A new antibacterial compound from Luo Han Kuo fruit extract (Siraitia grosvenori)

Abstract

Luo Han Kuo fruit (Siraitia grosvenori Swingle) has been used in China for centuries as a sweetening agent, and also used to treat sore throat and cough. In our recent study, a new bioactive compound, (2R,3S,4S)-2,3-trans-3,4-cis-5,3′-bimethoxy-7-(trans-2-propenal)-3,4-flavandiol (1), named siraitiflavandiol was obtained. The structure has been determined on the basis of spectroscopic studies including 1D and 2D NMR (¹H, ¹³C NMR, ¹H–¹H COSY, HSQC, HMBC, and NOESY), CD, EI-MS, and HR-EI-MS spectra. The new compound was evaluated in vitro for its inhibitory ability against the growth of oral bacterial species Streptococcus mutans, Porphyromonas gingivalis, and yeast Candida albicans. The minimum inhibitory concentrations were 6, 24, and 6 μg/ml, respectively.

Keywords:

• Siraitia grosvenori Swingle
• (2R,3S,4S)-2,3-trans-3,4-cis-5,3′-bimethoxy-7-(trans-2-propenal)-3,4-flavandiol
• Streptococcus mutans
• Porphyromonas gingivalis
• Candida albicans

Acknowledgements

We are grateful to the University of Kentucky Mass Spectrometry Facility for the mass spectra and the University of Kentucky Chemistry NMR Facility for the NMR spectral data. This work was supported by the grant R41DE17265-01 from the NIH/NIDCR.