MANHATTAN -- A Kansas State University
researcher is studying the potential health
benefits of a specially bred purple sweet potato
because its dominant purple color results in an
increased amount of anti-cancer components.
K-State's Soyoung Lim,
doctoral student in human nutrition, Manhattan,
is working with George Wang, associate professor
of human nutrition at K-State, to understand the
pigment effects of a Kansas-bred purple sweet
potato on cancer prevention.
Lim said purple sweet
potatoes have high contents of anthocyanin,
which is a pigment that presents the purple
color in the vegetable. The pigment can produce
red, blue and purple colors depending on the
source's chemical structure, such as in foods
like blueberries, red grapes and red cabbage.
She said anthocyanins have
been epidemiologically associated with a reduced
cancer risk, but the anti-cancer ability of the
purple sweet potato has not been well
investigated.
Lim used a sweet potato
with pronounced purple flesh and skin that was
developed by K-State's Ted Carey, professor of
horticulture, at K-State's John C. Pair
Horticultural Center in Haysville.
"Sometimes we can find
purple sweet potatoes in the grocery store, but
they don't have this purple color on the skin
and inside," Lim said.
Three different purple
sweet potatoes were used that had varying
amounts of anthocyanin for the project. To
quantify the amount in each potato, Lim
extracted pigments from the vegetables and
injected them into an HPLC-MS Analysis, which
she said is a method that separates components.
The potatoes were
segregated by multiple traits based on flesh
pigmentation and fiber contents. The analysis
determined that the Kansas-bred potato had
significantly higher anthocyanin contents
compared to the other potatoes. The analysis
also found two derivatives of anthocyanin that
were dominant: cyanidin and peonidin, Lim said.
Lim also measured the
potatoes' total phenolic content. Lim said
phenols are chemical compounds that have been
found to have anti-aging and antioxidant
components. The specially bred purple sweet
potato had a much higher total phenolic content
and antioxidant capacity than the other
regularly occurring purple sweet potatoes, she
said.
The K-State researchers
also wanted to see the specific effects of
cyanidin and peonidin. Lim treated human colon
cancer cells with low concentrations of the
pigment derivatives and also studied the effects
on the cell cycles.
Cyanidin and peonidin
showed significant cell growth inhibition for
the cancer cells, but there were no significant
changes in the cell cycle. Lim said a better
understanding of the underlying mechanisms in
the Kansas-bred potato could provide scientific
evidence of its health benefits.
Lim presented the research
at the Experimental Biology Meeting in New
Orleans in April. She is doing a follow-up study
this summer that will involve treating animal
cancer cells with the pigments.
Other contributors to the
project include Takeo Iwamoto, research
assistant professor of biochemistry at K-State;
and K-State students Genna Gehrt, Alma, and
Kacey Provenzano, Derby, both May 2009
bachelor's graduates in nutritional sciences.
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