Molecular Structure of Gardenia Blue Pigments by Reaction of Genipin with Benzylamine and Amino Acids

• DOI: 10.1021/acs.jafc.0c07948
• Publication Date: 2021-03-24T23:04:54Z
• Authors: 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
• Keywords: Genipin; Benzylamine; Heteronuclear molecule; Fast atom bombardment; Proton NMR

Genipin was reacted with benzylamine and several amino acids to prepare gardenia blue (GB). The time-course of GB formation monitored by high-performance liquid chromatography (HPLC), time-of-flight mass spectrometry (LC-TOFMS), 1H 13C NMR measurements. In this experiment, we determined the molecular structures some intermediates using accurate masses additional techniques such as heteronuclear multiple bond correlation (HMBC). GBs (GB-AAs) were characterized both solid-state Interestingly, many significant peaks appeared in spectra, although spectra from solution samples did not show any distinct peaks. Therefore, that GB-AAs had an alternating copolymer structure composed methyne 5H-2-pyrindine, which substituted at N atom linked 5 7 positions. To confirm structure, pyrolysis gas chromatography-mass (GC-MS) measurement carried out, 5H-2-pyrindine its methyl derivatives formed main products polymer chains.