Abstract:The active components in the extracts of Prinsepia utilis Royle leaves (QCJ) to combat benign prostatic hyperplasia (BPH) were screened and the underlying mechanisms were studied. The BPH model was built on the castrated rats by subcutaneous injection of testosterone propionate. The anti-BPH activity of QCJ and its derived fractions eluted from the macroporous resin at a low dose (1.8 g/kg/d) and a high-dose (5.4 g/kg/d), were evaluated using a testosterone propionate-induced castrated rat model and finasteride and Pule’an as positive controls. The results showed that QCJ and each fraction could alleviate the pathological changes in BPH rats. Among them, the 5% aqueous ethanol eluate from the macroporous resin (Fr. A) could reduce the contents of serum prostatic acid phosphatase (PACP) and dihydrotestosterone (DHT) concentration by 22.78% and 28.01% (p < 0.01) in BPH rats. The 40% ethanol eluate (Fr. B) could significantly alleviate the pathological changes in the BPH tissues and reduced the prostatic index, serum PACP content and DHT content by 7.69%, 32.91% and 56.59%, respectively (p < 0.01). Among all the fractions, Fr. B showed the most effective, and can significantly improved the pathological symptoms such as increased prostate index and prostate epithelial cell thickness in BPH rats. The underlying mechanism may be related to the inhibition of PACP and DHT production.