The Average Electron Density Tool for Bioisosterism in Hydrophobic Media

Area of Science:

• Computational chemistry
• Medicinal chemistry
• Molecular modeling

Background:

• Solvent effects significantly alter electronic properties of drug molecules, impacting bioisosteric design.
• Understanding these effects is crucial for predicting molecular behavior in biological systems.
• Hydrophobic environments, like protein interiors, present unique challenges for electronic property evaluation.

Purpose of the Study:

• To investigate the impact of hydrophobic solvation on the average electron density (AED) of carboxylic acid bioisosteres.
• To assess the reliability of AED as a descriptor for bioisosterism in nonpolar environments.
• To compare different solvation models (SMD and IEFPCM) for their accuracy in predicting AED.

Main Methods:

• Computed dipole moments and AED values for 63 carboxylic acid bioisosteres using B3LYP-D3-(BJ)/6-311++G-(d,p) level of theory.
• Employed the Solvation Model based on Density (SMD) to simulate hydrophobic environments with varying dielectric constants.
• Performed Atom in Molecule (AIM) analysis for detailed electronic structure investigation.

Main Results:

• AED values remained consistent across different dielectric constants in hydrophobic media.
• Both SMD and Integral Equation Formalism Polarizable Continuum Model (IEFPCM) yielded comparable AED results.
• The study confirmed the robustness of AED as a descriptor for bioisosterism.

Conclusions:

• Average electron density (AED) is a suitable tool for evaluating bioisosterism, even within nonpolar biological environments.
• The choice between SMD and IEFPCM models does not significantly affect AED predictions for solvation studies.
• These findings enhance the utility of computational methods in rational drug design and bioisosteric replacement strategies.