Purple rice extract inhibits testosterone-induced rat prostatic hyperplasia and growth of human prostate cancer cell line by reduction of androgen receptor activation.

The preventive effects of purple rice crude ethanolic extract (PRE) were firstly investigated on testosterone-induced benign prostatic hyperplasia (BPH) in castrated rats. As compared to vehicle-treated rats, lower prostate weights were found in the BPH rats that received PRE 1 g/kg bw. In addition, the PRE treatment down-regulated the androgen receptor (AR) expression in the dorsolateral prostate of those rats. In human prostate cancer cell line, LNCaP, PRE could reduce the cell growth, down-regulate the expression of AR and suppress prostate-specific antigen (PSA) secretion. Moreover, PRE also inhibited an activity of 5α-reductase from rat liver microsomes and the mutagenicity of Salmonella Typhimurium induced by standard mutagen. These results demonstrate that PRE altered testosterone-induced BPH in rats and retarded prostate cancer cell growth by modulating AR expression. It is therefore recommended that further investigation is undertaken into the chemopreventive potential of PRE in androgen-AR mediated diseases. PRACTICAL APPLICATIONS: This study revealed the mechanisms of purple rice extract on testosterone-induced rat benign prostatic hyperplasia. Such information, purple rice components show promise as an effective chemopreventive agent for prostatic hyperplasia prevention by alternating the influence of testosterone through its receptor. Thus, purple rice might be developed as food supplement for reduction of prostatic hyperplasia or cancer in elder men.