Photo-Isomerization of the Nasunin, the Major Eggplant Anthocyanins

Abstract

It was reported that the acyl moieties of acylated anthocyanins with hydroxycinnamic acids were photo-isomerized from the trans- to the cis-isomer by light irradiation. We studied the effects of light irradiation on nasunin, p-coumaroylated anthocyanin from eggplant, and characterized the photo-isomerized anthocyanin by high performance liquid chromatography and fast atom bombardment mass spectroscopy. The photo-isomerization occurred under acidic conditions and was repressed with α-glucosylrutin that strongly absorbed ultraviolet light.