Microbial transformation of nerylacetone by fungal strains

Acyclic terpenoids are widely distributed in nature and they are important biosynthetic precursors of many biologically active cyclic isoprenoids produced by higher plants. Microbial transformation of acyclic terpenoids could be a good way for synthesis of many new bioactive compounds with isoprenoid structure. Recently we have published the synthesis of oxyderivatives of farnesol by fungal strains [1]. Here we report the biotransformation of nerylacetone (1) by means of six strains of microorganisms, which were selected in the screening procedure. The substrate was transformed by Fusarium equiseti 15, Fusarium avenaceum 12, Fusarium oxysporum 13, Botrytis cinerea 235, Acremonium roseum 346 and Aspergillus niger MB (being the UV mutant) into two oxyderivatives of nerylacetone (2,3) and cis isomer of alkylsubstituted β- hydroxy-γ-lactone (4).

In the culture of F. avenaceum 12, B. cinerea 235, A. niger MB and F. equiseti 15 the regioselective and enantioselective oxidation of terminal double bond was observed. The final products of this oxidation, 9,10-dihydroxynerylacetone (2) or hydroxydiketone (3) were formed probably, like in case of geranylacetone [1], via 9,10-epoxynerylacetone. The most interesting conversion of nerylacetone (1) to β-hydroxy-γ-lactone (4) was observed in the case of biotransformation of the substrate with F. oxysporum and A. roseum. The (4S, 5S) isomer of 5-(4'-methyl-3'pentenyl)-4-hydroxy-5-methyldihydrofuran-2-one (4) was isolated as the only product. This β-hydroxy-γ-lactone, which was earlier isolated from Mutisia fresiana [2], showed antifungal activity [2,3] against Cladosporium cucumerinum.

References: 1. Gliszczyńska, A., Wawrzeńczyk, C. (2007)J. Mol. Catal. Enzyme:B (in press)

2. Viturro, C.I. et al. (2001) Tetrahedron: Asymmetry 12: 991–998

3. Kerrigan, N.J. et al. (2004) Tetrahedron Lett. 45: 9087–9090