Broccoli Varieties Differ in Potential
Anticarcinogenic Activity By
January 2, 2001
In a ground-breaking study, Agricultural Research Service scientists
have screened broccoli varieties to see if they induce activity of a key enzyme
in mammals that may protect against certain cancers.
Agricultural Research Service plant geneticist Mark W. Farnham
U.S. Vegetable Laboratory in Charleston, S.C., worked with scientists in
the Brassica Chemoprotection Laboratory at
Universitys School of Medicine, Baltimore, Md. The scientists
evaluated a diverse collection of broccoli (Brassica oleracea) varieties
for their ability to stimulate whats called a mammalian detoxification
enzyme--which helps protect mammals against development of cancer.
In 1996 and 1997, Farnham grew 71 USDA broccoli varieties and five commercial
hybrids in the field, and then took extracts from each one. In these extracts,
the scientists looked for a chemoprotective compound called glucoraphanin. A
derivative of glucoraphanin spurs mammals to induce activity of detoxification
enzymes. The scientists found a 30-fold variation in glucoraphanin and the
activity of these enzymes among the broccoli tested. In the future, scientists
could use the enzyme activity to gauge a broccoli varietys anti-cancer
Data from several previously published studies have shown that
people who eat cruciferous vegetables like broccoli have a lower incidence of
colon and rectal cancers. Occurring in two out of 1,000 people, these account
for 15 percent of all cancer deaths.
Broccoli florets and young seedlings are rich sources of
glucoraphanin and its breakdown product, sulforaphane. Sulforaphane is a potent
inducer of mammalian detoxification enzyme activity and inhibits early tumor
growth in rodent models.
Scientists know little about variations of glucoraphanin and
sulforaphane in broccoli varieties. If genetic variation among varieties does
exist, then breeders could exploit it to develop new varieties with greater
levels of the protective compounds. And eating such improved broccoli might
stimulate an enhanced chemoprotective response against cancer.
ARS is the chief scientific research agency of the U.S.
Department of Agriculture.
Scientific contact: Mark Farnham,
U.S. Vegetable Laboratory, Charleston, S.C., phone (843) 556- 0840, fax
(843) 763-7013, email@example.com