Molecular modeling parameters predict antioxidant efficacy of 3-indolyl compounds

Area of Science:

• Medicinal Chemistry
• Computational Chemistry
• Toxicology

Background:

• Dietary constituents like indole-3-carbinol exhibit chemoprotective properties.
• These compounds function partly through radical and electrophile scavenging mechanisms.
• Existing chemoprotective indoles possess intrinsic toxicity, necessitating the development of improved analogs.

Purpose of the Study:

• To identify key molecular features determining antioxidant activity in indoles.
• To guide the design of novel chemoprotective indoles with reduced toxicity.
• To establish predictive models for antioxidant potential in indole derivatives.

Main Methods:

• Employed molecular graphic and quantum-mechanical analyses on eight structurally related 3-indolyl compounds.
• Assessed antioxidation potential using in vitro lipid peroxidation assays.
• Correlated antioxidant activity with electronic, polar, and steric molecular parameters.

Main Results:

• Electronic features of the 3-methylene carbon and 1-nitrogen were not predictive of antioxidant potency.
• Antioxidant efficacy was most strongly predicted by molecular size parameters.
• Energy of electron abstraction, calculated from heat of formation differences, significantly correlated with antioxidant potential.
• A multiple linear regression model (r2 = 0.97) incorporating heat of formation, molecular weight, log P, and dipole moment accurately predicted antioxidant efficacy.

Conclusions:

• Molecular size and electron abstraction energy are critical determinants of antioxidant activity in 3-indolyl compounds.
• Computational and molecular parameters can effectively predict the chemoprotective potential of indoles.
• Findings facilitate the rational design of safer and more effective chemoprotective indole derivatives.