Silibinin induces protective superoxide generation in human breast cancer MCF-7 cells

Abstract

The pharmacological activity of polyphenolic silibinin from milk thistle (Silybum marianum) is primarily due to its antioxidant property. However, this study found that silibinin promoted sustained superoxide (O₂^·–) production that was specifically scavenged by exogenous superoxide dismutase (SOD) in MCF-7 cells, while the activity of endogenous SOD was not changed by silibinin. Previous work proved that silibinin induced MCF-7 cell apoptosis through mitochondrial pathway and this study further proved that O₂^·– generation induced by silibinin was also related to mitochondria. It was found that respiratory chain complexes I, II and III were all involved in silibinin-induced O₂^·– generation. Moreover, it was found that silibinin-induced O₂^·– had protective effect, as exogenous SOD markedly enhanced silibinin-induced apoptosis.

Keywords::

• Silibinin
• O₂^·–
• SOD
• mitochondria

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

This paper was first published online on Early Online on 20 June 2009.