Ellagitannins of Davidia involucrata . I. Structure of Davicratinic Acid A and Effects of Davidia Tannins on Drug-Resistant Bacteria and Human Oral Squamous Cell Carcinomas

摘要

We isolated a new ellagitannin, davicratinic acid A ( 5 ), together with four known ellagitannins, davidiin ( 1 ), granatin A ( 2 ), pedunculagin ( 3 ), and 3- O -galloylgranatin A ( 4 ), from an aqueous acetone extract of dried Davidia involucrata leaves. The known ellagitannins were identified based on spectroscopic data. The structure of davicratinic acid A ( 5 ), a monomeric ellagitannin possessing a unique, skew-boat glucopyranose core, was established based on spectroscopic data. Additionally, we examined the effects of several tannins with good yields from this plant on drug-resistant bacteria and human oral squamous cell carcinomas, and found that davidiin ( 1 ) exhibited the most potent antibacterial and antitumor properties among the tannins examined.