Rational design, synthesis and biological evaluation of triphenylphosphonium-ginsenoside conjugates as mitochondria-targeting anti-cancer agents.

ABSTRACT

In anti-cancer therapy, targeting a single gene or a single metabolic pathway usually cannot effectively cure cancer, while targeting cellular mitochondria might be effective based on the role of mitochondria in the occurrence and development of cancer. Anti-cancer study on ginsenosides AD-1, AD-2 and PD have proved that they have broad spectrum anti-cancer activities in vitro and in vivo. However, they are not active at sufficiently low concentration, and their lower selectivity and cell permeability hindered therapeutic applications. In the present study, AD-1, AD-2 and PD are incorporated with triphenylphosphonium at the OH group in C-3 position through different length of alkyl chains, with the aim of targeting mitochondria and improving the efficacy and selectivity of parent compounds. Biological studies suggested that most of the conjugates had enhanced anti-proliferative activity, in particular, conjugate 1f had an IC50 value of 0.76 µM against MCF-7 cells while showed a high degree of selectivity to MCF-7 cells. In addition, 1f was obviously increased accumulation in the mitochondria, and induced apoptosis, elevated reactive oxygen species (ROS) level and caused mitochondrial membrane potential collapse in MCF-7 cells. Further study revealed that ROS-related mitochondrial translocation of p53 was also involved in 1f-induced mitochondrial apoptotic pathway. The results demonstrated that 1f could be a promising lead for the development of mitocans. These findings also provide a reference for the development of ginsenoside for mitochondria-targeted anti-cancer drugs.