Synthesis of cholesterol analogues bearing BODIPY fluorophores by Suzuki or Liebeskind-Srogl cross-coupling and evaluation of their potential for visualization of cholesterol pools.

We report a synthetic route to BODIPY-cholesterol conjugates in which the key steps were Suzuki or Liebeskind-Srogl cross-coupling of cholesterol phenyl moieties with structurally diverse BODIPY scaffolds. All conjugates feature single-bonded and hydrophobic linkages between the fluorophore and sterol that are devoid of heteroatoms. Using HeLa cells, we show that these BODIPY-cholesterol analogues can be used simultaneously with the parent BODIPY-cholesterol for cell imaging and flow cytometry. The BODIPY-cholesterol analogues exhibit similar cellular localization in HeLa cells and show similar cholesterol efflux properties from THP-1 cells to HDL acceptors. These results demonstrate that the red-shifted BODIPY-cholesterol analogues behave in a manner similar to unlabeled cholesterol and are useful probes for simultaneous visualization of intracellular cholesterol pools and for monitoring cholesterol efflux from cells to extracellular acceptors.