Effects of chemically defined tannins on poly (ADP-ribose) glycohydrolase activity. |
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| Authors: | Y J Tsai H Abe H Maruta T Hatano H Nishina H Sakagami T Okuda S Tanuma |
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| Institution: | Department of Pharmacology, Faculty of Medical Sciences, Taipei Medical College, Taiwan, R.O.C. |
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| Abstract: | Three classes of chemically defined tannins, gallotannins, ellagitannins and condensed tannins were examined for their inhibitory activities against purified poly (ADP-ribose) glycohydrolase. Ellagitannins showed higher inhibitory activities than gallotannins. In contrast, condensed tannins, which consist of an epicathechin gallate (ECG) oligomer without a glucose core were not appreciably inhibitory. Kinetic analysis revealed that the inhibition of ellagitannins was competitive with respect to the substrate poly(ADP-ribose), whereas gallotannins exhibited mixed-type inhibition. These results suggest that conjugation with glucose of hexahydroxy-diphenoyl (HHDP) group, which is a unique component of ellagitannins, potentiated the inhibitory activity, and that the structure of ellagitannins may have a functional domain which competes with poly(ADP-ribose) on the poly(ADP-ribose) glycohydrolase molecule. |
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