Cholesterol: Revisiting its fluorescent journey on 200th anniversary of Chevruel’s “cholesterine”

The legacy of Micheal Chevruel’s discovery of “cholesterine” as a non-saponifiable lipid from gall stones has ignited the imagination and research of countless minds for over two centuries now. In this review, we have provided a brief chronicle of the early history of cholesterol research which paved the way to present day understanding of membrane biology. We have discussed the properties and functionality of various fluorescent analogs of cholesterol in view of the ultra-high sensitivity, rapid response and spatial resolution obtained using fluorescence spectroscopic, microscopic and flow cytometric techniques. The repertoire of fluorescent analogs discussed for cholesterol research include the naturally occurring analogs (dehydroergosterol and cholestatrienol); polarity sensitive probes (NBDand dansyl-cholesterol); bright and photostable probe (BODIPY-cholesterol); clickable alkyne cholesterol and cholesterol binding macromolecules (fluorescently labeled non-toxic subunits of perfringolysin O and filipin) in monitoring cholesterol content in live and fixed cells. We have elaborated on the applications of the fluorescent analogs of cholesterol in clinical research, taking atherosclerosis, Niemann–Pick C and Alzheimer’s disease as representative examples. The applicability of fluorescent probes of cholesterol has become more relevant with the advent of various super-resolution microscopic techniques today and holds the promise of shedding light into the molecular orchestra of lipid-protein interaction with nanometer-scale resolution.