Photodynamic Action of Synthetic Curcuminoids against Staphylococcus aureus: Experimental and Computational Evaluation

Author(s)

Melo, Nicolas J. ; Soares, Jennifer M. ; Dovigo, Livia N. ; Carmona-Vargas, Christian ; Aguiar, Antonio S. N. ; dos Passos, Adriana C. ; de Oliveira, Kleber T. ; Bagnato, Vanderlei S. ; Dias, Lucas D. ; Inada, Natalia

• Document type: Journal article
• Source: CHEMISTRY-SWITZERLAND; v. 6, n. 4, p. 20-pg., 2024-08-01.

Abstract

Natural curcumin is composed of three curcuminoids, namely curcumin (CUR), deme-thoxycurcumin (DMC) and bis-demethoxycurcumin (BDMC). These compounds are utilized in various biophotonics applications, including photodynamic therapy (PDT). This work aimed to evaluate the photodynamic action (alternative to antibiotics) of synthetic curcuminoids against Staphylococcus aureus. Herein, we evaluated an optimal proportion of the three curcuminoids mixed in solution to improve photoinactivation effects. Therefore, a set of computational calculations was carried out to understand the photodynamic action (stability and mechanism) of curcuminoids. Regarding computational analysis, the curcuminoid molecules were optimized using DFT with the hybrid exchange-correlation functional M06-2X, which includes long-range correction, and the 6-311++G(d,p) basis set. DMC and BDMC were more effective as photosensitizers than curcumin at a very low concentration of 0.75 mu M, inactivating more than five orders of magnitude of S. aureus. Theoretical UV-vis absorption spectra showed that at maximum absorption wavelengths, electronic transitions of the pi ->pi* type originated from H -> L excitations. The BDMC was more stable than the other two curcuminoids after photobleaching, and the fluorescence emission was also higher, which could lead to its usage as a fluorescence dye to track bacteria. In fact, the results of electronic structure calculations proved that the stability order of curcuminoids is CUR < DMC < BDMC. The mixture of synthetic curcuminoids was more effective in the inactivation of S. aureus compared to curcumin by itself; for all proposed mixtures, an equal or superior reduction was achieved. (AU)

• FAPESP's process: 13/07276-1 - CEPOF - Optics and Photonic Research Center
• Grantee: Vanderlei Salvador Bagnato
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC
• FAPESP's process: 20/06874-6 - Applications of technologies and synthetic methodologies developed under continuous flow conditions at LQBO-UFSCar for the preparation of molecules with biological activities and APIs
• Grantee: Kleber Thiago de Oliveira
• Support Opportunities: Regular Research Grants
• FAPESP's process: 14/50857-8 - National Institute in Basic Optics and Applied to Life Sciences
• Grantee: Vanderlei Salvador Bagnato
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 21/14446-7 - Multi-user equipment approved in grant 13/07276-1: Mass spectrometer with triple quadrupole analyzer and gas chromatography system coupled to the mass spectrometer
• Grantee: Vanderlei Salvador Bagnato
• Support Opportunities: Multi-user Equipment Program