Fisetin and Robinetin antiradical activity under solvent effect: density functional theory study

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Medicinal Chemistry

Background:

• Flavonoids, such as Fisetin and Robinetin, are known for their antioxidant properties.
• Understanding their radical scavenging mechanisms is crucial for developing new therapeutic agents.
• Computational methods offer a powerful tool to investigate molecular interactions and reaction pathways.

Purpose of the Study:

• To investigate the structural and antioxidant activity of Fisetin and Robinetin.
• To elucidate the preferred radical scavenging mechanism (Hydrogen-Atom Transfer, SET-PT, SPLET).
• To determine the most reactive site and the influence of solvent effects on antioxidant activity.

Main Methods:

• Density Functional Theory (DFT) with B3LYP functional and 6-311++G (d, p) basis set.
• Gas-phase and solvent effect calculations (water, DMSO, methanol, benzene).
• Analysis of key thermodynamic parameters: BDE, IP, IE, PDE, PA, ETE.

Main Results:

• The 4 ahydroxyl group is the primary active site for radical scavenging in both Fisetin and Robinetin.
• The Hydrogen-Atom Transfer (HAT) mechanism is energetically favored over SET-PT and SPLET.
• Solvent effects significantly influence the energetic favorability of antioxidant mechanisms for each flavonol.

Conclusions:

• Fisetin and Robinetin exhibit potent antioxidant activity primarily through the HAT mechanism.
• The 4 ahydroxyl group is the key reactive site, highlighting its importance in radical scavenging.
• Solvent choice can modulate the antioxidant efficacy of these flavonols, with implications for their application.