Study of the electrochemical betanidin oxidation path using computational methods

Area of Science:

• Biochemistry
• Computational Chemistry

Background:

• Betalains possess significant bioactive potential, making them valuable for the food, drug, and cosmetic industries.
• The properties and applications of betalains are heavily influenced by physicochemical conditions, particularly pH.
• Betanidin is a central molecule in the betalain family, critical for understanding pigment oxidation.

Purpose of the Study:

• To systematically elucidate the oxidation mechanism of betanidin.
• To determine the influence of pH on the oxidation pathways of betanidin.
• To provide a multidisciplinary study crucial for betalain applications.

Main Methods:

• Computational analysis using B3LYP/6-31+G(d,p)/SMD methodology.
• Determination of pKa and oxidation potential values for betanidin's protic groups.
• Inclusion of six explicit water molecules to refine solvation-free energy calculations.
• Cyclic voltammetry simulations to correlate computational findings with experimental electrochemical data.

Main Results:

• The study determined the pKa and oxidation potential values for betanidin under various conditions.
• A detailed oxidation mechanism for betanidin was constructed and analyzed across different pH levels.
• The primary oxidation pathway involves a concerted electron-proton transfer followed by sequential electron and proton transfers.

Conclusions:

• The oxidation of betanidin can lead to either an o-quinone product or a quinone methide molecule.
• The findings provide fundamental insights into betalain chemistry, supporting their industrial applications.
• This research establishes a computational and mechanistic framework for studying betalain oxidation.