The object of this paper is to summarize for the past two years the most recent development in the field of
prostate cancer and
5 alpha-reductase inhibitors. In addition we are also including some results on the synthesis and pharmacological evaluation of new steroidal compounds developed in our laboratory. Most of the new steroidal derivatives are based on the
progesterone skeleton and showed a high inhibitory activity for the
enzyme 5 alpha-reductase. Presently, similar compounds are used for the treatment of
androgen dependent diseases such as:
hirsutism,
androgenic alopecia,
benign prostatic hyperplasia and
prostate cancer.
Dihydrotestosterone 2 (Fig. 1) a 5 alpha-reduced metabolite of
testosterone 1 has been implicated as a causative factor for the progression of these diseases, largely through the clinical evaluation of males who are genetically deficient of the
enzyme steroid 5 alpha-reductase. As a result of this study, the inhibition of this
enzyme has become a pharmacological strategy for the design and synthesis of new antiandrogenic drugs. The advent of
finasteride 7 (Fig. 3) a
5 alpha-reductase inhibitor has greatly alleviated the symptoms associated with
benign prostatic hyperplasia. In our laboratory, we recently synthesized several new 16 beta-methylpregnadiene-3,20-diones: 40, 41 (Fig. 8), 16 beta-phenylpregnadiene-3,17a-dione derivatives 46 and 47 (Fig. 9) and 49 (C-4 bromoderivative) (Fig. 11), 52-56 (Fig. 13). The analogue pregnatriene derivatives were also prepared: 44, 45 (Fig. 9) 50, 51 (Fig. 11) and 57-60 (Fig. 13) These compounds were evaluated as
5 alpha-reductase inhibitors in the following
biological models: Penicillium crustosum broths, the flank organs of gonadectomized male hamsters, the incorporation of radiolabeled
sodium acetate into
lipids, the effect of the new
steroids on the reduction of the weight of the seminal vesicles and on the in vitro metabolism of [3H]T to [3H]DHT in seminal vesicles of homogenates of gonadectomized male hamsters. All trienones 44, 45, 50, 51 and 57-60 in all
biological models showed consistently a higher
5 alpha-reductase inhibitory activity than the corresponding dienones: 40, 41, 46, 47, 49 and 52-56. We believe that with these compounds the
5 alpha-reductase enzyme is inactivated by an irreversible Michael type addition of the nucleophilic portion of the
enzyme to the conjugated double bond of the
steroid. The trienones having a more coplanar structure react faster with the
enzyme thus showing a higher inhibitory activity.