title: Oxidation, reduction, and methylation of carnosic acid by Nocardia.
abstract: 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.
mesh_terms: D045784:Abietanes; D000975:Antioxidants / Q000378:metabolism*; D001713:Biphenyl Compounds; D003500:Cyclization; D004224:Diterpenes / Q000737:chemistry / Q000494:pharmacology*; D016166:Free Radical Scavengers / Q000737:chemistry / Q000494:pharmacology*; D013058:Mass Spectrometry; D008745:Methylation; D015394:Molecular Structure; D009615:Nocardia / Q000378:metabolism*; D019906:Nuclear Magnetic Resonance, Biomolecular; D010084:Oxidation-Reduction; D010851:Picrates; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D027542:Rosmarinus / Q000737:chemistry*; D013329:Structure-Activity Relationship
chemical_list: D045784:Abietanes; D000975:Antioxidants; D001713:Biphenyl Compounds; D004224:Diterpenes; D016166:Free Radical Scavengers; D010851:Picrates; D010936:Plant Extracts; C004931:1,1-diphenyl-2-picrylhydrazyl; C018381:salvin