Maple syrup urine disease (MSUD) is a disorder of
branched-chain amino acids (BCAA). The defect in the branched-chain α-keto
acid dehydrogenase complex activity leads to an accumulation of these compounds and their corresponding α-
keto-acids and α-
hydroxy-acids. Studies have shown that oxidative stress may be involved in neuropathology of MSUD.
L-carnitine (L-car), which has demonstrated an important role as
antioxidant by reducing and scavenging
free radicals formation and by enhancing the activity of
antioxidant enzymes, have been used in the treatment of some metabolic rare disorders. This study evaluated the oxidative stress parameters, di-
tyrosine,
isoprostanes and
antioxidant capacity, in urine of MSUD patients under
protein-restricted diet supplemented or not with L-car capsules at a dose of 50 mg kg(-1) day(-1). It was also determined urinary α-keto
isocaproic acid levels as well as blood free L-car concentrations in blood. It was found a deficiency of
carnitine in patients before the L-car supplementation. Significant increases of di-
tyrosine and
isoprostanes, as well as reduced
antioxidant capacity, were observed before the treatment with L-car. The L-car supplementation induced beneficial effects on these parameters reducing the di-
tyrosine and
isoprostanes levels and increasing the
antioxidant capacity. It was also showed a significant increase in urinary of α-ketoisocaproic
acid after 2 months of L-car treatment, compared to control group. In conclusion, our results suggest that L-car may have beneficial effects in the treatment of MSUD by preventing oxidative damage to the cells and that urine can be used to monitorize oxidative damage in patients affected by this disease.