Peroxynitrite scavenger FeTPPS effectively inhibits hIAPP aggregation and protects against amyloid induced cytotoxicity

Type 2 diabetes (T2D) is associated with pancreatic β-cell dysfunction, which can be induced by oxidative stress or/and the aggregation of human islet amyloid polypeptide (hIAPP). Therefore, ONOO− and hIAPP become the crucial targets of T2D treatment. Previously, we found heme could be an effective inhibitor of hIAPP aggregation. However, heme causes serious toxic effects on cells, tissues and organs through oxidative stress, which block it as a potential drug candidate for T2D treatment. 5,10,15,20-tetrakis(4-sulfonatophenyl) porphyrinato iron(III) chloride (FeTPPS), a water-soluble derivative of heme, is recognized as a high-efficient ONOO− decomposition catalyst, which is reported to have a great therapeutic potential in ONOO− -related diseases, including T2D. Here, we explored the potentiality of FeTPPS to be an inhibitor of hIAPP aggregation and the protective effects on cytotoxicity of hIAPP aggregation. It was found that the interaction between FeTPPS and hIAPP remarkably affected hIAPP fibrillation by both stabilizing hIAPP monomers and disaggregating the long fibrils into small oligomeric species. Furthermore, unlike heme, the addition of FeTPPS completely reversed the cytotoxicity and ROS level induced by hIAPP, which was consistent with its strong inhibitory activity. These results implied that FeTPPS could be a promising agent for the treatment of T2D.