New Pimarane Diterpenoids Isolated from EtOAc-Extract of Apiospora arundinis Culture Medium Show Antibenign Prostatic Hyperplasia Potential

Three new pimarane diterpenoids, libertellenones U-W (1-3), together with libertellenone C (4) and myrocin A (5) were isolated from an EtOAc-extract of Apiospora arundinis culture medium. The chemical structures of the new compounds were elucidated using MS, NMR, and CD spectroscopic data. Benign prostatic hyperplasia (BPH), the abnormal and pathological proliferation of epithelial and stromal cells in prostatic tissues, is a common disease in middle-aged and elderly men. In this study, the anti-BPH effects of myrocin A (5) were evaluated using BPH-1 and WPMY-1 cells. Treatment with myrocin A (5) exerted antiproliferative effects in BPH-1 and dihydrotestosterone (DHT)-stimulated WPMY-1 cells. In BPH, treatment with myrocin A (5) significantly suppressed the mRNA levels of androgen receptor (AR) and its downstream targets nuclear receptor coactivator 1 (NCOA1), proliferating cell nuclear antigen (PCNA) and kallikrein-related peptidase 3 (KLK3). Additionally, DHT-stimulated WPMY-1 cells demonstrated an upregulated mRNA levels of AR, NCOA1, PCNA, and KLK3. However, treatment with myrocin A (5) resulted in suppression of the mRNA levels. Moreover, myrocin A (5) docked computationally into the binding site of the androgen receptor (−5.5 kcal/mol).