Relationship between antioxidant activity and ESIPT process based on flavonoid derivatives: A comprehensive analysis.

Area of Science:

• Computational Chemistry
• Photochemistry
• Natural Product Chemistry

Background:

• Antioxidant activity is crucial for health and is influenced by molecular structure.
• Excited State Intramolecular Proton Transfer (ESIPT) is a photophysical process with potential applications.
• Flavonoids are natural compounds with known biological activities, including antioxidant properties.

Purpose of the Study:

• To investigate the relationship between ESIPT and antioxidant activity in flavonoid derivatives.
• To evaluate the potential of these compounds for sunscreen applications.
• To explore the influence of molecular structure on ESIPT and antioxidant efficacy.

Main Methods:

• Density Functional Theory (DFT) and Time-Dependent DFT (TD-DFT) calculations.
• Analysis of potential energy curves and transition states for ESIPT.
• DPPH free radical scavenging assay under dark and UV radiation conditions.

Main Results:

• Three flavonoid derivatives undergo ultrafast single proton transfer in the excited state.
• Absorption spectra indicate effective UV protection, with Baicalein (Bai) showing promise for sunscreens.
• ESIPT enhances antioxidant activity, with Bai demonstrating the highest radical scavenging activity (93.4% under UV).

Conclusions:

• ESIPT significantly elevates the antioxidant activity of flavonoid derivatives, particularly in the keto* form.
• Baicalein exhibits exceptional antioxidant and UV-protective properties, attributed to its phenolic hydroxyl groups.
• This study highlights the synergistic relationship between ESIPT and antioxidant activity, opening new avenues for functional molecule development.