Results in Chemistry (Jun 2024)
Analysis of non-linear optical properties of phytochemical photosensitizers in cancer photodynamic therapy by quantum computational
Abstract
Rationale: Photodynamic therapy (PDT) is based on the reactive oxygen species (ROS) generated by light-activated photosensitizers in the presence of oxygen. Phytochemicals are promising natural photosensitizers, offering a potentially less toxic alternative for cancer treatments. Nonlinear optics (NLO) phenomena, such as second-harmonic generation (SHG), third-harmonic generation (THG), and two-photon absorption (TPA), can enhance light interaction, benefiting photosensitizing applications in PDT. Analyzing the NLO properties of phytochemicals can optimize their use in PDT by improving photosensitizer performance and efficacy. Aim: This study aims to examine the NLO properties of selected phytochemicals in a reported polyherbal formulation to understand their potential as effective photosensitizers in PDT, thereby advancing cancer treatment options. Methods: Quantum computational calculations were conducted at the B3LYP/6311 G++(d,p) level of theory to unveil crucial information about structural geometry and nonlinear optical properties. Results: The bandgap of aloe emodin, emodin, curcumin, scopoletin berberine, furanocoumarin, rubiadin are 3.279 eV, 3.395 eV, 3.247 eV, 3.930 eV, 2.878 eV, 4.463 eV and 3.546 eV, respectively. The results highlight berberine as the most reactive compound, demonstrating high softness and low hardness. Curcumin and furanocoumarin exhibit distinct electron-donating and accepting tendencies, respectively. In the MESP map of furanocoumarin, scopoletin, and rubiadin the electro-negative region is highly oriented around the ketone group (=O) and partially at another O atom in the pentagon. The compensating electropositive charge was distributed elsewhere. In aloe emodin, emodin, and curcumin the electronegativity was distributed around the ketone group while high electropositivity was observed around the substituted hydroxyl functional groups. In berberine electro negative region is very small and it is more electro-positive in nature. All the selected compounds have significantly greater dipole moment than standard urea (1.3732 Debye), specifically scopoletin and curcumin has 8 times greater value than urea. Concerning chemical potential, curcumin emerges as easily reactive, than berberine. The evaluation of NLO properties, including dipole moment (µ), polarizability (α), and mean first hyperpolarizability (β), underscores the superiority of berberine, making it highly reactive and easily activated during laser light irradiation. Discussion and conclusion: Berberine exhibits superior NLO properties, marked by high reactivity, substantial softness, and significant first hyperpolarizability, making it the most effective photosensitizer among the studied phytochemicals for enhancing PDT efficacy in cancer treatments.
