Ailanthone is a quassinoid that has been found in Ailanthus and has diverse biological activities. It is active against the P. falciparum strains HB-3 and Dd-2 in vitro (IC50s = 0.003 and 0.037 μg/ml, respectively). Ailanthone is phytotoxic, inhibiting radish seed germination by 88% when used at a concentration of 1 mM. It inhibits dihydrotestosterone-induced androgen receptor transcriptional activity (IC50 = 69 nM in a reporter assay), as well as the growth and colony formation of LNCaP and 22RV1 androgen receptor-expressing cells, but not androgen receptor-negative PC3 and DU145 cells, when used at a concentration of 0.1 μM. Ailanthone (2 mg/kg) reduces tumor volume in 22Rv1, LNCaP, and VCaP castration-resistant prostate cancer (CRPC) mouse xenograft models.
