My concern relates to its use as the positive control for the lipid-lowering assays. While oxidative stress and lipid metabolism are interconnected in NAFLD, the primary mechanism of action for direct lipid reduction, via AMPK phosphorylation and subsequent regulation of SREBP-1c, PPAR-α, and CPT-1, is distinct from NAC’s primary antioxidant role. The results in Figure 6B-C note that the peptides’ ability to lower TG and TC was “lower than that of NAC,” but this comparison may be problematic if NAC is not a potent or standard lipid-lowering agent in this specific model.
To ensure the robustness of the efficacy claims, could you please clarify:
1. Was NAC validated in your laboratory or in cited literature as an effective lipid-lowering agent in this exact FFA-induced HepG2 NAFLD model?
2. Was consideration given to using a more conventional positive control for hepatic lipid metabolism, such as a known AMPK activator (e.g., AICAR, metformin) or a drug used in NAFLD research (e.g., fenofibrate as a PPAR-α agonist), at least in parallel for the key lipid-lowering experiments?