1Departamento de Sistemas Biológicos y de Producción Agrícola y Animal, Universidad Autónoma Metropolitana-Xochimilco, Calzada del Hueso 110, Colonia Villa Quietud, Coyoacán, México
2Hospital General de México, Dr. Balmis. 48, Doctores, Cuauhtémoc, México
β-sitosterol (SIT) improves symptoms and urinary flow parameters in treating benign prostatic hyperplasia. Normal and abnormal prostate growth is driven by the androgen dihydrotestosterone (DHT) formed from testosterone (T) by the catalytic action of the steroid 5α-reductase type 1/2 (SRD5A1/2). The effect of SIT as an inhibitor of the SRD5A activity in the human prostate has scarcely been studied.
This study aimed to determine the effect of SIT as an inhibitor of the activity of SRD5A2. So, the concentration of SIT was assessed, which blocks 50% of its activity (IC50). The IC50 value was 130 nM for 5RD5A2.
Additionally, the kinetic parameters of 5RD5A2 activity were calculated from the plots of T concentration versus DHT formed in the presence or absence of SIT. Kinetic parameters indicated a DHT formation rate of 27.54 ± 2.72 ng/mg protein/h both in the absence and the existence of SIT. At the same time, Km values were 8.03 ± 0.67 µM in the absence of the inhibitor, 20.8 ± 5.6 µM in the presence of SIT, 0.7 µM and 46.94 ± 8.8 µM in the presence of SIT, 1.4 µM.
The pharmacological effect of SIT was compared with that of finasteride on the hamster prostate. Results indicated that T-treatment increased the prostate weight of castrated hamsters compared to the vehicle-treated neutered control. The SIT plus T treatment decreased this gland's weight similarly to the T plus finasteride.
Keywords: β-Sitosterol; Type 2 5α-Reductase; Human Prostate; Finasteride; Competitive Inhibitor
Marisa Cabeza.,et al. β-Sitosterol as a Competitive Inhibitor of the Human Type 2 5α- Reductase. EC Pharmacology and Toxicology 11.6 (2023): 17-27.
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