Fluoindeneacids A and B: Antioxidant Cyclopentane-Containing Molecules with Enzyme-Triggered Nonenzymatic Skeletal Rearrangement

Abstract Fluoindeneacids A and B (5 and 6, respectively), featuring an unprecedented indene core linked to a 2,3-dihydroxybenzoyl moiety, were isolated from the FlsO1-catalyzed reaction of prejadomycin (1). Their structures were established by spectroscopic analysis and ECD calculations. Biochemical and isotopic labeling studies indicate their formation via an enzyme-triggered, nonenzymatic skeletal rearrangement of putative precursor 10. Both compounds exhibited potent in vitro antioxidant activity and cytoprotection against H2O2-induced damage.