Antioxidant and Photo-antioxidant Activities of Chalcone Derivatives

Abstract

Chalcones are the starting materials for the biosynthesis of flavonoids. Flavonoids are strong antioxidants, which contain many phenolic hydroxyl group(s). However, the antioxidant activities of chalcones have been little studied. In this study, chalcones with chemical structures resembling natural chalcones were synthesized, and the effects of the hydroxyl group(s) on the A and B rings and the C3 chain connecting the A and B rings were investigated in detail. Hydroxyl group(s) on the B ring inherited the characteristics of p-coumaric acid as a precursor of chalcone, if the groups were located on 2-and/or 4-positions to the C3 chain, and showed strong antioxidant activities. The 2'-hydroxy group of the A ring cooperated with the carbonyl group on the 1'-position to provide ultraviolet rays absorbing (photo-antioxidant) activity. The carbon _ carbon double bond in the C3 chain, connecting the A ring with the B ring in a conjugated system, enhanced both antioxidant and photo-antioxidant activities. The obtained information was used in the molecular design of new polymer additives.

Relationship between Chemical Structure and Antioxidant Function of Flavonoids

“…The identification was done with Fourier transform-infrared spectroscopy (FT-IR) and 1 H-nuclear magnetic resonance (NMR Other materials, such as solvents, azo-bis-isobutyronitrile (AIBN), hydroquinone, catechol and resorcinol, 3,5-di-t-butyl-4-hydroxytoluene (BHT), and 2-hydroxybenzophenone (2-HBP) were purified by conventional methods. 2',4-Dihydroxychalcone was prepared according to the procedure described in a previous paper 3) .…”

“…In contrast, the present study revealed that the first metabolite, p-coumaric acid, shows higher radical-scavenging activity than the commercial antioxidant, BHT. p-Coumaric acid is further metabolized to a chalcone, which also acquires high photo-antioxidant activity 3) . Chalcones are present only in small amounts, probably due to their instability in plants, and are metabolized to a stable flavonoid, naringenin.…”

“…Therefore, the formation of the C ring from a chalcone weakens antioxidant and photo-antioxidant activities temporarily, but the following flavonoids gradually acquire enhanced antioxidant and photo-antioxidant activities by the acquisition of the double bond and the catechol structure. The final metabolites, quercetin and luteorin, are estimated to almost suppress photooxidation at a concentration of 0.5 mmol/dm 3 . In general, flavonoids are likely to exist in a concentration of 1 mmol/dmmmol/dmin in plants.…”

“…Investigation of the metabolism pathway of phenylalanine and tyrosine to flavonoids 1) found that phenylpropanoids such as pcoumaric acid have high antioxidant activities, but low photo-antioxidant activities 2) . In addition, chalcones derived from a phenylpropanoid, p-coumaric acid, were explained about a relationship between chemical structures and functions 3) . Chalcones have considerably higher photo-antioxidant activity, in comparison with that of p-coumaric acid, based on the A ring of the chalcone formed by malonyl CoA.…”

Simple and Efficient One Step Synthesis of Functionalized Flavanones and Chalcones

“…Chalcones (1,3-diphenyl-2-propene-1-ones) either natural or synthetic have been reported to posses varieties of biological activities [1] including anticancer, 2 antimitotic, 3 antiinflammatory, 4 antimalarial, 5 antiangiogenic, 6 antiinfective, 4j antimicrobial, 7 antioxidative, 2f-g, 8 and antiproliferative 9 activities. Similarly, flavanones (2,3-dihydro-2-phenylchromene-4-one) have also been reported to posses anticancer, 10 antimicrobial, 11 antiproliferative, 9b antiinflammatory, 10a cardiovascular, 10a antimalarial, 5c,12 antiangiogenic, 6 and hypotensive 11b activities.…”