5-cholesten-3-ol 6-[(7-nitro-2-1,3-benzoxadiazol-4-yl)aMino]caproate

3-hexanoyl-NBD Cholesterol is a fluorescently-tagged cholesterol derivative with hydrophilic NBD fluorophore attached to carbon 3, at the hydrophilic end of cholesterol, separated by a 6-carbon spacer. This allows the cholesterol to orient in membrane bilayers while the fluorescent tag is presented outside the bilayer. This should model the behavior of cholesterol in membranes better than the previously-used 25-NBD cholesterol, which positions NBD directly on the 25th carbon of cholesterol at the hydrophobic terminus. Fluorescently-tagged lipids are used to study their interactions with proteins, their utilization by cells, and liposomes, and for the development of assays for lipid metabolism.

Cholesterol is produced from acetyl-CoA by a complex multistep mevalonate pathway. In mammals, liver is the main site of de novo cholesterol synthesis contributing to almost 80% of total cholesterol synthesis. Cholesterol and its metabolites, along with its precursors, play important roles in cellular membrane physiology. They also have roles in reproductive biology, dietary nutrient absorption, stress responses, salt and water balance and calcium metabolism.