New dihydrochalcone glycosides from Lithocarpus litseifolius and the phenomenon of C–H→C–D exchange observed in NMR spectra of phenolic components

Abstract

Two new dihydrochalcone glycosides named 6″-O-acetyltrilobatin (1) and 3″-O-acetylphloridzin (2) as well as four known compounds were isolated from the leaves of Lithocarpus litseifolius (Hance) Chun (family Fagaceae). Their structures were elucidated on the basis of spectroscopic analyses. The phenomena of C–H → C–D exchange were observed in NMR spectra of the isolated phenolic components when measured in deuterated methanol.

Keywords:

• Lithocarpus litseifolius
• Fagaceae
• dihydrochalcone glycoside
• C–H → C–D exchange

Acknowledgements

The authors are grateful to the financial support of Shanghai-Unilever Research and Development Fund (06SU07004). The authors also wish to thank Professors Ying Zhou and Ding Fang of Guangxi Institute of Chinese Traditional Medicine and Mr Jinchao Chen of Bama Longevity Insititute for supplying the plant material and valuable information and identification of the voucher specimen.