Synthesis and anti-tumor evaluation of novel 25-hydroxyprotopanaxadiol analogs incorporating natural amino acids

► A series of 25-OH-PPD analogs incorporating natural amino acids have been synthesized. ► Combining an ester group combined with the presence of an amino acid moiety led to a 10-fold improved anti-tumor activity. ► Some compounds showed stronger anti-tumor activities than 5-Fu in vitro.