Natural substances in orange, tangerine inhibit cancer

March 20, 2000

Effective against prostate cancer, lung cancer and melanoma

SAN FRANCISCO, March 30 -- Naturally occurring substances in citrus juices, called flavonoids, show promise against prostate cancer, lung cancer and melanoma in laboratory studies, according to a joint Canadian-United States study. The findings were presented here today at the 219th national meeting of the American Chemical Society, the world's largest scientific society. The weeklong meeting is expected to draw nearly 20,000 attendees from around the world.

Twenty-two flavonoids were examined during the study; this is the first time they have been tested against melanoma and prostate and lung cancer, says one of the lead researchers, Najla Guthrie, Ph.D., president of KGK Synergize, Inc., a research and development company in London, Ontario, Canada. The research was conducted in collaboration with the U.S. Department of Agriculture (USDA).

Orange and tangerine juice, in particular, produced "very encouraging results," according to Guthrie.

Of the 22 flavonoids studied, two that occur naturally in tangerine juice -- tangeretin and nobiletin -- "were the most effective inhibitors of human prostate cancer cells," according to Guthrie and colleague John Manthey, Ph.D., of the USDA's Agricultural Research Station in Winter Haven, Fla. The compounds also inhibited the growth of melanoma cells, notes Guthrie. Her lab previously reported that the tangerine compounds were effective against breast cancer cells.

A flavonoid found in both tangerines and oranges, 5-desmethyl sinensetin, inhibited human lung cancer cells most effectively, according to Guthrie.

In comparison with other compounds the researchers have studied, the tangerine and orange flavonoids are "very effective." Small amounts inhibit proliferation of cancer cells, according to Guthrie.

A synthetic flavonoid, quercetrin tetramethyl ether, also inhibited the growth of colon cancer cells during the studies, says Guthrie. The synthetic flavonoid was made by modifying quercetrin extracts. Quercetrin is found in many plants other than citrus, notes Guthrie.

"We looked at 22 flavonoids -- some naturally occurring, some synthetic -- and these are the most effective out of them," Guthrie points out. Some of the citrus compounds being studied are inhibiting the cells in the same concentration range as the breast cancer drug tamoxifen, she adds.

"The next step is to look at them in animals." Among the questions still to be answered, she said, are: "How are they metabolized? Do they get to the cells? Do they have the same effect?"

Animal studies have begun, says Guthrie, but it is too early to report preliminary data. She expects some results within about a year.

Dr. Guthrie is President, KGK Synergize, Inc. in London, Ontario, Canada.

Dr. Manthey is Research Chemist, U.S. Citrus and Subtropical Products Research Laboratory, U.S. Department of Agriculture, Agricultural Research Service, Winter Haven, Fla.

Dr. Guthrie will present her paper, AGFD 183, on Thursday, March 30, at 10:50 a.m., at the Moscone Convention Center, Room 124, Exhibit Level.
-end-
A nonprofit organization with a membership of 161,000 chemists and chemical engineers, the American Chemical Society www.acs.org publishes scientific journals and databases, convenes major research conferences, and provides educational, science policy and career programs in chemistry. Its main offices are in Washington, D.C., and Columbus, Ohio.

American Chemical Society

Related Prostate Cancer Articles from Brightsurf:

Low risk of cancer spread on active surveillance for early prostate cancer
Men undergoing active surveillance for prostate cancer have very low rates - one percent or less - of cancer spread (metastases) or death from prostate cancer, according to a recent study published in the Journal of Urology®, an Official Journal of the American Urological Association (AUA).

ESMO 2020: Breast cancer drug set to transform prostate cancer treatment
A drug used to treat breast and ovarian cancer can extend the lives of some men with prostate cancer and should become a new standard treatment for the disease, concludes a major trial which is set to change clinical practice.

Major trial shows breast cancer drug can hit prostate cancer Achilles heel
A drug already licensed for the treatment of breast and ovarian cancers is more effective than targeted hormone therapy at keeping cancer in check in some men with advanced prostate cancer, a major clinical trial reports.

The Lancet: Prostate cancer study finds molecular imaging could transform management of patients with aggressive cancer
Results from a randomised controlled trial involving 300 prostate cancer patients find that a molecular imaging technique is more accurate than conventional medical imaging and recommends the scans be introduced into routine clinical practice.

Common genetic defect in prostate cancer inspires path to new anti-cancer drugs
Researchers found that, in prostate cancer, a mutation leading to the loss of one allele of a tumor suppressor gene known as PPP2R2A is enough to worsen a tumor caused by other mutations.

First prostate cancer therapy to target genes delays cancer progression
For the first time, prostate cancer has been treated based on the genetic makeup of the cancer, resulting in delayed disease progression, delayed time to pain progression, and potentially extending lives in patients with advanced, metastatic prostate cancer, reports a large phase 3 trial.

Men taking medications for enlarged prostate face delays in prostate cancer diagnosis
University of California San Diego School of Medicine researchers report that men treated with medications for benign prostatic hyperplasia (enlarged prostate) experienced a two-year delay in diagnosis of their prostate cancer and were twice as likely to have advanced disease upon diagnosis.

CNIO researchers confirm links between aggressive prostate cancer and hereditary breast cancer
The study has potential implications for families with members suffering from these types of tumours who are at an increased risk of developing cancer.

Distinguishing fatal prostate cancer from 'manageable' cancer now possible
Scientists at the University of York have found a way of distinguishing between fatal prostate cancer and manageable cancer, which could reduce unnecessary surgeries and radiotherapy.

Researchers find prostate cancer drug byproduct can fuel cancer cells
A genetic anomaly in certain men with prostate cancer may impact their response to common drugs used to treat the disease, according to new research at Cleveland Clinic.

Read More: Prostate Cancer News and Prostate Cancer Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.