exhibited reduced background and retention times. It is envisaged that in addition to coenzyme Q homologues, the improved method could be utilized for the multiple analyses of DNA, RNA and proteins from clinically significant biopsy and autopsy samples.

A modular NIRS system for clinical measurement of impaired skeletal muscle oxygenation.

Near-infrared spectrometry (NIRS) is a well-known method used to measure in vivo tissue oxygenation and hemodynamics. This method is used to derive relative measures of hemoglobin (Hb) + myoglobin (Mb) oxygenation and total Hb (tHb) accumulation from measurements of optical attenuation at discrete wavelengths. We present the design and validation of a new NIRS oxygenation analyzer for the measurement of muscle oxygenation kinetics. This design optimizes optical sensitivity and detector wavelength flexibility while minimizing component and construction costs. Using in vitro validations, we demonstrate 1) general optical linearity, 2) system stability, and 3) measurement accuracy for isolated Hb. Using in vivo validations, we demonstrate 1) expected oxygenation changes during ischemia and reactive hyperemia, 2) expected oxygenation changes during muscle exercise, 3) a close correlation between changes in oxyhemoglobin and oxymyoglobin and changes in deoxyhemoglobin and deoxymyoglobin and limb volume by venous occlusion plethysmography, and 4) a minimal contribution from movement artifact on the detected signals. We also demonstrate the ability of this system to detect abnormal patterns of tissue oxygenation in a well-characterized patient with a deficiency of skeletal muscle coenzyme Q(10). We conclude that this is a valid system design for the precise, accurate, and sensitive detection of changes in bulk skeletal muscle oxygenation, can be constructed economically, and can be used diagnostically in patients with disorders of skeletal muscle energy metabolism.

The random collision model and a critical assessment of diffusion and collision in mitochondrial electron transport.

This review focuses on our studies over the past ten years which reveal that the mitochondrial inner membrane is a fluid-state rather than a solid-state membrane and that all membrane proteins and redox components which catalyze electron transport and ATP synthesis are in constant and independent diffusional motion. The studies reviewed represent the experimental basis for the random collision model of electron transport. We present five fundamental postulates upon which the random collision model of mitochondrial electron transport is founded: All redox components are independent lateral diffusants; Cytochrome c diffuses primarily in three dimensions; Electron transport is a diffusion-coupled kinetic process; Electron transport is a multicollisional, obstructed, long-range diffusional process; The rates of diffusion of the redox components have a direct influence on the overall kinetic process of electron transport and can be rate limiting, as in diffusion control. The experimental rationales and the results obtained in testing each of the five postulates of the random collision model are presented. In addition, we offer the basic concepts, criteria and experimental strategies that we believe are essential in considering the significance of the relationship between diffusion and electron transport. Finally, we critically explore and assess other contemporary studies on the diffusion of inner membrane components related to electron transport including studies on: rotational diffusion, immobile fractions, complex formation, dynamic aggregates, and rates of diffusion. Review of all available data confirms the random collision model and no data appear to exist that contravene it. It is concluded that mitochondrial electron transport is a diffusion-based random collision process and that diffusion has an integral and controlling affect on electron transport.