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Background: Photodynamic therapy (PDT) activates a photosensitizer by visible light to generate cytotoxic oxygen species that lead to cell death. With proper illumination, PDT is often used in applications on superficial and sub-surface lesions. Sporotrichosis infection occurs by Sporothrix fungi which causes a skin wound, worsened by Candida albicans infections. This study investigated the photosensitizing efficiency of the Ru(phen) 2 (pPDIp)(PF 6 ) 2 complex, RupPDIp, against S. brasiliensis and C. albicans., Material and Methods: RupPDIp efficiency against these fungi was tested using 450 nm (blue light and 36 J/cm 2 ) and 525 nm (green light, 25.2 J/cm 2 ) at 0.05-20 μM concentrations. To ensure PDT effectiveness, control groups were tested in the absence and in the presence of RupPDIp under light irradiation and in the dark., Results: RupPDIp eliminated both fungi at ≤5.0 μM. Green light showed the best results, eliminating S. brasiliensis and C. albicans colonies at RupPDIp 0.5 μM and 0.05 μM, respectively., Conclusion: RupPDIp is a promising photosensitizer in aPDT, eliminating 10 6  CFU/mL of both fungi at 450 nm and 525 nm, with lower light doses and concentrations when treated with the green light compared to the blue light., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Infectious diseases constitute a serious problem for human health and life. Although many bacterial and fungal infections can be successfully cured by commonly used antibiotics, a new threat emerges in the form of microbial resistance. For this reason, researchers try to find not only new active pharmaceutical ingredients for conventional antibiotherapy but also try to develop new strategies of microbial inactivation. Photodynamic antimicrobial chemotherapy, which relies on reactive oxygen species generated in situ in the presence of a photosensitizer and with the light of an appropriate wavelength, is one of them. Porphyrazines have been considered as potential photosensitizers for anticancer and antimicrobial photodynamic therapy. In this study, three tribenzoporphyrazines with dendrimeric peripheral substituents were subjected to in vitro antimicrobial photocytotoxicity study. One magnesium(II) tribenzoporphyrazine with peripheral 3,5-bis(3,5-dimethoxybenzyloxy)benzylsulfanyl substituents was synthesized and subjected to physicochemical characterization using NMR, UV-Vis, and mass spectrometry techniques. In photochemical studies this molecule revealed moderate singlet oxygen generation ability (Φ ΔDMF  = 0.12, Φ ΔDMSO  = 0.13). The other two magnesium(II) tribenzoporphyrazines applied in the biological study were 4-[3,5-di(hydroxymethyl)phenoxy]butylsulfanyl-substituted tribenzoporphyrazine and 4-[3,5-bis(benzyloxy)benzyloxy]phenyl-substituted tribenzopyrazinoporphyrazine. For the assessment, three microbial strains were chosen: Gram-positive bacteria Staphylococcus aureus ATCC 25923, Gram-negative bacteria Escherichia coli ATCC 25922, and fungal strain Candida albicans ATCC 10231. Very high activity against Staphylococcus aureus at low 10 -6  M concentration was recorded for magnesium(II) tribenzoporphyrazines with peripheral 3,5-bis(3,5-dimethoxybenzyloxy)benzylsulfanyl and 4-[3,5-di(hydroxymethyl)phenoxy]butylsulfanyl substituents with calculated log reductions of 4.4 and 4.8, respectively. It is worth noting that magnesium(II) tribenzoporphyrazine with 4-[3,5-di(hydroxymethyl)phenoxy]butylsulfanyl substituents revealed also 3.2 log reduction in bacterial growth at the concentration 10 -7 M., Competing Interests: Declaration of Competing Interest The authors declare that there is no conflict of interest, (Copyright © 2020 Elsevier B.V. All rights reserved.)

A new fullerene (BB4-PPBA) functionalized with a tertiary amine and carboxylic acid was prepared and compared with BB4 (cationic quaternary group) for antimicrobial photodynamic inactivation (aPDI). BB4 was highly active against Gram-positive methicillin resistant Staphylococcus aureus (MRSA) and BB4-PPBA was moderately active when activated by blue light. Neither compound showed much activity against Gram-negative Escherichia coli or fungus Candida albicans. Therefore, we examined potentiation by addition of potassium iodide. Both compounds were highly potentiated by KI (1-6 extra logs of killing). BB4-PPBA was potentiated more than BB4 against MRSA and E. coli, while for C. albicans the reverse was the case. Addition of azide potentiated aPDI mediated by BB4 against MRSA, but abolished the potentiation caused by KI with both compounds. The killing ability after light decayed after 24 h in the case of BB4, implying a contribution from hypoiodite as well as free iodine. Tyrosine was readily iodinated with BB4-PPBA plus KI, but less so with BB4. We conclude that the photochemical mechanisms of these two fullerenes are different. BB4-PPBA is more Type 2 (singlet oxygen) while BB4 is more Type 1 (electron transfer). There is also a possibility of direct bacterial killing by electron transfer, but this will require more study to prove., (Copyright © 2018. Published by Elsevier B.V.)

