Programa de Pós-Graduação em Ciências Farmacêuticas, Faculdade de Farmácia, UFRGS, Av. Ipiranga, 2752, CEP 90610-000 Porto Alegre, RS, Brazil; Serviço de Genéstica Médica, HCPA, R. Ramiro Barcelos, 2350, CEP 90035-003 Porto Alegre, RS, Brazil.
Programa de Pós-Graduação em Ciências Farmacêuticas, Faculdade de Farmácia, UFRGS, Av. Ipiranga, 2752, CEP 90610-000 Porto Alegre, RS, Brazil; Serviço de Genéstica Médica, HCPA, R. Ramiro Barcelos, 2350, CEP 90035-003 Porto Alegre, RS, Brazil.
Toxicol In Vitro. 2019 Jun;57:194-202. doi: 10.1016/j.tiv.2019.03.007. Epub 2019 Mar 7.
Maple syrup urine disease (MSUD) is an inherited deficiency of the branched-chain α-keto dehydrogenase complex, characterized by accumulation of the branched-chain amino acids (BCAAs) and their respective branched chain α-keto-acids (BCKAs), as well as by the presence of alloisoleucine (Allo). Studies have shown that oxidative stress is involved in the pathophysiology of MSUD. In this work, we investigated using the comet assay whether Allo, BCAAs and BCKAs could induce in vitro DNA damage, as well as the influence of l-Carnitine (L-Car) upon DNA damage. We also evaluated urinary 8-hydroxydeoguanosine (8-OHdG) levels, an oxidative DNA damage biomarker, in MSUD patients submitted to a restricted diet supplemented or not with L-Car. All tested concentrations of metabolites (separated or incubated together) induced in vitro DNA damage, and the co-treatment with L-Car reduced these effects. We found that Allo induced the higher DNA damage class and verified a potentiation of DNA damage induced by synergistic action between metabolites. In vivo, it was observed a significant increase in 8-OHdG levels, which was reversed by L-Car. We demonstrated for the first time that oxidative DNA damage is induced not only by BCAAs and BCKAs but also by Allo and we reinforce the protective effect of L-Car.
枫糖尿症（MSUD）是一种遗传性支链α-酮脱氢酶复合物缺乏症，其特征是支链氨基酸（BCAAs）及其相应的支链α-酮酸（BCKAs）的积累，以及异亮氨酸（Allo）的存在。研究表明氧化应激参与了 MSUD 的病理生理学。在这项工作中，我们使用彗星试验研究了 Allo、BCAAs 和 BCKAs 是否可以诱导体外 DNA 损伤，以及左旋肉碱（L-Car）对 DNA 损伤的影响。我们还评估了接受限制饮食补充或不补充 L-Car 的 MSUD 患者的尿 8-羟基脱氧鸟苷（8-OHdG）水平，这是一种氧化 DNA 损伤生物标志物。所有测试浓度的代谢物（单独或一起孵育）均诱导体外 DNA 损伤，而与 L-Car 共同处理可降低这些影响。我们发现 Allo 诱导了更高的 DNA 损伤类别，并验证了代谢物协同作用诱导的 DNA 损伤的增强。在体内，观察到 8-OHdG 水平显著增加，而 L-Car 可逆转这种增加。我们首次证明氧化 DNA 损伤不仅由 BCAAs 和 BCKAs 引起，而且由 Allo 引起，并且我们加强了 L-Car 的保护作用。
