SYNTHESIS OF CHEMICAL-BIOLOGY TOOLS ENABLING IN VIVO IMAGING AND ANALYSIS OF EPIGALLOCATECHIN GALLATE

(-)-Epigallocatechin gallate (EGCg) has multiple bioactivities, and imaging/analytical tools are required for drug development studies. Here we present full details of our synthetic studies aimed at providing building blocks for development of such tools, including a concise synthesis of model compound 5,7-dideoxyEGCg (DOEGCg, 2) and an asymmetric synthesis of 6-(5-aminopenty1)-5,7-deoxyepigallocatechin gallate (APDOEGCg, 4), which contains a reactive terminal amino group. To demonstrate its utility, APDOEGCg (4) was efficiently converted to a fluorescent probe 53 by linking it to a fluorescein derivative, Tokyo Green, via the amino group. We confirmed that 53 is suitable for in vivo imaging studies. We also prepared an immunogen 56 by conjugation of 4 to human serum albumin carrier protein via a glutaraldehyde linker, and we used 56 to raise anti-EGCg antiserum in mice. The fluorescent probe and antiserum should be useful tools for biochemical investigations of the localization and target sites of EGCg. APDOEGCg should also be available for developing other novel tools for biochemical studies of catechins.