Natural Photosensitizers in Antimicrobial Photodynamic Therapy

Abstract

Health problems and reduced treatment effectiveness due to antimicrobial resistance have become important global problems and are important factors that negatively affect life expectancy. Antimicrobial photodynamic therapy (APDT) is constantly evolving and can minimize this antimicrobial resistance problem. Reactive oxygen species produced when nontoxic photosensitizers are exposed to light are the main functional components of APDT responsible for microbial destruction; therefore, APDT has a broad spectrum of target pathogens, such as bacteria, fungi, and viruses. Various photosensitizers, including natural extracts, compounds, and their synthetic derivatives, are being investigated. The main limitations, such as weak antimicrobial activity against Gram-negative bacteria, solubility, specificity, and cost, encourage the exploration of new photosensitizer candidates. Many additional methods, such as cell surface engineering, cotreatment with membrane-damaging agents, nanotechnology, computational simulation, and sonodynamic therapy, are also being investigated to develop novel APDT methods with improved properties. In this review, we summarize APDT research, focusing on natural photosensitizers used in in vitro and in vivo experimental models. In addition, we describe the limitations observed for natural photosensitizers and the methods developed to counter those limitations with emerging technologies.

Liposome Photosensitizer Formulations for Effective Cancer Photodynamic Therapy

“…PDT was approved in several countries for treating cancer after its approval for recurrent bladder cancer treatment by the Canadian Health Protection Branch [ 1 ]. PDT depends on the interaction of a photosensitizer (PS), delivered to target tissues, and with the light of a specific wavelength in the presence of molecular oxygen dissolved in the cytoplasm [ 16 , 17 , 18 , 19 , 20 , 21 , 22 ]. Upon light absorption, the PS molecules are transferred from the ground state to an excited singlet state and then to a triplet excited state via the intersystem crossing.…”

“…Two classes of PSs exist: Porphyrin PSs (three generations) and non-porphyrin PSs [ 27 ]. First-generation PSs (such as hematoporphyrins) have been developed and undergone clinical trials for more than 40 years [ 16 ]. However, they suffered various drawbacks, including (i) poor tissue penetration, (ii) low chemical stability, (iii) activation when irradiated with wavelengths below 650 nm, (iv) causing skin hypersensitivity reactions, and (v) low elimination rates and long half-lives.…”

Curcumin and Its New Derivatives: Correlation between Cytotoxicity against Breast Cancer Cell Lines, Degradation of PTP1B Phosphatase and ROS Generation

“…The absorption spectrum range for curcumin is between 300 and 500 nm with a maximum absorption at 435 nm. Many scientific articles indicate that curcumin can be used as a photosensitizer in photodynamic therapy, both against cancer and bacterial cells [ 32 , 33 , 34 ]. In our study, we observed the viability of MDA-MB-231 cells treated with curcumin and compound 5 in concentrations of 25 µM using a real-time fluorescence microscope.…”

Latest Innovations and Nanotechnologies with Curcumin as a Nature-Inspired Photosensitizer Applied in the Photodynamic Therapy of Cancer

“…The perfect PS should accumulate, especially in unhealthy cells, and when light is applied, it should produce toxic species that will destroy the target tissue. Characteristics of an ideal PS are the following: high absorption with maximum absorption coefficient in longer wavelengths, close to the red/infrared spectrum with deeper penetration, to make it possible to deal with grand tumors; better adhesion and fixation in unhealthy tissues than in normal ones; reliable and easy dissoluble in biological systems, permitting intravenous management and fast elimination from the organism after PDT, without residual sensitivity of the skin to light or long-term photosensitization; very good chemical balance and insignificant toxic effect on cells in the absence of light or in low darkness; long triplet lifespan and high triplet state effect, as well as high efficiency for triplet formation and singlet oxygen generation; reduced photobleaching and genuine fluorescence, low production price [6,[23][24][25][26].…”