BACKGROUND: Traditional Botanical Supplement-101 (TBS-101) is a newly developed proprietary botanical agent containing seven standardized botanical extracts, including: Panax ginseng, cranberry, green tea, grape skin, grape seed, Ganoderma lucidum and chamomile. Each of the components has been consumed either in the regular diet or as natural supplement. When used as a single agent, each of these seven botanicals has been implicated in chemoprevention and therapy in various types of cancer. The anticancer effect of TBS-101, with the specific combination of these anti-cancer botanicals for the treatment of prostate cancer (PCa), has not been tested. MATERIALS AND METHODS: The IC(50) and the effect of TBS-101 on the proliferation and apoptosis of PC-3 cells were determined. Tumor xenograft mice were generated by subcutaneously implanting PC-3 cells into mice and tumors were allowed to grow to different sizes before starting the treatment. The effects of TBS-101 on tumor growth were assessed by measuring tumor size and by histological, pathological and immunohistochemical analyses. A basic toxicity study was performed to test the tolerance of the mice to high doses of TBS-101. RESULTS: Treatment of the PC-3 cells with TBS-101 resulted in a dose-dependent inhibition of cell growth, with an IC(50) of 1.4 microg/ml. A concomitant induction of apoptosis in PC-3 cells treated with TBS-101 was also observed. Upon the treatment with TBS-101, all three groups of mice bearing moderate or large tumors showed significant inhibition of tumor growth and invasion. In contrast, control mice treated with vehicle alone had significant tumor growth and lymph node metastasis. In the basic toxicity studies, high doses of TBS-101 exerted no toxicity in healthy or tumor-bearing mice. CONCLUSION: The natural botanical agent TBS-101 has a good safety profile and significant anticancer activities in hormone-refractory PC-3 cells and large aggressive PC-3 tumors in a xenograft mouse model and has great potential for the treatment of aggressive prostate cancer