Study on the Synthesis, Antioxidant Properties, and Self-Assembly of Carotenoid–Flavonoid Conjugates

Abstract

Flavonoids and carotenoids possess beneficial physiological effects, such as high antioxidant capacity, anticarcinogenic, immunomodulatory, and anti-inflammatory properties, as well as protective effects against UV light. The covalent coupling of hydrophobic carotenoids with hydrophilic flavonoids, such as daidzein and chrysin, was achieved, resulting in new amphipathic structures. 7-Azidohexyl ethers of daidzein and chrysin were prepared in five steps, and their azide-alkyne [4 + 2] cycloaddition with pentynoates of 8′-apo-β-carotenol, zeaxanthin, and capsanthin afforded carotenoid–flavonoid conjugates. The trolox-equivalent antioxidant capacity against ABTS•+ radical cation and self-assembly of the final products were examined. The 1:1 flavonoid–carotenoid hybrids generally showed higher antioxidant activity than their parent flavonoids but lower than that of the corresponding carotenoids. The diflavonoid hybrids of zeaxanthin and capsanthin, however, were found to exhibit a synergistic enhancement in antioxidant capacities. ECD (electronic circular dichroism) and UV-vis analysis of zeaxanthin–flavonoid conjugates revealed that they form different optically active J-aggregates in acetone/water and tetrahydrofuran/water mixtures depending on the solvent ratio and type of the applied aprotic polar solvent, while the capsanthin derivatives showed no self-assembly. The zeaxanthin bis-triazole conjugates with daidzein and with chrysin, differing only in the position of a phenolic hydroxyl group, showed significantly different aggregation profile upon the addition of water.

Fabrication of Functional Bioelastomer for Food Packaging from Aronia (Aronia melanocarpa) Juice Processing By-Products

“…Aronia has been reported to be rich in anthocyanins such as cyanidin-3-O-glucoside, cyanidin-3-O-xyloside, cyanidin-3-O-galactoside, and cyanidin-3-O-arabinoside [45]. Flavonoid glycosides are a form of sugar bound to flavonoids, which improve the physicochemical properties of hydrophobic flavonoids, including solubility, intra-and intercellular transport, chemical stability, and biological half-life [46]. Flavonoid glycosides, which are known to have higher antioxidant activity than flavonoid aglycone in vitro, are considered to be more suitable as food packaging materials [47].…”

Synthesis, Pharmacokinetic Characterization and Antioxidant Capacity of Carotenoid Succinates and Their Melatonin Conjugates

“…circular dichroism is needed for confirmation [ 41 , 42 ]. We have some recent experience of such behaviour of carotenoid-flavonoid conjugates [ 43 ].…”

Recent Advances in Bioactive Flavonoid Hybrids Linked by 1,2,3-Triazole Ring Obtained by Click Chemistry

“…Based on the antioxidant activity of the flavonoids and carotenoids, Linzembold et al (2020) reported the conjugation of daidzein and chrysin with carotenoids ( Figure 27 ). These hybrids were synthesized by Click Chemistry reaction in the presence of bis-triphenylphosphano-copper (I)-butyrate complex and DCM, giving rise to compounds 76a – 76b and 77a – 77b with 40–88% yield [ 116 ]. The trolox-equivalent antioxidant capacity (TEAC) of the synthetic conjugates was investigated towards ABTS •+ radical cation.…”