Stereoselective biotransformation of timosaponin A-III by Saccharomyces cerevisiae

Yong Mei Hu, Zhiling YU, David W F FONG*

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

12 Citations (Scopus)


Bioconversion of timosaponin A-III (TA-III), one of the major steroidal saponins isolated from the rhizomes of Anemarrhenae asphodeloides Bunge (Liliaceae), was investigated in Saccharomyces cerevisiae. Five bioconversion products, denoted compounds 2-6, were obtained. Biotransformation metabolite 2 was a stereoisomer of TAIII with a specific isotype F-ring and ß-ranged CH3-21, which rarely occurs in nature. The structure of 2 was elucidated by extensive spectroscopic analysis (H-H COSY, HSQC, HMBC), as well as by high-resolution mass spectral analysis. The growth inhibitory activity of compounds 1-6 was assayed against four human cancer cell lines, HepG2, H-1299, HT-29, and HCT-116. Compounds 1 and 2 obviously inhibited the growth of the four types of cancer cells with IC50 values being less than 19 μM. A structure-activity relationship is discussed, and the spirostane-ring F in compounds 1 and 2 appears to be the critical bioactive moiety for the cell growth inhibitory property.

Original languageEnglish
Pages (from-to)582-589
Number of pages8
JournalJournal of Microbiology and Biotechnology
Issue number6
Publication statusPublished - Jun 2011

Scopus Subject Areas

  • Biotechnology
  • Applied Microbiology and Biotechnology

User-Defined Keywords

  • Biotransformation
  • Growth inhibitory effect
  • Saccharomyces cerevisiae
  • Steroidal saponins
  • Timosaponin A-III


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