Extracts of the Phellodendron amurense tree commonly found in Asia have been used in traditional Chinese medicine for centuries for their astringent, anti-diarrheal and anti-inflammatory properties. Until now, Next Pharmaceuticals has marketed its branded product Nexrutine for inflammation and the relief of pain without causing gastrointestinal irritation that is a common side effect of drugs, including aspirin.
But the results of the new two-year study using the ingredients, conducted at the University of Texas' department of urology, could mean it is suitable for use in a new area.
"A reduction in prostate cancer progression using an inexpensive and safe dietary supplement such as Nexrutine is very exciting," said lead researcher Dr Pratap Kumar.
In the US around 230,000 men are diagnosed with prostate cancer each year, of which 30,000 die. However the disease has a long latency period, which the researchers say "provides opportunities for intervention with strategies including the use of dietary phytochemicals."
Phytochemicals previously implicated in prostate cancer prevention include genistein from soy, resveratrol from grapes and peanuts, curcumin, and green tea polyphenols.
"We are very excited about the results… and are in the process of setting up clinical trials as the next step," said Next president and CEO Bob Garrison. "This research indicates that Nexrutine could make an important contribution in the management of prostate cancer."
His optimism is based on findings published in the June issues of the journal Neoplasia (Vol 8, No 6, pp 523-533).
Dr Kumar and team initiated the study as a first step towards developing botanicals as prostate cancer preventatives, encouraged by epidemiological evidence suggesting that plant-based diets can reduce the risk of prostate cancer.
"Very little information is available concerning the use of botanicals in preventing prostate cancer," they wrote.
For their in vitro experiments they used a stock solution of Nexrutine with a concentration 1mg/ml, which was then diluted in growth medium to concentrations of one to 10 micrograms/ml.
They saw that the solution inhibited the proliferation of tumor cells by inducing apoptosis (cell death) - both androgen-responsive and androgen-independent cells - and to inhibit cancer cell growth by affecting survival signaling. The Nexrutine seemed to alter some of the main molecules associated with these processes, such as Akt kinase and transcription factor CREB.
In the time between completion of the study and publication, the team already initiated studies to identify the biologically active principle and the molecular pathways that regulate apoptotic response.