This paper reports the synthesis of silver oxide (Ag 2 O) and moxifloxacin functionalized silver oxide (M-Ag 2 O) nanoparticles for photocatalytic and antimicrobial activity. The Ag 2 O nanoparticles were synthesized by using 2 dimethyl amino ethanol as reducing agent. The BET surface area measured from N 2 adsorption method was found to be 16.89 m 2 /g. The mix (cubic and hexagonal) phase of silver oxide (Ag 2 O) nanoparticles was confirmed by X-rays diffraction (XRD). The extra diffracted peaks were observed after moxifloxacin fictionalization. The scanning electron micrographs display spherical shaped particles of different sizes. The elemental composition and weight percent of both samples were studied by energy dispersive X-ray (EDX). The decrease in the weight percent of silver with the subsequent increase in the weight percent of carbon and oxygen revealed the successful loading of moxifloxacin onto Ag 2 O NPs. The two stages of weight loss due to the removal of physisorbed and chemisorbed water was examined during thermogravimetric analysis (TGA). The optical band gap derived from the diffuse reflectance spectrum (DRS) was 1.83 eV, which corresponds to the transmittance edge of 676 nm. The Fourier transform infrared (FTIR) band at 668.56 cm -1 confirms the successful synthesis of moxifloxacin functionalized silver oxide (Ag 2 O) nanoparticles. The pure Ag 2 O nanoparticles were used for the degradation of rhodamine 6G and 98.56% dye was degraded in 330 min. The bacterial species selected for the present study were Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Candida albicans and Aspergillus Niger. Both pure and functionalized Ag 2 O NPs were screened against selected bacterial and fungal species and they showed improved activity with the volume of samples taken in wells. However, the activity of Ag 2 O NPs against fungi was found less effective than bacteria which may be due to the difference in the composition of the cell wall. Further gram-positive bacteria showed more resistance toward both samples as compared to the gram-negative bacteria. It was concluded that Ag 2 O NPs upon conjugation with moxifloxacin displayed promising antimicrobial activity., (Copyright © 2018 Elsevier B.V. All rights reserved.)

It is shown that exposure of suspensions of gram-positive Staphylococcus aureus, gram-negative Escherichia coli and yeast-like fungi Candida albicans to laser radiation of blue spectral region with 405 and 445 nm causes their growth inhibition without prior addition of exogenous photosensitizers. It is experimentally confirmed that compounds of flavin type capable of sensitizing the formation of reactive oxygen species can act as acceptors of optical radiation of blue spectral region determining its antimicrobial effect along with endogenous metal-free porphyrins (the role of endogenous porphyrins has been confirmed earlier by a number of researchers). The participation of these compounds in the antimicrobial effect of laser radiation is supported by the registration of porphyrin and flavin fluorescence in extracts of microbial cells upon excitation by radiation used to inactivate the pathogens. In addition, the intensity of the porphyrin fluorescence in extracts of microbial cells in the transition from radiation with λ = 405 nm to radiation with λ = 445 nm decreases by 15-30 times, whereas the photosensitivity of the cells under study in this transition decreases only 3.7-6.2 times. The contribution of porphyrin photosensitizers is most pronounced upon exposure to radiation with λ = 405 nm (absorption maximum of the Soret band of porphyrins), and flavins - upon exposure to radiation with λ = 445 nm (maximum in the flavin absorption spectrum and minimum in the absorption spectrum of porphyrins). The ratio between the intensity of the porphyrin and flavin components in the fluorescence spectrum of extracts depends on the type of microbial cells., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Photodynamic inactivation (PDI) has been reported to be effective to eradicate a wide variety of pathogens, including antimicrobial-resistant microorganisms. The aim of this study was to identify the potential molecular targets of PDI depending on growth phase of Candida albicans. Fungal cells in lag (6h) and stationary (48h) phases were submitted to PDI mediated by methylene blue (MB) combined with a (662±21) nm-LED, at 360mW of optical power. Pre-irradiation time was 10min and exposure times were 12min, 15min and 18min delivering radiant exposures of 129.6J/cm 2 , 162J/cm 2 and 194.4J/cm 2 , respectively, on a 24-well plate of about 2cm 2 at an irradiance of 180mW/cm 2 . Scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force