Carotenoid succinates were synthesized from hydroxy carotenoids and were coupled to a commercially available derivative of melatonin via amide bond for producing more powerful anti-oxidants and yet new hybrid lipophilic bifunctional molecules with additional therapeutic effects. The coupling reactions produced conjugates in acceptable to good yields. Succinylation increased the water solubility of the carotenoids, while the conjugation with melatonin resulted in more lipophilic derivatives. The conjugates showed self-assembly in aqueous medium and yielded relatively stable colloidal solutions in phosphate-buffered saline. Antioxidant behavior was measured with ABTS and the FRAP methods for the carotenoids, the carotenoid succinates, and the conjugates with melatonin. A strong dependence on the quality of the solvent was observed. TEAC values of the new derivatives in phosphate-buffered saline were found to be comparable to or higher than those of parent carotenoids, however, synergism was observed only in FRAP assays.
类胡萝卜素琥珀酸盐由羟基类胡萝卜素合成,并通过酰胺键与市售的褪黑素衍生物偶联,从而生产出更强效的抗氧化剂和具有额外治疗效果的新型混合亲脂双功能分子。偶联反应产生的共轭物收率良好。琥珀酰化增加了类胡萝卜素的水溶性,而与褪黑素共轭则产生了更多亲脂性衍生物。共轭物在水介质中显示出自组装特性,并在磷酸盐缓冲盐水中形成相对稳定的胶体溶液。类胡萝卜素、类胡萝卜素琥珀酸盐以及与褪黑素的共轭物的抗氧化性能是通过 ABTS 和 FRAP 方法测定的。结果表明,抗氧化性与溶剂的质量密切相关。研究发现,新衍生物在磷酸盐缓冲盐水中的 TEAC 值与类胡萝卜素母体的 TEAC 值相当或更高,但只有在 FRAP 分析中观察到了协同作用。