Search

Type 2 diabetes mellitus (T2DM) is a fatal disorder disease that is characterized by substantial β-cell mass reduction in the context of insulin deficiency. Previous researches have demonstrated that human islet amyloid polypeptide (h-IAPP), an oligopeptide monomer with 37 amino acid residues, induces apoptotic cell-death in β-cells and causes a development of T2DM. Previous studies have also shown that fibrils, which are the final form of aggregated h-IAPP, are not necessarily the most toxic form of amyloid protein in general. Oligomers may induce βcell apoptosis. Therefore, tremendous efforts have been conducted to develop drugs which prevent h-IAPP from forming oligomers. For instance, the use of oligomerspecific antibodies has been investigated, as well as the use of Cu(II) ion, which prevents h-IAPP from forming the βsheet conformers, and cleavage agents with Co(III) cyclen and Cu(II) cyclen. Cleavage agent with Cu(II) cyclen has been proposed as novel catalytic drug. Candidates for catalytic drug are mainly composed of two parts. One part is the catalytic group that hydrolyzes the peptide bond of h-IAPP. This part is composed of Cu(II) cyclen complex, which allows for secreted Cu(II) ions to act as oligomer inhibitors. The other part is the binding group that binds to h-IAPP through hydrophobic interactions. In regards to the hydrolysis reaction by Cu(II) cyclen complex, reaction time is critical and closely connected with the binding group’s capacity since the cleavage agent cleaves only the oligomer form and has limited reaction time. Therefore, it is necessary to synthesize the catalytic drug candidate with the other binding group. Proposed binding group is I-Box-derived one. Benzothiazoleanilines (BTAs) functional group has higher affinity for the hydrophobic amyloid than I-Box(2-(4'-dimethylaminophenyl)-6-iodobenzoxazole) and BTAs also have a ability to cross the blood-brain barrier (BBB) well. Figure 1 shows the proposed structure of Cu(II) cyclen cleavage agent with BTA-derived binding group (Fig. 1). New Cu(II) cleavage agent with BTA-derived binding group was synthesized and the efficiency of this noble agent for h-IAPP cleavage was tested. Figure 2 shows that the MALDI-TOF TOF MS spectrum of fragmentation pattern when h-IAPP was incubated with new Cu(II) cleavage agent with BTA-derived binding group. According to the previous literatures, residues 20-29 and 30-37 of h-IAPP (37mer) are considered as amyloidogenic region. Peaks shown in Figure 2 indicate the fragments of h-IAPP. This spectrum demonstrates that highly amyloidogenic regions of h-IAPP can exist as dissolved form in solution. This indicates that self aggregation of h-IAPP can be inhibited by this noble agent. In our previous study, we

Researches on the discovery of drugs against amyloidogenic proteins or oligopeptides which cause amyloidoses, such as AD (Alzheimer disease), type 2 diabetes mellitus, Parkinson’s disease, and mad cow disease, have focused on reducing the level of amyloid formation, cleaving amyloidogenic peptides, or blocking aggregation with organic molecules that selectively bind and inhibit aggregation and fibril formation.