Structure of prolylrapamycin: confirmation through a revised and detailed NMR assignment study.

A complete and detailed characterization of Rapamycin (1) and Prolylrapamycin (2) has been conducted by homo- and hetero-nuclear NMR experiments in DMSO-d6 along with HRMS and FT-IR spectra and DSCs analyses. The NMR experiments allowed the assignment of every single proton and carbon atom belonging to the two structures and the definitive confirm of the presence of a pyrrolidine ring in Prolylrapamycin (2) in place of the piperidine ring that characterizes the structure of Sirolimus.

Chiral resolution and pharmacological characterization of the enantiomers of the Hsp90 inhibitor 2-amino-7-[4-fluoro-2-(3-pyridyl)phenyl]-4-methyl-7,8-dihydro-6H-quinazolin-5-one oxime.

Heat-shock protein 90 (Hsp90) is a molecular chaperone involved in the stabilization of key oncogenic signaling proteins, and therefore, inhibition of Hsp90 represents a new strategy in cancer therapy. 2-Amino-7-[4-fluoro-2-(3-pyridyl)phenyl]-4-methyl-7,8-dihydro-6H-quinazolin-5-one oxime is a racemic Hsp90 inhibitor that targets the N-terminal adenosine triphosphatase site. We developed a method to resolve the enantiomers and evaluated their inhibitory activity on Hsp90 and the consequent antitumor effects. The (S) stereoisomer emerged as a potent Hsp90 inhibitor in biochemical and cellular assays. In addition, this enantiomer exhibited high oral bioavailability in mice and excellent antitumor activity in two different human cancer xenograft models.