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suggesting that the carboxyl functional group in oleic acid also
could play a crucial role in the PEP inhibition. Anandamide
also showed no PEP inhibitory activity (Figure 1B), further
indication that carboxyl functional group in arachidonic acid
could be critical in the PEP inhibition. Our previous report on
two ginkgolic acids from Ginkgo biloba also suggested that
carboxyl functional group is important in the PEP inhibition
(19). These results suggest that not only the position of the
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unsaturated fatty acids is responsible for PEP inhibition.
Although IC50 values of oleic, linoleic, and arachidonic acids,
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Received for review October 11, 2005. Accepted December 30, 2005.
This work was supported by the SRC program of MOST/KOSEF (R11-
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