ISIS Report 29/04/05
Knotty but Nice: Spectacular Anti-Cancer Agents in Tree
Knots
Prof. Joe Cummins reports on
further anti-cancer chemicals that are found in common plant sources
A fully referenced version of
this article is posted on ISIS members’ website.
Details here
Two years ago I wrote on how organic agriculture has the potential to
combat cancer. Plant chemicals called phenolics or flavonoids, effective in
preventing cancer, have been found elevated in organic foods. Another family of
plant chemicals related to flavonoids, called lignans, recently yielded
spectacular results in preventing and treating human cancers.
Lignans contain two benzene rings to which are attached particular three
carbon arms. Lignans are not to be confused with lignin, the polymer that binds
cellulose fibers together to make cell walls. Lignin is synthesized from
monomer units similar to lignans, but lignin is not associated with the
beneficial properties of lignans.
A recent review suggested that an anti-cancer diet would decrease
breast, colorectal and prostate cancer by 60 to 70 percent and lung cancer by
40 to 50 percent. Taking flaxseed, especially its lignan fraction, lowers
cancer risk. Flaxseed lignan has been found effective not only in treating
cancer but also in reducing the risk of heart disease and to have beneficial
effects in lupus and polycystic kidney disease. Flaxseed meal ameliorated
kidney damage in type-two diabetes. The anticancer effect of a plant lignan was
demonstrated using human prostate cancer cells transplants in nude (immune
deficient) mice. Rat mammary tumors were reduced after treatment with a plant
lignan isolated from the knots of spruce trees. Along with flaxseed extracts
the knots of trees are proving to be a rich source of anti-cancer lignans.
The knots of spruce and fir trees are believed to be the richest source
of lignans. Up to 24 percent of the dry weight of the knot may be lignans,
while much lower levels are found in the stem wood. Extracting lignans from the
knots was not difficult.
Knot-wood extracts proved to be effective in controlling paper-mill
bacteria that undermine paper quality; and lignans were a deterrent to feeding
insects. These anti-microbial and insecticidal properties will no doubt be
further developed.
Not surprisingly, there has been a spate of patenting to exploit the
therapeutic potential of lignans. Of the many relevant patents, US Patent
6451849 deals with the use of a lignan for cancer prevention, and for treating
non-cancer hormone-dependent disease and cardiovascular disease. The patent
describes an active lignan and its preparation. US patent 67675654 describes a
method for preparing plant lignan for use in treating cancer, diabetes, lupus,
hypertension and high blood pressure. The first patent applications for
genetically modified crops with increased lignan content have begun to appear.
US patent application 20020174452 is for genetic modification of monocots such
as rice with genes that increase lignan level in grain using tissue specific
promoters.
It is not surprising that biotechnology has taken lignan to heart, and
that industry has a large and shameless public relations machinery which will
likely try to make it look as if biotechnology, and not nature, that has
invented lignans.
Like numerous other health-promoting natural chemicals, lignans are
common in plant species that are still widely available, although they are
increasingly threatened by industrial farming and especially GM crops, which
have now proved to be even more destructive of natural biodiversity than
conventional industrial farming ("GM crop fails final test", ISIS report). This
is another reason for a comprehensive shift to sustainable farming systems that
preserve and enhance natural biodiversity.
Support our Sustainable World global initiative:
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