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Ultraviolet B (UVB) Photosensitivities of Tea Catechins and the Relevant Chemical Conversions.


ABSTRACT: Ultraviolet B (UVB) photosensitivities of eight catechins were screened. In both water and ethanol, epicatechin (EC, 575 ?M) and catechin (C, 575 ?M) 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 ?M) 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.

SUBMITTER: Shi M 

PROVIDER: S-EPMC6274363 | biostudies-literature | 2016 Oct

REPOSITORIES: biostudies-literature

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Ultraviolet B (UVB) Photosensitivities of Tea Catechins and the Relevant Chemical Conversions.

Shi Meng M   Nie Ying Y   Zheng Xin-Qiang XQ   Lu Jian-Liang JL   Liang Yue-Rong YR   Ye Jian-Hui JH  

Molecules (Basel, Switzerland) 20161010 10


Ultraviolet 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  ...[more]

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