Binding of crocetin to plasma albumin.

The binding of the carotenoid crocetin to human and bovine plasma albumin was studied using absorption and fluorescence techniques. Shifts in the absorption spectrum of crocetin, quenching of the albumin fluorescence, and competitive binding studies all provided information about the binding of crocetin to albumin. These studies suggest that crocetin binds to plasma albumin by occupying the free fatty acid binding sites. The binding constants for the first two binding sites are in the 10(5)-10(7) M-1 range and are an order of magnitude less than the values reported for other conjugated polyene fatty acids. The importance of this strong plasma albumin binding to the pharmacology of crocetin is discussed.