Testosterone 5α-reductase inhibition by free fatty acids from Sabal serrulata fruits

The inhibition of testosterone 5oc-reductase (EC 1.3.99.5) (5αR) in vitro by lipophilic extracts from Sabal serrulata fruits effective on Benign Prostatic hyperplasia (BPH) treatment is due entirely to free fatty acid content. In order to find out structure-inhibition activity relationships of the action of free fatty acids on the enzyme, we investigated the influences of chain-length, esterification, saturation degree, and oxidation on fatty acid 5aR inhibition activity. For fatty acid-like 5αR inhibition a strongly polar end-group and a molecular skeleton allowing nonpolar interactions with the enzyme are required. 5αR activity in prostate tissue may be influenced by lipid environment.