Homopiperazine-rhodamine B adducts of triterpenoic acids are strong mitocans.

Parent pentacyclic triterpenoic acids such as ursolic-, oleanolic, glycyrrhetinic, betulinic and boswellic acid were converted into their acetylated piperazinyl amides that were coupled with rhodamine B. SRB assays to evaluate their cytotoxicity showed all of these triterpene-homopiperazinyl-rhodamine adducts 16-20 being highly cytotoxic for a panel of human tumor cell lines even in nanomolar concentrations while being significantly less cytotoxic for non-malignant cells. Interestingly enough, these compounds were even more cytotoxic than previously prepared piperazinyl analogs, thus making the homopiperazinyl spacer a very interesting scaffold for the development of biologically active compounds. Extra staining experiments showed that the cytostatic effect of compounds 18 and 20 onto A2780 cancer cells is due to their ability to act as a mitocan.