Crotonianoids A-C, Three Unusual Tigliane Diterpenoids from the Seeds of Croton tiglium and Their Anti-Prostate Cancer Activity.

Crotonianoids A-C ( 1 - 3 ), three unusual tigliane diterpenoids, were isolated from the seeds of Croton tiglium . Compound 1 is a 13,14:13,15- diseco -tigliane featuring a unique spiro[bicyclo[5.3.0]decane-2,5'-2'(3' H ,4' H )-furanone] core; 2 is a 13,15- seco -tigliane incorporating a rare peroxide bridge between C-13 and C-15; and 3 is the first example of a phorbol ester with a 10 R -configuration. Their structures were determined by spectroscopic, computational, and X-ray diffraction methods. Compounds 1 and 2 markedly inhibited the growth and survival of prostate cancer cell C4-2B at micromolar concentrations and induced cell apoptosis. Mechanistic study revealed that 1 and 2 could suppress androgen receptor (AR) signaling pathway by promoting the degradation of AR protein.