Chemical characterization of fraction F5. (A) LC-MS analysis of fraction F5. Positive ESI-MS m/z signals are shown. The chemical structure of amygdalin was generated by ACD/Chem Sketch software (http://www.acdlabs.com/resources/freeware/chemsketch/). (B) HPLC verification of amygdalin as the active compound. The fraction F5, amygdalin standard, and F5-amygdalin mixture were sequentially analyzed by reverse-phase HPLC on a C18 column under the same conditions. (C) RT-PCR verification of commercial amygdalin for induction of follistatin mRNA. HepG2 cells were treated with commercial amygdalin at the indicated concentrations for 24 h. The expression of follistatin mRNA was detected by RT-PCR.