A Mitochondria-Targeted Phenylbutyric Acid Prodrug Confers Drastically Improved Anticancer Activities

Phenylbutyric acid (PBA) has been reported as a dual
inhibitor
of pyruvate dehydrogenase kinases (PDKs) and histone deacetylases
(HDACs), exhibiting anticancer effects. However, the low membrane
permeability and poor cellular uptake limit its access to the target
organelle, resulting in weak potencies against the intended targets.
Herein, we report the design and identification of a novel 4-CF3-phenyl triphenylphosphonium-based PBA conjugate (53) with improved in vitro and in vivo anticancer activities. Compound 53 exhibited an IC50 value of 2.22 μM against A375 cells, outperforming
the parent drug PBA by about 4000-fold. In the A375 cell-derived xenograft
mouse model, 53 reduced the tumor growth by 76% at a
dose of 40 mg/kg, while PBA only reduced the tumor growth by 10% at
a dose of 80 mg/kg. On the basis of these results, 53 may be considered for further preclinical evaluations for cancer
therapy.