Photostability of biliverdin bound to smectite, clay mineral

Abstract Biliverdin, the precursor of bilirubin, was adsorbed onto the synthetic clay mineral, smectite, in a mixed solution of benzene and methyl alcohol (7:3 v/v) to form a biliverdin–smectite conjugate. The adsorption of biliverdin to smectite followed the Freundlich equation with an adsorption coefficient of 1.0. The water-soluble conjugate had a green color with the absorbance maxima at 679 and 378 nm. The biliverdin–smectite conjugate became photostable in water to irradiation with UV, although the biliverdin in benzyl alcohol was rapidly decolorized.