Eriobotrya japonica Leaf Extract Ameliorates Benign Prostatic Hyperplasia by Regulating Inflammation

Eriobotrya japonica, a Rosaceae family plant, is cultivated in East Asia and possesses various biological activities. It has a long history of use in traditional medicine practices. Benign prostatic hyperplasia (BPH) is a common urological issue in aging men. Although its exact etiology remains unidentified, it is believed to be caused by a combination of factors such as aging, inflammation, and hormonal imbalance. This study examined the effects of E. japonica leaf 50% ethanol extracts (EJE) on human prostate epithelial BPH-1 cells and a BPH rat model developed via testosterone propionate (TP) injection. In BPH-1 cells, EJE treatment suppressed the proliferation of the cells in a dose-response relationship. In addition, mRNA expression levels of androgen receptor (AR), steroid 5 alpha-reductase type 2 (SRD5A2), and Bcl-2 were decreased, and Bax expression and the Bax/Bcl-2 ratio were increased by EJE treatment. In the in vivo experiment, castrated Sprague-Dawley (SD) rats were orally administered EJE at the following doses: 50-200 mg/kg of body mass. EJE administration reduced prostate weight, prostate ratio, serum dihydrotestosterone (DHT) levels, and serum testosterone levels. It also decreased intraprostatic DHT levels and 5α-reductase 2 expression. Histological analysis revealed a reduced epithelial thickness and increased lumen area in the EJE treatment group. Furthermore, the expression of AR, Bcl-2, tumor necrosis factor (TNF)-α, interleukin (IL)-8, IL-6, IL-1β, and cyclooxygenase-2 (COX-2) in prostate tissues was lowered by EJE administration. In conclusion, EJE effectively alleviated benign prostatic hyperplasia, both in cells and in animal models, by regulating inflammation, suggesting it is a potential candidate as a functional ingredient for alleviating BPH.