Antioxidant Structure⁻Activity Relationship Analysis of Five Dihydrochalcones.

Area of Science:

• Biochemistry
• Natural Product Chemistry
• Pharmacology

Background:

• Dihydrochalcones are a class of flavonoids with potential health benefits.
• Understanding their antioxidant mechanisms is crucial for their application.
• Structure-activity relationships of dihydrochalcones are not fully elucidated.

Purpose of the Study:

• To comparatively analyze the antioxidant capacities of five similar dihydrochalcones.
• To investigate the reaction mechanisms underlying their antioxidant activity.
• To establish structure-activity relationships for dihydrochalcone antioxidant potential.

Main Methods:

• Ferric-reducing antioxidant power (FRAP) assay.
• Radical scavenging assays: DPPH•, ABTS•⁺, and superoxide radical (•O₂⁻).
• Ultra-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (UPLC−ESI−Q−TOF−MS/MS) for reaction product analysis.

Main Results:

• Phloretin exhibited the highest antioxidant activity across multiple assays.
• Dihydrochalcones reacted with DPPH• to form adducts and dimers, with varying products depending on structure.
• Methoxylation and specific hydroxyl group arrangements (2′,6′-di-OH) enhanced antioxidant potential.

Conclusions:

• Dihydrochalcones exert antioxidant action via electron transfer (ET), hydrogen atom transfer (HAT), and radical adduct formation.
• Methoxylation enhances ET and HAT, while glycosylation reduces these potentials and hinders radical adduct formation.
• The 2′,6′-di-OH moiety confers higher ET and HAT activity than the 2′,4′-di-OH moiety due to resonance effects.