Biotransformation of resibufogenin by Actinomucor elegans

Abstract

Resibufogenin (RB), a major bioactive bufadienolide, has the potential anticancer activity. In the present work, biotransformation of RB by Actinomucor elegans AS 3.2778 yielded five products, namely 3-oxo-resibufogenin (1), 3-epi-resibufogenin (2), 3-epi-12-oxo-hydroxylresibufogenin (3), 3α-acetoxy-15α-hydroxylbufalin (4), and 3-epi-12α-hydroxylresibufogenin (5), respectively. Among them, metabolites 3 and 4 are previously unreported. The chemical structures of metabolites 1–5 were fully elucidated on the basis of 2D NMR and HR-MS. The highly stereo- and regio-specific isomerization, hydroxylation, and esterification reactions were observed in the biotransformation process of RB by A. elegans. Their cytotoxicities against A549 and H1299 cells were evaluated.

Keywords::

• biotransformation
• Actinomucor elegans
• resibufogenin
• bufadienolides
• cytotoxicity

Acknowledgment

The authors thank National Natural Science Foundation of China (81202589 and 81303146), Funding Project of Competence Development Program for Beijing VET Teachers, and the Scientific Research Base Fund for Science and Technology Innovation, PHR (IHLB201107151) and Specialized Research Fund for the Doctoral Program of Higher Education of China (20132105130001) for financial support.

Notes

^1. These two authors contributed equally to this work.