TITLE:
Uromedic® Pumpkin Seed Derived Δ7-Sterols, Extract and Oil Inhibit 5α-Reductases and Bind to Androgen Receptor in Vitro
AUTHORS:
Stefan Heim, Stephanie Seibt, Heike Stier, Margret I Moré
KEYWORDS:
5-Alpha-Reductases 5α-R1 and 5α-R2, Androgen Receptor, Dihydrotestosterone, Uromedic® Pumpkin Seed Oil and Soft Extract, (Delta-7) Δ7-Sterols
JOURNAL NAME:
Pharmacology & Pharmacy,
Vol.9 No.6,
June
29,
2018
ABSTRACT: Dihydrotestosterone (DHT) is implicated in the development of benign
prostate hyperplasia (BPH). We investigated if Uromedic? pumpkin (variety of Cucurbita pepo L. convar.
citrullinina GREB. var. styriaca GREB) seed soft extract (active
ingredients of GRANUFINK? Prosta forte 500 mg), seed oil and isolated Δ7-sterols could inhibit the conversion
of [1,2,6,7-3H(N)]-testosterone to DHT
by 5α-reductases. Also, we tested
competition with [3H]-DHT for binding to the androgen receptor (AR).
Pumpkin seed oil and pumpkin seed soft extract were identified as moderately
active inhibitors of 5α-R1 and 5α-R2, with almost similar inhibitory capacities
(IC50 5 mg/ml for 5α-R1 and about IC50 = 6 mg/ml
for 5α-R2). The isolated Δ7-sterols
were more active inhibitors (IC50 = 0.3
mg/ml for 5α-R1, IC50 = 1.0
mg/ml for 5α-R2). All
three test compounds bound to the AR dose-dependently, with strong binding by
Δ7-sterols (IC50 = 0.2
mg/ml) and weaker binding by pumpkin seed oil (IC50 = 0.4
mg/ml) and pumpkin seed soft extract (IC50 = 1.1
mg/ml). We propose that inhibition of 5α-reductases
and competitive binding to the AR are mechanisms of action, by which the
Uromedic? pumpkin seed derived test compounds, most specifically Δ7-sterols,
counteract DHT and thereby exert clinically positive effects on the prostate,
as well as bladder-strengthening effects.