Structure of acid-stable carmine.
Acid-stable carmine has recently been distributed in the U.S. market because of its good acid stability, but it is not permitted in Japan. We analyzed and determined the structure of the major pigment in acid-stable carmine, in order to establish an analytical method for it. Carminic acid was transformed into a different type of pigment, named acid-stable carmine, through amination when heated in ammonia solution. The features of the structure were clarified using a model compound, purpurin, in which the orientation of hydroxyl groups on the A ring of the anthraquinone skeleton is the same as that of carminic acid. By spectroscopic means and the synthesis of acid-stable carmine and purpurin derivatives, the structure of the major pigment in acid-stable carmine was established as 4-aminocarminic acid, a novel compound.
Sugimoto
Naoki
N
National Institute of Health Sciences: 1-18-1, Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan.
Kawasaki
Yoko
Y
Sato
Kyoko
K
Aoki
Hiromitsu
H
Ichi
Takahito
T
Koda
Takatoshi
T
Yamazaki
Takeshi
T
Maitani
Tamio
T
D000143:Acids; D000880:Anthraquinones; D002329:Carmine / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D004355:Drug Stability; D005505:Food Coloring Agents / Q000737:chemistry*; D037102:Lectins / Q000737:chemistry; D008745:Methylation; D013057:Spectrum Analysis
D000143:Acids; D000880:Anthraquinones; D005505:Food Coloring Agents; D037102:Lectins; D002329:Carmine; C511975:purpurin anthraquinone