Kaname Tsutsumiuchi, Tomozou Toyoshima, Fumiya Hasegawa, Riku Terasawa, Wataru Honda, Minami Sakakibara, Yasuyuki Ishida, Yoshitomo Ikai, Ryo Ishibashi, Kota Furuya, Takashi Morimoto, Kyoko Ishizuki, Yuzo Nishizaki, Naoko Masumoto, Naoki Sugimoto, Kyoko Sato, Hisao Oka
Journal of agricultural and food chemistry 2021 Apr 07Genipin was reacted with benzylamine and several amino acids to prepare gardenia blue (GB). The time-course of GB formation with benzylamine was monitored by high-performance liquid chromatography (HPLC), liquid chromatography time-of-flight mass spectrometry (LC-TOFMS), and 1H and 13C NMR measurements. In this experiment, we determined the molecular structures of some intermediates using accurate masses and additional NMR techniques such as heteronuclear multiple bond correlation (HMBC). GBs with amino acids (GB-AAs) were characterized by both liquid and solid-state NMR measurements. Interestingly, many significant peaks appeared in the solid-state NMR spectra, although the 13C NMR spectra from solution samples did not show any distinct peaks. Therefore, we determined that GB-AAs had an alternating copolymer structure composed of methyne and 5H-2-pyrindine, which was substituted by amino acids at N atom and linked with methyne at 5 and 7 positions. To confirm this molecular structure, the pyrolysis gas chromatography-mass spectrometry (GC-MS) measurement of GB-AAs was carried out, and 5H-2-pyrindine and its methyl derivatives were formed as main pyrolysis products from the polymer chains.
Kaname Tsutsumiuchi, Tomozou Toyoshima, Fumiya Hasegawa, Riku Terasawa, Wataru Honda, Minami Sakakibara, Yasuyuki Ishida, Yoshitomo Ikai, Ryo Ishibashi, Kota Furuya, Takashi Morimoto, Kyoko Ishizuki, Yuzo Nishizaki, Naoko Masumoto, Naoki Sugimoto, Kyoko Sato, Hisao Oka. Molecular Structure of Gardenia Blue Pigments by Reaction of Genipin with Benzylamine and Amino Acids. Journal of agricultural and food chemistry. 2021 Apr 07;69(13):3904-3911
PMID: 33761247
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