Sesquiterpenes microbial hydroxylation

Although much of the work on the microbial hydroxylation of amides has been directed at active-site m ing of the enzyme responsible, the products themselves are valuable building blocks for further synthesis, for example, for various optically active sesquiterpenes or p-lactams. In this latter context regioselective hydroxylation of unactivated positions is particularly attractive as several -lactam antibiotics, e.g. the carbapenem derivative thienamycin, have a free hydroxy group in their structure. 

Further information on microbial hydroxylation of sesquiterpenes is available. 

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. 

---