Discovery of novel 17-phenylethylaminegeldanamycin derivatives as potent Hsp90 inhibitors.

Twenty-six 17-phenylethylamine-modified geldanamycin derivatives were synthesized and evaluated for antiproliferation activity in human cancer cell lines, LNCaP and MDA-MB-231. Five derivatives (2j, 2q, 2v, 2x, and 2 y) showed excellent in vitro antitumor activities. Among them, compound 2 y was the most potent lead, with IC50 values of 0.27 ± 0.11 and 0.86 ± 0.23 μm for LNCaP and MDA-MB-231, respectively. In particular, compound 2 y was more active than its precursor geldanamycin against LNCap cells. Liver injury test in mice demonstrated that 2 y group showed no significant difference for serum alanine aminotransferase (ALT) activity versus vehicle control, indicating that 2 y was a promising antitumor candidate. Preliminary structure-activity relationship (SAR) and molecular dynamics (MD) simulations of this new series of geldanamycin derivatives were also investigated, suggesting a theoretical model of 17-phenylethylaminegeldanamycins binding to Hsp90.