7a-Hydroxyfrullanolide

An example of a simple biotransformation of a small natural product is shown in Fig. 14, m which the sesquiterpene lactone, 7a-hydroxyfrullanolide from the plant Sphaeranthus indicus was acetylated and reduced by two different Aspergillus species to give the two products shown (30). 

FIGURE 20.67 Biotransformation of C4-epimer (221) of 214, 7a-hydroxyfrullanolide (223), and frullano-lide (226) hy Aspergillus niger and Aspergillus quardilatus. 

Atta-ur-Rahman, M.I. Choudhary, A. Ata et al., 1994. Microbial transformation of 7a-hydroxyfrullanolide. 

A related sesquiterpene lactone, 7a-hydroxyfrullanolide (94), abundantly present in Sphaerantus indicus L. (Compositae), and which was demonstrated to have in vitro cytotoxic and antitumor activity, was used for microbial transformation in order to convert it to potentially more useftil metabolites. From nine fungi screened, two Aspergillus strains were found to reduce or acylate the side chain double bond [126], but no hydroxylation reaction was reported. 

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