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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Revisiting the Mechanism of Hydrolysis of Betanin

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Esteves, Larissa C. [1] ; Pinheiro, Amanda C. [1] ; Pioli, Renan M. [1] ; Penna, Tatiana C. [1] ; Baader, Wilhelm J. [1] ; Correra, Thiago C. [1] ; Bastos, Erick L. [1]
Total Authors: 7
[1] Univ Sao Paulo, Inst Quim, Dept Quim Fundamental, Sao Paulo, SP - Brazil
Total Affiliations: 1
Document type: Journal article
Source: Photochemistry and Photobiology; v. 94, n. 5, p. 853-864, SEP-OCT 2018.
Web of Science Citations: 3

Betanin (betanidin 5-O-beta-D-glucoside) is a water-soluble plant pigment used as a color additive in food, drugs and cosmetic products. Despite its sensitivity to light and heat, betanin maintains appreciable tinctorial strength in low acidic and neutral conditions, where the color of other plant pigments, such as anthocyanins, quickly fades. However, betanin is an iminium natural product that experiences acid- and base-catalyzed hydrolysis to form the fairly stable betalamic acid and cyclo-DOPA-5-O-beta-D-glucoside. Here, we show that the decomposition of betanin in aqueous phosphate solution pH 2-11 is subject to general base catalysis by hydrogen phosphate ion and intramolecular general acid and base catalysis, providing new insights on the mechanism of betanin hydrolysis. UV/Vis absorption spectrophotometry, H-1 NMR spectroscopy and mass spectrometry were used to investigate product formation. Furthermore, theoretical calculations support the hypothesis that the nitrogen atom of the tetrahydropyridine ring of betanin is doubly protonated, as observed for structurally simpler amino dicarboxylic acids. Our results contribute to the study of betanin and other pigments belonging to the class of betalains and to deepen the knowledge on the chemical properties of imino acids as well as on iminium-catalyzed modifications of carbonyl compounds in water. (AU)

FAPESP's process: 14/22136-4 - Use of green solvents and their mixtures for optimizing chemical processes
Grantee:Omar Abou El Seoud
Support type: Research Projects - Thematic Grants
FAPESP's process: 16/21445-9 - Betalains: structure-property relationships
Grantee:Erick Leite Bastos
Support type: Regular Research Grants
FAPESP's process: 15/08539-1 - Multi-User Equipment approved in grant 2014/15962-5: ion trap mass spectrometer modified to perform infrared vibrational spectroscopy (IRMPD)
Grantee:Thiago Carita Correra
Support type: Multi-user Equipment Program
FAPESP's process: 15/18474-4 - Functionalization of polysaccharides with photoresponsive betalains
Grantee:Amanda Capistrano Pinheiro
Support type: Scholarships in Brazil - Doctorate (Direct)
FAPESP's process: 14/15962-5 - Reaction mechanism of asymmetric catalysts by mass spectrometry and gas-phase vibrational ion spectroscopy
Grantee:Thiago Carita Correra
Support type: Research Grants - Young Investigators Grants