First-Principles Density Functional Theory Studies of the Structural and Electronic Properties of Prodigiosin as a Cancer Drug

Abstract

Prodigiosin molecule, whose efficacy in the treatment of cancer has proven positive, has been studied using first-principles Density Functional Theory (DFT) methods as implemented in VASP - Vienna Ab initio Simulation Package. Initial structure of prodigiosin generated using ArgusLab 4.0.1 program was subjected to geometry optimization in the VASP program in order to determine the ground state structure. The optimized interatomic bond lengths and angles are comprehensively characterized. Important properties such as the electrostatic potential (ESP) map, HOMO-LUMO iso-contours, Mulliken charges and solvent accessibility surface area were also characterized as determined in the ArgusLab 4.0.1 software. The Mulliken charges calculated, predict the direction of delocalization of electrons in the molecule. Electrostatic potential map showed the areas of the molecule that would be susceptible to nucleophilic and electrophilic attack. As ESP predicts the most reactive part of the molecule, the chemical reactivity is also understood from its chemical potential, electrophilicity and hardness. HOMO-LUMO energy gap of the molecule also reflects the chemical reactivity, polarizability and chemical hardness of a molecule. Solvent accessibility surface area of the molecule gives better understanding on the contact surface of the molecule when used as drug in the aqueous environment such as in the human body. Finally, this study will be helpful in drug design and drug delivery of prodigiosin for cancer treatment. It is also foreseen that studies could be done on polymerization of prodigiosin molecule as its conjugate bonding system may open a new frontier of research as a promising electrically conducting polymer.