Oxidation, reduction, and methylation of carnosic acid by Nocardia.
Preparative-scale incubations with Nocardia sp. NRRL 5646 were conducted to produce new derivatives of the abietane diterpene chemoprotectant and antioxidant carnosic acid (1). Reductive biotransformation of the C-20 carboxylic acid functional group followed by biological methylation at the C-11 phenol afforded 4. Oxidative cyclization of 1 to carnosol 5 followed by dihydroxylation at the isopropyl moiety afforded 6. Metabolites 4 and 6 are new carnosic acid derivatives whose structures were confirmed by mass spectrometry and NMR spectroscopic analysis. The radical quenching properties of 4-6 using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free-radical-scavenging assay showed activities similar to that of mixed tocopherols and carnosic acid.[1]References
- Oxidation, reduction, and methylation of carnosic acid by Nocardia. Hosny, M., Johnson, H.A., Ueltschy, A.K., Rosazza, J.P. J. Nat. Prod. (2002) [Pubmed]
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