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15 E. Ueda, Y. Yoshikawa, Y. Ishino, H. Sakurai, and Y.
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high insulinomimetic activity, as evaluated in vitro, and
decreased the serum TG levels and HbA1c concentrations in
KK-Ay mice in vivo. Thus, Zn(gln-e)2 could be a useful anti-
diabetic material. Recently, theanine (gln-e) has been suggest-
ed to reduce fat tissue in rodents,33 and it is known that insulin
secretion has a close relation to obesity.34 Therefore, gln-e
may strengthen the antidiabetic action of Zn(II) complex.
In conclusion, we propose new candidates of insulino-
mimetic Zn(II) complexes with N-alkylated amides of gln. In
addition, the result of Zn(II) complexes with the compositions
of Japanese green tea shows not only a high insulinomimetic
activity in in-vitro experiments by the multiplication of zinc
and the ligand, but also the possibility to develop novel, clin-
ically useful and low toxic Zn(II) complexes from natural
products. In particular, we can expect the theanine/Zn com-
plex, Zn(gln-e)2, to be a highly antidiabetic material.
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20 E. Mindell, ‘‘Supplement Bible,’’ Simon & Schuster Inc.,
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The authors are grateful to the members of the analytical
center of Osaka City University for elemental analyses and
FAB MS.
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23 E. Ueda, Y. Yoshikawa, N. Kishimoto, M. Tadokoro,
H. Sakurai, N. Kajiwara, and Y. Kojima, Bull. Chem. Soc. Jpn.,
in press.
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