Increasing antibiotic resistance is one of the world's greatest health problems. The food chain is an important factor in the transfer of resistant germs from animals to humans. This study focuses on photodynamic inactivation (PDI), employing curcumin bound to polyvinylpyrrolidone (PVP-C) and NovaSol®-curcumin as photosensitizers, as potent tool for the decontamination of cucumber, pepper and chicken meat from Staphylococcus aureus (serving as the model for methicillin-resistant S. aureus, MRSA). Both curcumin and PVP have been approved as food additives, consequently exhibiting excellent biocompatibility. Vegetables and meat were contaminated with S. aureus and sprinkled with PVP-C and NovaSol®-curcumin at concentrations of 50 and 100 μM, respectively. Illumination was performed immediately using visible light (435 nm, 9.4 mW cm(-2), 33.8 J cm(-2)). The PDI efficiency was determined by quantitative analyses of colony forming units 24 h post illumination. Additionally, the long-term effects of the photodynamic inactivation on cucumbers were investigated by quantitative analyses of the viable bacterial fraction after 24 and 48 h. Photodynamic inactivation of S. aureus revealed a mean reduction of 2.6 log10 (99.8%) for cucumbers, 2.5 log10 (99.7%) for pepper and 1.7 log10 (98%) for chicken meat relative to control samples. The bactericidal effect compared to controls seems to last for at least 48 h. Furthermore, no visible changes of the exterior appearance of foodstuff after photodynamic decontamination were observed. Photodynamic inactivation may therefore constitute a safe, economic and effective decontamination technique, which is harmless to health and not noticeable to consumers.
Photodynamic inactivation (PDI), the light-induced and photosensitizer-mediated overproduction of reactive oxygen species in microorganisms, represents a convincing approach to treat infections with (multi-resistant) pathogens. Due to its favourable photoactive properties combined with excellent biocompatibility, curcumin derived from the roots of turmeric (Curcuma longa) has been identified as an advantageous photosensitizer for PDI. To overcome the poor water solubility and the rapid decay of the natural substance at physiological pH, we examined the applicability of polyvinylpyrrolidone curcumin (PVP-C) in an acidified aqueous solution (solubility of PVP-C up to 2.7 mM) for photoinactivation of Gram(+) and Gram(-) bacteria. Five micromolar PVP-C incubated for 5 minutes and illuminated using a blue light LED array (435 ± 10 nm, 33.8 J cm(-2)) resulted in a >6 log10 reduction of the number of viable Staphylococcus aureus. At this concentration, longer incubation periods result in a lower phototoxicity, most likely due to degeneration of curcumin. Upon an increase of the PVP-C concentration to 50 μM (incubation for 15 or 25 min) a complete eradication of Staphylococcus aureus can be achieved. As expected for a non-cationic photosensitizer, cell wall permeabilization with CaCl2 prior to addition of 50 μM PVP-C for 15 min is necessary to induce a drop in the count of the Gram(-) Escherichia coli for more than 3 log10. As both constituents of the formulation, curcumin (E number E100) and polyvinylpyrrolidone (E1201), have been approved as food additives, a PDI based on PCP-C might allow for a very sparing clinical application (e.g. for disinfection of wounds) or even for employment in aseptic production of foodstuffs.
A direct comparison of both approaches yields that the cationic curcumin derivative SACUR-3 is effective against Gram(+) and Gram(-) pathogens, whereas the formulation of PVP-CUR has a photokilling effect on the Gram(+) model strain only, but leaves the approval of curcumin as a food additive E100 unaffected. Our results suggest the applicability of SACUR-3-based PDI in dermatology, hand hygiene and food production.
Photodynamic therapy (PDT) is approved for clinical indications including several (pre-) cancers of the skin and solid tumors of the brain and the gastrointestinal tract. It operates by an acute cellular response caused by oxidation of cell components following light-induced and photosensitizer-mediated generation of reactive oxygen species. By this, PDT is capable of inducing the major types of cytotoxic responses: autophagy, apoptosis, and necrosis. As excited photosensitizer molecules react rather non-specifically with neighboring molecules, we suggest that with PDT and most (if not any) cell-localizing photosensitizers, all kinds of cellular responses can be provoked — following a strict dose-dependency, i.e. a transition from survival, over apoptosis to necrosis depending on the applied photosensitizer concentration or light dose. In this review, we briefly discuss (i) the types of cell death induced by PDT focusing on apoptosis induction, (ii) a simple experimental approach to quickly assess the dose-dependent phototoxic responses based on viability assays, and (iii) an overview of in vitro apoptosis detection methods for further in depth analyses. With this conceptual framework, we attempt to provide a rational experimental approach for initial in vitro, cell-based characterization of newly synthesized photosensitizers or formulations thereof — thus to plug the gap between subsequent in vivo evaluation and the preceding fundamental (physico-)chemical work devoted to the improvement of photosensitizing drugs based on mainly porphyrins, phthalocyanines and their derivatives.
Photodynamic therapy (PDT) is a highly selective two-step cancer treatment involving a photosensitizer and illumination with visible light in the presence of molecular oxygen. PDT is clinically approved worldwide for treating several premalignant conditions and cancer forms, especially endoscopically accessible tumors and dermatological malignancies. PDT-mediated cytotoxicity takes place via autophagy, apoptosis and necrosis, but the exact trigger mechanisms for various death-pathways are still unknown. PDT induces reactive oxygen species (ROS) through photochemical reactions. ROS can react with different macromolecules resulting in cellular damage, including oxidation of proteins. One of the known protein modifications is reversible oxidation of cysteine thiols (-SH), which in many cases constitute a redox switch to modulate protein activity and cellular signaling. Here we have examined the role of reversible oxidation of protein thiols as a potential mediator of cytotoxicity after hexylaminolevulinate-mediated photodynamic treatment (HAL-PDT) in the human epidermoid carcinoma cell line A431. Nearly 2300 proteins were found to be reversibly oxidized after HAL-PDT, of which 374 high-confidence proteins were further allocated to cellular compartments and functional networks. 115 of the high confidence proteins were associated with apoptosis and 257 have previously not been reported to be reversibly oxidized on cysteines. We find an enrichment of DNA damage checkpoint and oxidative stress response proteins. Many of these constitute potential signaling hubs in apoptosis, including ATM, p63, RSK1 p38, APE1/Ref-1 and three 14-3-3 family members. Our study represents the first comprehensive mapping of reversibly oxidized proteins subsequent to HAL-PDT. Several of the proteins constitute potentially novel redox-regulated apoptotic triggers as well as potential targets for adjuvants that may improve the efficacy of HAL-PDT and PDT using other photosensitizers.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.