| 摘要 |
Incubations with Nocardia sp., NRRL 5646 were conducted to produce new derivatives of the abietane-diterpene chemoprotectant and antioxidant, carnosic acid. Reduction of the C-20 carboxylic acid functional group followed by methylation at the C-12 phenol afforded the novel compound 11,20-dihydroxy-12-methoxy-abiet-8,11,13-triene. Oxidative cyclization of carnosic acid to carnosol followed by dihydroxylation at the isopropyl moiety afforded the novel compound 11,12,16,17-tetrahydroxy-7-10-(epoxymethano)-abiet-8,11,13-triene-20-one. The metabolites are new carnosic acid derivatives whose structures were confirmed by mass spectrometry and NMR spectroscopic analysis. The radical quenching properties of the new metabolites using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free-radical scavenging assay showed activities improved over that of mixed tocopherols and carnosic acid. |
