Detection of
Vitamin C-induced Singlet Oxygen Formation in Oxidized LDL Using MCLA as A
Chemiluminescence Probe
WANG Juan, XING Da*
( Institute of Laser Life Science, South China Normal University, Guangzhou 510631, China )
Abstract In this study, it was observed that addition of
vitamin C (vit C) to oxidized low-density lipoprotein (Ox-LDL) by cupric ions
(Cu2+) could result in the formation of singlet oxygen (1O2). In experiments, 1O2 was detected
by chemiluminescence method using a Cypridina luciferin analog, 2-methyl-6(p-methoxyphenyl)-3,
7-dihydroimidazo［1, 2-a］pyrazin-3-one (MCLA), as a selective and sensitive
chemiluminescence probe.
Additional experimental evidence for the formation of 1O2
came from the quenching effect of sodium azide (NaN3) on vit
C-induced chemiluminescence in the reaction mixture of LDL-Cu2+-MCLA. Analysis based on the experimental
results demonstrated the plausible reaction mechanism is that vit C first
converts Cu2+ to its reduced state and vit C becomes vit C radical
itself, thereby stimulating the formation of peroxyl and alkoxyl radicals, and bimolecular reaction of peroxyl
radicals results in 1O2 production in the systems
studied.
Key words vitamin C; singlet oxygen;
MCLA; low-density
lipoprotein; Cu2+
*Corresponding author: Tel,
86-20-85210089; Fax, 86-20-85216052;
e-mail, [email protected]