Inhibition of 5 alpha-reductase in the rat prostate by Cimicifuga racemosa

Objectives: Prostate cancers and many thereof derived cell lines, as the LNCaP cells, grow androgen-dependent. In vivo testosterone is locally converted by 5 alpha-reductase to 5 alpha-dihydrotestosterone (5 alpha-DHT) which is the major androgenic principle in prostates and seminal vesicles. The occurrence of prostate cancer and growth of LNCaP cells can be effectively inhibited by finasteride, a synthetic 5 alpha-reductase inhibitor and by a black cohosh (Cimicifuga racemosa, CR) extract. In the present contribution we tested whether the aqueous/ethanolic C. racemosa extract BNO 1055 contains 5u-reductase inhibitors. Methods: Immature 24-day-old mate rats were fed with testosterone (T)-containing food and injected with 30mg CR BNO 1055 or 0.5 mg finasteride for 5 days. Average daily T-uptake was 39 mg/animal. Other animals remained untreated or received vehicle injections only. Results: In comparison to totally untreated rats the testosterone treatment increased weight of prostates and seminal vesicles 3-5-fold and this proliferation was largely and equipotently inhibited by finasteride and CR BNO 1055. 5 alpha-Dihydrotestosterone concentrations in prostate tissue extracts were also reduced by both compounds and the testosterone-upregulated androgen receptor and insulin like growth factor I gene expression inhibited in the seminals vesicles. Conclusion: Taken together, these results indicate that the CR extract BNO 1055 contains one or more potent 5 alpha-reductase inhibitors which may make this extract suitable for the prevention and treatment of prostate cancer and possibly of benign prostate hyperplasia (BPH). (c) 2006 Elsevier Ireland Ltd. All rights reserved.