Primary reaction intermediates of Type-I photosensitized lipid oxidation as revealed by time-resolved optical spectroscopies
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Primary reaction intermediates of Type-I photosensitized lipid oxidation as revealed by time-resolved optical spectroscopies. / Zhou, Yi-Ming; Zhang, Yan; Gao, Rong-Yao; Liu, Wei; Wei, Yuan; Han, Rui-Min; Wang, Peng; Zhang, Jian-Ping; Skibsted, Leif H.
In: Journal of Photochemistry and Photobiology A: Chemistry, Vol. 418, 113376, 2021.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Primary reaction intermediates of Type-I photosensitized lipid oxidation as revealed by time-resolved optical spectroscopies
AU - Zhou, Yi-Ming
AU - Zhang, Yan
AU - Gao, Rong-Yao
AU - Liu, Wei
AU - Wei, Yuan
AU - Han, Rui-Min
AU - Wang, Peng
AU - Zhang, Jian-Ping
AU - Skibsted, Leif H.
N1 - Funding Information: This work has been supported by the Natural Science Foundation of China (No. 21673288 ). Publisher Copyright: © 2021 Elsevier B.V.
PY - 2021
Y1 - 2021
N2 - Chlorophyll a (Chl a) as a lipophilic photosensitizer can induce biomembrane destruction via Type-II reaction involving singlet oxygen (1O2) as a primary initiator. Type-I oxidation by an excited-state photosensitizer reacting directly with lipid substrate also contributes but the primary intermediate remains to be verified experimentally. We have investigated the reaction dynamics initiated by Chl a-photosensitization involving oxygen and the -C=C- moieties of lipids in the membranes of small unilamellar vesicles (SUVs) prepared from phospholipids of different degree of unsaturation (0, 1 or 2). Under anaerobic condition, femtosecond time resolved absorption (fs-TA) combined with spectroelectrochemical spectroscopies validated the formation of Chl a[rad]− in subpicoseconds, and time resolved fluorescence spectroscopy revealed the rapid quenching of 1Chl a* with a rate constant of (28 ns)−1. These ultrafast processes, independent of oxygen, are ascribed to the electron transfer reaction from a -C=C- moiety to 1Chl a* as an initiation step of Type-I reaction. On longer timescales, ns-TA spectroscopy unraveled the drastic quenching of 3Chl a* by either -C=C- or O2, and the quenching by O2 was found to be 20 times more efficient. This together with the 1O2-luminesence analysis prove the involvement of both types of photosensitization. In addition, HPLC-MS spectroscopy confirmed the ketonic, the alcoholic and the core-aldehyde products of lipid oxidation. Moreover, the oxygen dependent partition between Type-I and Type-II reactions is discussed on a detailed kinetics basis, showing that the two mechanisms of lipid oxidation are equally important under an oxygen concentration of 1.3×10−5 M at room temperature.
AB - Chlorophyll a (Chl a) as a lipophilic photosensitizer can induce biomembrane destruction via Type-II reaction involving singlet oxygen (1O2) as a primary initiator. Type-I oxidation by an excited-state photosensitizer reacting directly with lipid substrate also contributes but the primary intermediate remains to be verified experimentally. We have investigated the reaction dynamics initiated by Chl a-photosensitization involving oxygen and the -C=C- moieties of lipids in the membranes of small unilamellar vesicles (SUVs) prepared from phospholipids of different degree of unsaturation (0, 1 or 2). Under anaerobic condition, femtosecond time resolved absorption (fs-TA) combined with spectroelectrochemical spectroscopies validated the formation of Chl a[rad]− in subpicoseconds, and time resolved fluorescence spectroscopy revealed the rapid quenching of 1Chl a* with a rate constant of (28 ns)−1. These ultrafast processes, independent of oxygen, are ascribed to the electron transfer reaction from a -C=C- moiety to 1Chl a* as an initiation step of Type-I reaction. On longer timescales, ns-TA spectroscopy unraveled the drastic quenching of 3Chl a* by either -C=C- or O2, and the quenching by O2 was found to be 20 times more efficient. This together with the 1O2-luminesence analysis prove the involvement of both types of photosensitization. In addition, HPLC-MS spectroscopy confirmed the ketonic, the alcoholic and the core-aldehyde products of lipid oxidation. Moreover, the oxygen dependent partition between Type-I and Type-II reactions is discussed on a detailed kinetics basis, showing that the two mechanisms of lipid oxidation are equally important under an oxygen concentration of 1.3×10−5 M at room temperature.
KW - Chlorophyll a
KW - Lipid oxidation
KW - Photosensitization
KW - Small unilamellar vesicle
KW - Time resolved spectroscopy
U2 - 10.1016/j.jphotochem.2021.113376
DO - 10.1016/j.jphotochem.2021.113376
M3 - Journal article
AN - SCOPUS:85106507436
VL - 418
JO - Journal of Photochemistry and Photobiology, A: Chemistry
JF - Journal of Photochemistry and Photobiology, A: Chemistry
SN - 1010-6030
M1 - 113376
ER -
ID: 273538933