Serenoa repens extracts: In vitro study of the 5α-reductase activity in a co-culture model for benign prostatic hyperplasia

Objectives. Benign Prostatic Hyperplasia (BPH) is a form of benign tumor that occurs in humans mainly with ageing. It affects more than 50% of over 50 years old males and it is characterized by an increased synthesis of dihydrotestosterone (DHT), due to the 5 alpha-reductase activity. The BPH therapeutic approach mainly uses 5 alpha-reductase inhibitors, such as the active compounds present in the extracts deriving from species Serenoa repens. Many lipidosterolic extracts are available on the market, which are obtained with different solvents, among them ethanol is recognized as non-toxic and has less handling risks than hexane. The purpose of the present experimental study was to investigate in-vitro the potency of an ethanol extract of S. repens comparing it with an n-hexane one. Materials and methods. Two different lipido-sterolic extracts of S. repens have been tested: ethanol extract and n-hexane extract, two batches for each one. The inhibitory action of the extract was evaluated estimating in-vitro the activity of enzyme 5 alpha-reductase type I (5 alpha-RI), which was mainly active under the experimental condition of pH 7.5. DHT amount, synthesized from testosterone (1 mu M), was evaluated in a co-culture model of epithelial cells and fibroblasts resulting from prostatic biopsy of a patient with BPH. Results. The analysis of the resulting dose-response curves showed that the entire S. repens extracts inhibited the 5 alpha-RI showing no difference between the two kinds of extract or between the batches. The resulting IC50 values were the following: 8.809 (95% CI = 5.133-15.56) and 9.464 (95% CI = 5.09418.27) for ethanol extracts; 11.08 (95% CI = 6.389-19.98) and 12.72 (95% CI = 7.758-21.53) for n-hexane extracts. Conclusions. The potency of ethanol extracts of S. repens was comparable with the one of n-hexane extracts