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of b-amyrin, to the best of our knowledge, have not yet been described in the literature.
Interestingly, another type of microorganism that promoted triterpene rearrangement
was already described (Cheng et al., 2004; Zhang, Cheng, Yu, Cordell, & Qiu, 2005),
where an ursane-type triterpene was converted into an oleanane-type triterpene by a
species of Nocardia.
Biotransformations such as the present reaction accomplished by L. muscarinium
and those described by Cheng et al. (2004) and Zhang et al. (2005) constitute a neat
alternative choice for the synthesis of some key biologically active compounds
starting from less polar natural triterpenes, although, as for most fungal-performed
reactions described for the first time, yield improvement is still a challenge (Ye &
Guo, 2008).
Acknowledgements
The authors thank CNPq for scholarships (307846/2006-7 and 141551/2007-0) and
FAPEMIG (APQ-6629-5.02/07) and IFS (F/3564-2) for financial help.
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