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high-throughput bioassays, molecular biologist Jong Kim (left) and research
leader Bruce Campbell determine the effects gallic acid has on genes that
control aflatoxin production. Click the image for more information about
Tasty Nuts' Natural Defense: Caffeic Acid?
Wood October 10, 2006
Healthful nuts like almonds, pistachios and walnuts pass rigorous
tests before they make their way into your shopping cart. The tests ensure that
the nuts are free of unsafe levels of a natural, cancer-causing compound called
A fungus, or mold, known as Aspergillus flavus is a leading
source of the toxin. Now, Agricultural
Research Service scientists and their colleagues have discovered that
another natural compound, an antioxidant known as caffeic acid, may be
particularly adept at thwarting the mold's aflatoxin-making mechanisms.
That's according to
Campbell, who leads the agency's
Mycotoxin Research Unit, and postdoctoral molecular biologist
H. Kim. Both are based at the
Regional Research Center in Albany, Calif.
When the A. flavus mold feeds on certain kinds of tree nuts,
the nuts respond by forming compounds called "oxidants." The mold, now
undergoing what is known as "oxidative stress," reacts by producing
However, if the tree nuts' next move is to produce caffeic acid, for
instance, this antioxidant canas its name impliescounter the mold's
The result? Caffeic acid can quell nearly all of the mold's
aflatoxin production, Campbell and Kim found in their laboratory tests.
This research could lead to safe, Earth-friendly ways to put
antioxidants to work in tree nut orchards. For example, antioxidants could be
applied to trees, or perhaps the trees' own supply of antioxidants could be
bolstered through plant breeding.
The studies are the first to show that oxidative stress that would
otherwise trigger or enhance A. flavus aflatoxin production in tree nuts
can be stymied by caffeic acid.
article in the current issue of Agricultural Research magazine
describes the investigations.
ARS is the U.S. Department of
Agriculture's chief scientific research organization.