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DOI: 10.1055/s-0028-1084807
Biotransformation of lupeol by Penicillium roqueforti
Microbial transformation has been used as a useful tool to enhance the structural diversity of natural triterpenes [1,2]. The great potential of fungi regarding to their aggressive growth, biomass production and extensive hyphal surface area make them an attractive approach to be explored for biotransformation. In this work, the biotransformation of lupeol was investigated by using submerged shaken liquid culture of Penicillium roqueforti. The fungus was cultivated in a rich pre-fermentative medium at 30°C and 120 rpm for 72 hours. The resulting mycelia were harvested and transferred to different fermentative media (Czapek and Koch's K1). Lupeol was added as solution in dimethylsulfoxide and the cultures were incubated at 30°C and 120 rpm for 10 days. Samples of each culture were taken every 24 hours, extracted with ethyl acetate, and analyzed by GC/MS. Experiments were also run with control flasks. The biotransformation of lupeol by P. roqueforti afforded a compound which showed the molecular ion peak at m/z 384, and it was detected only in the culture developed in the Koch's K1 medium for 7 days. The mass spectrum of this compound displayed a series of ions similar to those observed for lupeol that indicated that the main portion of the molecule has not been modified. However, the data obtained from mass spectrometry analysis suggest that this compound could be produced from lupeol as a result of successive oxidations in its isopropenyl side chain, followed by sucessive decarboxylations.
Acknowledgements: FAPESP.
References: 1. Zhang, J. et al. (2005) Tetrahedron Lett. 46: 2337–2340.
2. Bastos, D. Z. L. et al. (2007) Phytochemistry 68: 834–839.