CBS and hyperlipidemia: Previous studies showed that the hyperlipidemia led to a significant decrease in cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE) activities in the liver and blocked the Hcy conversion to Cys, resulting in not only the upstream accumulation of Hcy but also downstream deficiency of Cys and subsequent reduction of antioxidant GSH synthesis [49].