A supramolecular complex of hydrazide-pillar[5]arene and bisdemethoxycurcumin with potential anti-cancer activity.

Pillar[5]arene complexes of the naturally occurring compound bisdemethoxycurcumin (BDMC) were acquired for improving the water solubility and stability of BDMC. As a family member of curcuminoid compounds, BDMC has many interesting therapeutic properties. However, its low aqueous solubility and stability resulted in poor availability and restricted the clinical efficacy. Pillar[5]arenes with hydrophilic ends and a hydrophobic cavity could include with BDMC based on size matching. The synthesized hydrazide-pillar[5]arene (HP5A) and BDMC had a strong host-guest interaction with a 1:1 binding stoichiometry. Furthermore, the HP5A ⊃ BDMC complex could self-assemble into well-defined fibers in water/ethanol solution. This supramolecular complex worked well in vitro for inhibiting the proliferation of hepatoma carcinoma cells HepG2. Remarkably, this method of complexation with pillar[5]arenes visibly reduced the undesirable side effects on normal cells without weakening the anti-cancer activity of the drugs. We expected that the obtained host-guest complex and fibrous assembly would provide a promising platform for delivering drugs with low water solubility.