Urinary excretion of L-carnitine, acetyl-L-carnitine, propionyl-L-carnitine and their antioxidant activities after single dose administration of L-carnitine in healthy subjects

Neuroprotective Effects of Carnitine and Its Potential Application to Ameliorate Neurotoxicity

Carnitine is an essential metabolite that is absorbed from the diet and synthesized in the kidney, liver, and brain. It ferries fatty acids across the mitochondrial membrane to undergo β-oxidation. Carnitine has been studied as a therapy or protective agent for many neurological diseases and neurotoxicity (e.g., prolonged anesthetic exposure-induced developmental neurotoxicity in preclinical models). Preclinical and clinical data support the notion that carnitine or acetyl carnitine may improve a patient's quality of life through increased mitochondrial respiration, release of neurotransmitters, and global gene expression changes, showing the potential of carnitine beyond its approved use to treat primary and secondary carnitine deficiency. In this review, we summarize the beneficial effects of carnitine or acetyl carnitine on the central nervous system, highlighting protective effects against neurotoxicity-induced damage caused by various chemicals and encouraging a thorough evaluation of carnitine use as a therapy for patients suffering from neurotoxicant exposure.

Decreased total antioxidant capacity has a larger effect size than increased oxidant levels in urine in individuals with autism spectrum disorder

Oxidant/antioxidant imbalance may contribute to the pathophysiology of autism spectrum disorder (ASD). We assayed urinary levels of oxidative stress related biomarkers, hexanoyl-lysine (HEL), total antioxidant capacity (TAOC), the DNA methylation biomarker 8-hydroxy-2'-deoxyguanosine (8-OHdG), and plasma levels of superoxide dismutase (SOD), which is major antioxidant enzyme. We examined the relationship between these four biomarkers and social responsiveness in 20 individuals with ASD and in 11 healthy controls. The sex (ASD group, 7/13 vs. control group, 4/7) and age distributions (ASD group, 10.7 ± 5.0 years vs. control group, 14.7 ± 6.3 years) were not significantly different between the groups. Social responsiveness was assessed using the social responsiveness scale (SRS). We used standardized regression coefficients to measure the effect size. The ASD group exhibited significantly lower urinary TAOC levels and significantly elevated urinary HEL levels than the control group. Urinary 8-OHdG levels and plasma SOD levels were not significantly different between the groups. The ASD group showed significantly higher SRS scores than the control group. Plasma SOD levels correlated significantly with urinary TAOC levels. Standardized regression coefficients revealed that TAOC levels had a larger effect size than HEL levels in urine. This study firstly reveals that an imbalance between urinary HEL and TAOC levels in favor of urinary TAOC levels may contribute to impaired social responsiveness in individuals with ASD. Plasma SOD levels may also affect urinary TAOC levels.