Ultraviolet B (UVB) Photosensitivities of Tea Catechins and the Relevant Chemical Conversions
AbstractUltraviolet B (UVB) photosensitivities of eight catechins were screened. In both water and ethanol, epicatechin (EC, 575 μM) and catechin (C, 575 μM) exhibited low photostabilities under 6 h UVB radiation with the generation of yellow photoproducts, while other catechins (epigallocatechin gallate, epigallocatechin, epicatechin gallate, gallocatechingallate, gallocatechin, catechin gallate) were relatively UVB-insensitive. Photoisomerization and photolysis were two important UVB-induced reactions to EC whereas photolysis was the dominant reaction for C. The influencing factors of time (2–10 h), solvent (water, ethanol) and substrate concentration (71.875–1150 μM) on UVB-induced chemical conversions of EC and C were investigated, and eight photoproducts were identified through ultra performance liquid chromatography-diode array detection-tandem mass spectrometry (UPLC-DAD-MS/MS) and 1H nuclear magnetic resonance (1H-NMR analysis). Photolysis reaction involved two pathways, including radical reaction and photo-induced electron transfer reaction. The 2,2-diphenylpicrylhydrazyl (DPPH) scavenging abilities of eight catechins did not change upon 6 h UVB irradiation. EC and C are photosensitive catechins among eight catechins causing deep color. View Full-Text
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Shi, M.; Nie, Y.; Zheng, X.-Q.; Lu, J.-L.; Liang, Y.-R.; Ye, J.-H. Ultraviolet B (UVB) Photosensitivities of Tea Catechins and the Relevant Chemical Conversions. Molecules 2016, 21, 1345.
Shi M, Nie Y, Zheng X-Q, Lu J-L, Liang Y-R, Ye J-H. Ultraviolet B (UVB) Photosensitivities of Tea Catechins and the Relevant Chemical Conversions. Molecules. 2016; 21(10):1345.Chicago/Turabian Style
Shi, Meng; Nie, Ying; Zheng, Xin-Qiang; Lu, Jian-Liang; Liang, Yue-Rong; Ye, Jian-Hui. 2016. "Ultraviolet B (UVB) Photosensitivities of Tea Catechins and the Relevant Chemical Conversions." Molecules 21, no. 10: 1345.
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