Development of amphiphilic metal-binding short peptides that change the dispersibility of paclitaxel upon complexation with intermediate metal(II) ions

Abstract In the present study, a novel amphiphilic short peptide KHHAAAAAAA (abbreviated as KHHA7) and reference peptides were synthesized as dispersants for poorly water-soluble drugs. The peptides have a hydrophilic domain consisting of a lysine and two histidines, and a hydrophobic domain consisting of seven relatively hydrophobic amino acids, alanine and valine. Additionally, two histidine residues form a stable complex with intermediate metal ions such as Cu(II) and Ni(II). The peptide KHHA7 was chemically synthesized by the Fmoc solid-phase synthesis method. The water dispersibility of a poorly water-soluble anticancer drug paclitaxel (Ptx) was enhanced by the complexation with KHHA7. Additionally, the dispersibility of Ptx complexed with KHHA7 was further enhanced in the presence of Cu(II) or Ni(II). Furthermore, the dispersibility of the ternary (Ptx-KHHA7-Cu(II)) complex decreased in the presence of a stronger chelating agent, EDTA. From the results, KHHA7 was found to act as a dispersant of Ptx, which changes its functionality upon complexation with metal ions.