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.

We isolated a new ellagitannin, davicratinic acid A (), together with four known ellagitannins, davidiin (), granatin A (), pedunculagin (), and 3--galloylgranatin A (), from an aqueous acetone extract of dried leaves. The known ellagitannins were identified based on spectroscopic data. The structure of davicratinic acid A (), 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 () exhibited the most potent antibacterial and antitumor properties among the tannins examined.