Jamaican spice fights cancer

The Jamaican allspice is known for flavouring cuisines around the world with a blend of cinnamon, cloves, nutmeg, pimento and pepper, but according to a new study by University of Miami's Miller School of Medicine researchers in Florida, United States, (US) the aromatic spice could be known one day for impeding the growth of, or maybe even preventing, prostate cancer, the number-two cancer-killer of men in the US.

In the study published online last month in the Oxford Journals' Carcinogenesis and led by Bal L. Lokeshwar, PhD, professor of urology and radiation oncology and co-director of research in the Department of Urology, researchers demonstrated that Ericifolin, a complex compound in the allspice berry, Pimenta dioica, significantly slows the growth of prostate cancer tumours by suppressing the androgen receptor (AR). A molecule central to the growth and metastasis of prostate cancer, AR enables prostate cancer cells to survive even after hormone therapy, which along with surgery and radiation is the standard treatment for prostate cancer.

"Androgen receptor, or AR for short, is the principal drug target for the treatment of prostate cancer, but there is no drug that completely eliminates AR. This complex compound in allspice seems to do that," Lokeshwar said.

"The most interesting data show that it actually kills tumour cells which express the very specific prostate cancer marker, the androgen receptor. That is not to say that people should start eating allspice with every meal, but there exists the potential that the slow and steady consumption of this chemo-dietary agent may slow or even prevent prostate cancer."

For now, Lokeshwar and his study team, including first author Shamaladevi Nagarajarao, PhD, a postdoctoral research associate, and Lei Zhang, a graduate student, have demonstrated that Ericifolin kills prostate cancer cells and reduces tumour growth by more than 50 per cent in animal models, specifically mice that were injected with prostate cancer cells, then, either fed or injected daily doses of an aqueous allspice extract.

"To our surprise, it worked very well," Lokeshwar said. "It was surprising because lots and lots of products kill cells in the test tube, but they are not effective when consumed or injected in animal models. In this case, the tumours did not disappear, but they grew about 50 per cent more slowly with both methods. Further, these mice did not exhibit any obvious toxicity associated with other anticancer drugs."

exploring anticancer activities

Next the researchers hope to determine whether Ericifolin, a member of the family of polyphenols, the richest source of antioxidants in the diet, can actually prevent prostate cancer from developing altogether.

With a US$1.5 million National Institutes of Health grant, they are currently exploring Ericifolin's anticancer activities - and its translational potential as a cancer chemopreventive agent for humans - in mice that have been genetically programmed to naturally develop prostate cancer at a certain age.

They also hope to begin a clinical trial in the near future with UHealth patients who are under active surveillance for early-stage or slow-growing prostate cancer, which does not yet warrant treatment. Since allspice is not toxic, Lokeshwar reasons those patients would be ideal candidates to take Ericifolin as a daily dietary supplement.

A biologist who began exploring the feasibility of natural anticancer agents about seven years ago, Lokeshwar turned his sights on allspice at the suggestion of a former research associate, Dominic A. Lyn. A co-author on the study, Lyn happened to be from Jamaica, the world's number-one exporter of allspice, which is the dried, unripe berry of Pimenta dioica, an evergreen tree native to Jamaica.

"He said, 'Let's try allspice. It's from Jamaica, and it's unique,'" Lokeshwar recalled.

"Not only is allspice a popular folk medicine remedy for a number of maladies, but 'pound for pound' it has the highest amount of antioxidants of any food we know."

rudimentary experiment

Their interest would escalate when they performed some rudimentary experiments with a jar of allspice powder Lyn borrowed from his wife's kitchen. Turning the powder into a water extract, they applied it to cancer cells and found it inhibited their growth. More elaborate and sophisticated experiments with allspice purified and liquefied in the Lokeshwar lab would produce the same results, first in cells, then in mice.

In an intriguing footnote, Zhang, a student in the Sheila and David Fuente Graduate Program in Cancer Biology, has since demonstrated that their aqueous allspice extract also impedes the growth of breast cancer cells, but with a different polyphenol, not Ericifolin. They are not sure yet which one but, in Lokeshwar's mind, that discovery raises the possibility that allspice may have many anticancer properties worth exploring.

In addition to Lokeshwar, Nagarajarao, Lyn and Zhang, other co-authors of the study, Ericifolin: a novel antitumor compound from allspice that silences androgen receptor in prostate cancer, are Khaled A. Shaaban, PhD, and Jurgen Rohr, PhD, of the University of Kentucky, and Susana Villate, a former research associate in the Department of Urology.

- Miller School of Medicine, University of Miami, Florida, United States