Interactions of a herbal combination that inhibits growth of prostate cancer cells.
OBJECTIVE
PC SPES is an eight-component herbal product marketed for the treatment of prostate cancer. The manufacturer of PC SPES claims that the herbal combination is a synergistic blend, but the purported synergy has never been tested. We examined the interaction in cell culture of these eight individual herbal components by the use of an isobologram.


METHODS
US patent no. 5,665,393 (1997) for PC SPES was acquired, and each of the eight herbal components described was acquired, properly identified, and extracted by 95% ethanol. The extracts were tested for cytotoxicity to PC 3 human prostate cancer cells in culture by the MTT (3-[4,5-dimethythiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay. Seven combinations of herbal extracts were made, varying in the proportion of the most cytotoxic herbal extract, that of Panax notoginseng. The interactions of P. notoginseng with the other seven herbs were evaluated through the use of an isobologram.


RESULTS
In all seven herbal combinations, P. notoginseng was found to be antagonistic with the other seven herbal components in the cytotoxicity assay ( P values: 0.09, 0.12, 0.12, 0.33, 0.45, 0.56, and 0.76).


CONCLUSIONS
The interaction between the most cytotoxic herbal component of a widely used herbal product and the other seven components was antagonistic. Herbal combinations are no different from traditional combination pharmacotherapy. If herbal combinations are able to achieve antagonism, then theoretically they can achieve synergism if combined properly.
Chung
Vinh Q
VQ
Harvard Medical School, Unit 105, 111 Gainsborough, Boston, MA 02115, USA. vqchung@post.harvard.edu
Tattersall
Martin
M
Cheung
H T Andrew
HT
D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D004357:Drug Synergism; D004359:Drug Therapy, Combination; D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D006801:Humans; D008297:Male; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000473:pathology
D004365:Drugs, Chinese Herbal