A series of epoxy- and/or 20-oxime pregnanes were synthesized from commercially available pregnenolone. Compounds 1, 3, 7, 8 and 11-13 were evaluated for cytotoxicity activity towards LNCaP (androgen-dependent) and PC-3 (androgen-independent) prostate cancer cells. Compound 13 showed the highest activity on both LNCaP (IC(50) 15.17 microM) and PC-3 (IC(50) 11.83 microM) cell lines. Compound 11 showed weak activity on LNCaP cells (IC(50) 71.85 microM) and 8 showed the weak activity on PC-3 cells (IC(50) 68.95 microM), respectively. The 5alpha-reductase II (5AR2) inhibitory effects of compounds 1-3, 5 and 7-13 were investigated in a convenient screening model, in which compounds 5, 8, 11 and 12 were observed to be potential inhibitors of 5alpha-reductase, in particular, the 4-azasteroid 11, that also inhibited cell proliferation of androgen-dependent cells and 8, that in addition inhibited PC-3 cells more potently than LNCaP cells.