Shi Gaosheng, Kim Hyein, Koo Sangho
Department of Energy Science and Technology, Myongji University, Myongji-Ro 116, Yongin 17058, Gyeonggi-Do, Korea.
Department of Chemistry, Myongji University, Myongji-Ro 116, Yongin 17058, Gyeonggi-Do, Korea.
Antioxidants (Basel). 2022 Aug 5;11(8):1525. doi: 10.3390/antiox11081525.
Oxo-carotenoids containing conjugated carbonyl groups in their chains were designed to be more efficient superoxide radical scavengers than natural carotenoids, β-carotene and canthaxanthin. A practical chain-extension method for polyene dials (e.g., crocetin dial) was also proposed based on Horner-Wadsworth-Emmons olefination. Double aldol condensation between polyene dials and acetophenones with ring substituents produced oxo-carotenoids with substituted benzene rings. The antioxidant activity of oxo-carotenoids was measured using DPPH (radical) and ABTS (cationic radical) scavenging assays and compared with the analysis with the superoxide (anionic radical) probe. An effective conjugation length by carbon-carbon double bonds is important to provide superior antioxidant activity for oxo-carotenoids, regardless of the type of radical probe used in the assay. Increasing electron density is favorable to strong antioxidant activity in DPPH, and the phenol group is favored in ABTS, whereas electron deficient oxo-carotenoids are very potent in the superoxide radical assay. All oxo-carotenoids exhibited 105151% better superoxide radical scavenging activity compared to beta-carotene (100%), whereas 38155% in DPPH and 16~96% in ABTS radical scavenging activities were observed.
链中含有共轭羰基的氧代类胡萝卜素被设计成比天然类胡萝卜素、β-胡萝卜素和角黄素更有效的超氧自由基清除剂。基于霍纳-沃兹沃思-埃蒙斯烯化反应，还提出了一种用于多烯二醇（如藏红花酸二醇）的实用扩链方法。多烯二醇与带有环取代基的苯乙酮之间的双羟醛缩合反应生成了带有取代苯环的氧代类胡萝卜素。使用DPPH（自由基）和ABTS（阳离子自由基）清除试验测定了氧代类胡萝卜素的抗氧化活性，并与超氧化物（阴离子自由基）探针分析结果进行了比较。对于氧代类胡萝卜素而言，碳-碳双键形成的有效共轭长度对于提供优异的抗氧化活性很重要，无论试验中使用何种类型的自由基探针。电子密度增加有利于在DPPH中表现出强抗氧化活性，而在ABTS中酚基团更有利，而缺电子的氧代类胡萝卜素在超氧自由基试验中非常有效。与β-胡萝卜素（100%）相比，所有氧代类胡萝卜素的超氧自由基清除活性均提高了105%151%，而在DPPH自由基清除活性中提高了38%155%，在ABTS自由基清除活性中提高了16%~96%。
