Validation of Photodynamic Action via Photobleaching of a New Curcumin-Based Composite with Enhanced Water Solubility

Abstract

Motivated by the photochemical and photophysical properties of curcumin-based composites, the characteristics of a new curcumin-based water-soluble salt were investigated via absorption and fluorescence spectroscopy. Photobleaching was investigated using a set of LEDs in three different wavelengths (405 nm, 450 nm and 470 nm) to illuminate an aqueous solution of curcumin, evaluating its degradation for five different exposure times (0, 5, 15, 45 and 105 minutes). The results were compared with equivalent measurements of dark degradation and illumination in the presence of a singletoxygen quencher. Three solution concentrations (50, 100 and 150 μg/ml) were studied. To measure the fluorescence, it was used low power 405 nm excitation laser source. Time dependent photodegradation of curcumin was observed, as compared to the natural degradation of samples maintained on a dark environment. Two main absorption peaks were detected and their relation responded to both concentration and wavelength of the illumination source. A spectral correlation between absorption of curcumin and the emission bands of the sources showed an optimal spectral overlap for the 450 nm LED. For this source, photobleaching showed a less intense degradation on the presence of singlet oxygen quencher. This last result confirmed singlet oxygen production in vitro, indicating a strong potential of this composite to be used as a bluelight-activated photosensitizer.

Potential of curcumin-mediated photodynamic inactivation to reduce oral colonization

“…The present study indicates that CRM-mediated PDI has great potential and can be useful for oral or surface decontamination in dental care conditions, but the technique needs to be further improved for clinical use, because the future of PDI will depend on the interactions between clinical applications and technological innovations [44]. Furthermore, this investigation was important because, unlike many studies that assess microbial species in an isolated form, the present study investigated the oral microbiota in saliva in order to simulate the clinical environment.…”

“…An ideal photosensitizer should have low toxicity to host cells and high toxicity to the target cells when activated by the light, thereby higher CRM concentrations could improve the effect of PDI. Additionally, since CRM is a soluble compound and because it has been previously validated as PS, the use of solvent is not necessary, which is an advantage for clinical use, justifying further studies with this compound [44].…”

“…Thus, in an attempt to minimize the amount of pathogens in human saliva and thus decrease the contamination risk of dental staff and patients, the use of PDI for mouth decontamination is proposed. The study assessed the efficacy of a water-soluble mixture of curcuminoids (CRM), previously validated by Rego-Filho et al [44] in 2014 in reducing the viability of microorganisms found in human saliva.…”

Curcumin-mediated Photodynamic Therapy for the treatment of oral infections—A review

“…The literature reports the existence of synthetic and natural pigments that can be used as photosensitizers (PS) for PDT and PDI [5,8,[19][20][21][22][23]. Despite the higher stability present by the synthetic dyes, natural compounds have been largely studied and accepted, mainly because they are less prone to collateral effects and drug interactions [7][8][9][10][11][12][13][24][25][26][27]. Curcumin (CUR) is a phenolic compound, member of the curcuminoid family, which can be extracted from the rhizomes of the Curcuma longa.…”

405 nm diode laser, halogen lamp and LED device comparison in dental composites cure: an “in vitro”experimental trial

“…Again, studies have shown the potential of the use of this laser in Photodynamic Therapy in which a photosensitiser, such as curcumin is used 7) . Others have shown promising results in the treatment of the inflammatory acne 8) .…”