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

Spectrofluorophotometric Analysis of Phytoconstituents, Biomarkers, Enzyme Kinetics and Trace Metals: A Comprehensive Review

Spectrofluorophotometry is a highly sensitive and selective analytical technique widely employed in pharmaceutical, biomedical, and environmental sciences. This review provides a comprehensive application for detecting and quantifying phytoconstituents, biomarkers, enzyme kinetics, and trace metals. This technique offers detection of analyte in the femtomolar (fM) range. Phytochemicals such as flavonoids, alkaloids, and polyphenols were analyzed with high precision and accuracy, and the reported analytical method can be adopted for quality control analysis. Spectrofluorophotometry has been utilized to estimate biomarkers, which plays a critical role in disease diagnostics and therapeutic monitoring. It also facilitates the monitoring of enzyme kinetics, offering insights into metabolic processes and drug development. Additionally, its ability to detect trace metals through chelation and fluorescence quenching mechanisms proves vital for environmental and toxicological analysis. Despite challenges such as fluorescence quenching and environmental susceptibility, advancements in miniaturization, automation, and hybrid analytical techniques continue to enhance their capabilities. This review underscores the transformative impact of spectrofluorophotometry and its expanding role in modern analytical sciences.

Low-intensity pulsed ultrasound enhances delivery of 30 nm Q10 for improving mental and memory disorder in APP/PS1 mice

Patients with Alzheimer's disease (AD) often experience mental and memory disorders with poor outcomes. Coenzyme Q10 can degrade formaldehyde (FA) and improve Alzheimer-related symptoms, but its ability to cross the blood-brain barrier (BBB) is limited. This study investigated whether low-intensity pulsed ultrasound (LIPUS) enhances 30 nm Q10 delivery and improve symptoms in AD model mice. Here, 30 nm Q10 was prepared by encapsulating Q10 in liposomes coupled with PEG, creating PEG-Q10@NPs under 30 nm in diameter. Wild-type mice and APPswe/PS1dE9 mice (a familial AD model) received 30 nm Q10 via intraperitoneal injection, or a combination of 30 nm Q10 and LIPUS (50 or 100 100 mW/cm2). Then the mice's anxiety-like and depression-like behaviors and biochemical index were evaluated. We found that the combination therapy of LIPUS at 100 mW/cm2 and 30 nm Q10 was more effective in ameliorating psychosis in AD mice than individual treatments with 30 nm Q10. This effectiveness was linked to higher levels of brain Q10, serotonin (5-HT), and dopamine (DA), along with lower levels of FA and plaques. Especially, excessive FA directly inactivated 5-HT and DA in vitro. The enhanced cellular uptake of Q10 and improved BBB permeability facilitated by LIPUS were confirmed in both cultured cells and wild-type mice. Unexpectedly, LIPUS at the different intensity only partially alleviated anxiety and depression symptoms and memory deficits in AD mice. Hence, this combination therapy of LIPUS and 30 nm Q10 is an innovative strategy for ameliorating mental and cognitive disorders in AD.

Opposite Roles of Co-enzyme Q10 and Formaldehyde in Neurodegenerative Diseases

Most of neurodegenerative diseases (NDD) have no cure. The common etiology of neurodegenerations is unclear. Air pollutant-gaseous formaldehyde is notoriously known to induce demyelination and cognitive impairments. Unexpectedly, an amount of formaldehyde has been detected in the brains. Multiple factors can induce the generation and accumulation of endogenous formaldehyde. Excessive formaldehyde can induce oxidative stress to generate H2O2; in turn, H2O2 promote formaldehyde production. Clinical investigations have shown that an abnormal high level of formaldehyde but low level of coenzyme Q10 (coQ10) was observed in patients with NDD. Further studies have proven that excessive formaldehyde directly inactivates coQ10, reduces the ATP generation, enhances oxidative stress, initiates inflammation storm, induces demyelination; subsequently, it results in neurodegeneration. Although the low water solubility of coQ10 limits its clinical application, nanomicellar water-soluble coQ10 exhibits positive therapeutical effects. Hence, nanopackage of coQ10 may be a promising strategy for treating NDD.

Degradation of FA reduces Aβ neurotoxicity and Alzheimer-related phenotypes

Dysregulation of formaldehyde (FA) has been implicated in the development of Alzheimer's Disease (AD). Elevated FA levels in Alzheimer's patients and animal models are associated with impaired cognitive functions. However, the exact role of FA in AD remains unknown. We now identified that oxidative demethylation at serine^8/26 of amyloid-beta protein (Aβ) induced FA generation and FA cross-linked with the lysine²⁸ residue in the β-turn of Aβ monomer to form Aβ dimers, and then accelerated Aβ oligomerization and fibrillogenesis in vitro. However, Aβ42 mutation in serine^8/26, lysine²⁸ abolished Aβ self-aggregation. Furthermore, Aβ inhibited the activity of formaldehyde dehydrogenase (FDH), the enzyme for FA degradation, resulting in FA accumulation. In turn, excess of FA stimulated Aβ aggregation both in vitro and in vivo by increasing the formation of Aβ oligomers and fibrils. We found that degradation of FA by formaldehyde scavenger-NaHSO₃ or coenzyme Q10 reduced Aβ aggregation and ameliorated the neurotoxicity, and improved the cognitive performance in APP/PS1 mice. Our study provides evidence that endogenous FA is essential for Aβ self-aggregation and scavenging FA could be an effective strategy for treating AD.

Accumulation of formaldehyde causes motor deficits in an in vivo model of hindlimb unloading

During duration spaceflight, or after their return to earth, astronauts have often suffered from gait instability and cerebellar ataxia. Here, we use a mouse model of hindlimb unloading (HU) to explore a mechanism of how reduced hindlimb burden may contribute to motor deficits. The results showed that these mice which have experienced HU for 2 weeks exhibit a rapid accumulation of formaldehyde in the gastrocnemius muscle and fastigial nucleus of cerebellum. The activation of semicarbazide-sensitive amine oxidase and sarcosine dehydrogenase induced by HU-stress contributed to formaldehyde generation and loss of the abilities to maintain balance and coordinate motor activities. Further, knockout of formaldehyde dehydrogenase (FDH^-/-) in mice caused formaldehyde accumulation in the muscle and cerebellum that was associated with motor deficits. Remarkably, formaldehyde injection into the gastrocnemius muscle led to gait instability; especially, microinfusion of formaldehyde into the fastigial nucleus directly induced the same symptoms as HU-induced acute ataxia. Hence, excessive formaldehyde damages motor functions of the muscle and cerebellum.

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 λ_ex/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.