Total synthesis as a resource in drug discovery: the first in vivo evaluation of panaxytriol and its derivatives.

[structures: see text] We have conducted key preliminary studies into the in vitro and in vivo cytotoxicity of panaxytriol. Through total synthesis, we prepared and evaluated several synthetic panaxytriol analogues, each of which exhibited enhanced cytotoxicity relative to the natural product. Consequently, we have begun to chart the first in vitro SAR map for the compound, which suggests that the C3 hydroxyl functionality is not critical for biological activity and that, in fact, engagement of the C9-C10 diol as an acetonide actually leads to notably enhanced cytotoxicity. Furthermore, through in vivo investigations, we demonstrated that panaxytriol and panaxytriol acetonide (12) moderately suppress tumor growth with little or no toxicity. Finally, preliminary in vitro evaluation of panaxytriol indicates that it possesses neurotrophic activity.