Microbial Transformation of Azorellane and Mulinane Diterpenoids

Microbial transformation is an alternate strategy to obtain novel derivatives from natural products using whole cells or enzymes because of their capability to introduce functional groups in chemically inactive carbon positions. In this investigation, the microbial transformation of two diterpenoids, azorellanol and 13α-mulin-11-en-20-oic acid, in three fungal cultures ( Aspergillus alliaceus UI 315, Mucor circinelloides ATCC 7941, and Penicillium notatum ATCC 36740) and one bacterium ( Nocardia iowensis NRRL 5646) was explored. The results showed that while biomodification of azorellanol by N . iowensis produced the known diterpenoid 7-deacetyl-azorellanol, P . notatum produced two new derivatives identified as 4,16-dihydroxy-azorellanol and 2β,16-dyhydroxy-14-en-azorellanol. Similarly, microbial transformation of 13α-mulin-11-en-20-oic acid by P . notatum produced the known derivative 13β,14β-dihydroxy-mulin-11-en-20-oic acid and the novel product 13α,14β,16-trihydroxy-mulin-11-en-20-oic acid. Graphical Abstract