摘要
4-Hydroxycinnamic acid derivatives,including ferulic acid (FA) (1),sinapic acid (SA) (2) and caffeic acid (CA) (3),are widely distributed in the plant kingdom,and undergo oxidative cross-coupling leading to the corresponding dehydrodimers,trimers and even higher oligomers in plants. In order to evaluate the antioxidative ability of these 4-hydroxycinnamic acid derivatives and their oligomers,we synthesized 8-8'-bis-lactone-dimers (8-8'-DiFA (4),8-8'-DiSA (5) and 8-8'-DiCA (6)),as well as a new trimer (7),by the reaction of the corresponding monomers (1-3) with Ag2O in methanol,and assayed their free radical-scavenging activity by the reaction with 2,2-diphenyl-1-picrylhydrazyl radical (DPPH·). It was found that CA (3) and 8-8'-DiCA (6) bearing o-dihydroxyl groups exhibited significantly higher radical-scavenging activity than those bearing no such groups,and oxidative coupling of CA (3) resulted in remarkable enhancement in the activity.
4-Hydroxycinnamic acid derivatives, including ferulic acid （FA） （1）, sinapic acid （SA） （2） and caffeic acid （CA） （3）, are widely distributed in the plant kingdom, and undergo oxidative cross-coupling leading to the corresponding dehydrodimers, trimers and even higher oligomers in plants. In order to evaluate the antioxidative ability of these 4-hydroxycinnamic acid derivatives and their oligomers, we synthesized 8-8＇-bis-lactone-dimers （8-8＇-DiFA （4）, 8-8＇-DiSA （5） and 8-8＇-DiCA （6））, as well as a new trimer （7）, by the reaction of the corresponding monomers （1-3） with Ag20 in methanol, and assayed their free radical-scavenging activ- ity by the reaction with 2,2-diphenyl-l-picrylhydrazyl radical （DPPH-）. It was found that CA （3） and 8-8＇-DiCA （6） bearing o-dihydroxyl groups exhibited significantly higher radical-scavenging activity than those bearing no such groups, and oxidative coupling of CA （3） resulted in remarkable enhancement in the activity.
基金
supported by the National Natural Science Foundation of China (20972063 and 20621091)
the 111 Project
Program for New Century Excellent Talents in University (NCET-06-0906)
关键词
氧化偶联
衍生物
肉桂酸
自由基清除
DPPH自由基
抗氧化能力
羟基酸
低聚物
hydroxycinnamic acid derivatives, dehydrodimers, trimers, silver oxide, antioxidant, 2,2-diphenyl-l-picryihydrazyl radi-cal, structure-activity relationship
