WS® 1541 (trade product: Prostagutt® forte) is a phytopharmaceutical drug combination containing a lipophilic extract from fruits of Sabal serrulata (WS® 1473) and an aqueous ethanolic extract from roots of Urtica dioica (WS® 1031). It is approved in Germany and several other countries for the symptomatic treatment of early stages of BPH in men. The aim of the present study was to investigate whether WS® 1541 exerts growth-inhibitory and anti-inflammatory actions in the prostate of Probasin-Prolactin (Pb-PRL) transgenic mice. The overexpression of prolactin in the prostate of these animals is accompanied by several features of the human disease, e.g. tissue hypertrophy, inflammation and lower urinary tract symptoms, indicating that it is a suitable animal model of BPH (Bernichtein et al, Prostate 75:706, 2015).
Male heterozygous Pb-PRL mice at an age of 6 months were randomly distributed (11-12 animals/group) to three doses of WS® 1541 (300, 600, 900 mg/kg/day), finasteride (5 mg/kg/day) or vehicle (olive oil 5 ml/kg/day) and treated orally for 28 consecutive days. Administration of WS® 1541 was well tolerated and caused a dose-dependently reduction of prostate weight that was statistically significant at the two higher doses. While WS® 1541 exerted an effect on all three lobes, the 5-alpha reductase inhibitor finasteride – which is widely used for the treatment of BPH - reduced the weight only of the ventral prostate. The growth-inhibitory activity of WS® 1541 was accompanied by an anti-inflammatory action as evidenced by the reduced infiltration of cells expressing the leukocyte common antigen CD45. In contrast, finasteride significantly increased the inflammatory status in all lobes. Since application of WS® 1541 did not interfere with transgene expression, the effects observed are entirely attributable to the intrinsic pharmacological action of the drug combination supporting the established therapeutic use of WS® 1541 in the treatment of BPH.