spectroscopy (AFS) and Fourier transform infrared spectroscopy (FT-IR) were employed to evaluate the photodynamic effect in young and old fungal cells following 15min of irradiation. Morphological analysis revealed wrinkled and shrunk fungal cell membrane for both growth phases while extracellular polymeric substance (EPS) removal was only observed for old fungal cells. Damaged intracellular structures were more pronounced in young fungal cells. The surface nanostiffness of young fungal cells decreased after PDI but increased for old fungal cells. Cellular adhesion force was reduced for both growth phases. Fungal cells in lag phase predominantly showed degradation of nucleic acids and proteins, while fungal cells in stationary phase showed more pronounced degradation of polysaccharides and lipids. Taken together, our results indicate different molecular targets for fungal cells in lag and stationary growth phase following PDI., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Candida spp. are able to survive on hospital surfaces and causes healthcare-associated infections (HCAIs). Since surface cleaning and disinfecting interventions are not totally effective to eliminate Candida spp., new approaches should be devised. Copper (Cu) has widely recognized antifungal activity and the use of Cu-sputtered surfaces has recently been proposed to curb the spread of HCAIs. Moreover, the activity of Cu under the action of actinic light remains underexplored. We investigated the antifungal activity of Cu-sputtered polyester surfaces (Cu-PES) against azole-resistant Candida albicans and Candida glabrata under dark and low intensity visible light irradiation (4.65mW/cm 2 ). The surface properties of Cu-PES photocatalysts were characterized by diffuse reflectance spectroscopy (DRS) and X-ray fluorescence (XRF). Under dark, Cu-PES showed a fungicidal activity (≥3log 10 CFU reduction of the initial inoculum) against both C. albicans DSY296 and C. glabrata DSY565 leading to a reduction of the starting inoculum of 3.1 and 3.0log 10 CFU, respectively, within 60min of exposure. Under low intensity visible light irradiation, Cu-PES exhibited an accelerated fungicidal activity against both strains with a reduction of 3.0 and 3.4log 10 CFU, respectively, within 30min of exposure. This effect was likely due to the semiconductor Cu 2 O/CuO charge separation. The decrease in cell viability of the two Candida strains under dark and light conditions correlated with the progressive loss of membrane integrity. These results indicate that Cu-PES represent a promising strategy for decreasing the colonization of surfaces by yeasts and that actinic light can improve its self-disinfecting activity., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Candida albicans is responsible for many of the infections affecting immunocompromised individuals. Although most C. albicans are susceptible to antifungal drugs, uncontrolled use of these drugs has promoted the development of resistance to current antifungals. The clinical implication of resistant strains has led to the search for safer and more effective drugs as well as alternative approaches, such as controlled drug release using liposomes and photodynamic inactivation (PDI), to eliminate pathogens by combining light and photosensitizers. In this study, we used layer-by-layer (LBL) assembly to immobilize triclosan and acridine orange encapsulated in liposomes and investigated the possibility of controlled release using light. Experiments were carried out to examine the susceptibility of C. albicans to PDI. The effects of laser irradiation were investigated by fluorescence microscopy, atomic force microscopy, and release kinetics. Liposomes were successfully prepared and immobilized using the self-assembly LBL technique. Triclosan was released more quickly when the LBL film was irradiated. The release rate was approximately 40% higher in irradiated films (fluence of 15J/cm 2 ) than in non-irradiated films. The results of the susceptibility experiments and surface morphological analysis indicated that C. albicans cell death is caused by photodynamic inactivation. Liposomes containing triclosan and acridine orange may be useful for inactivating C. albicans using light. Our results lay the foundation for the development of new clinical strategies to control resistant strains., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Three stable synthetic mono-substituted cationic bacteriochlorins (BC37, BC38 and BC39) were recently reported to show exceptional activity (low nanomolar) in mediating photodynamic killing of human cancer cells after a 24h incubation upon excitation with near-infrared light (730 nm). The presence of cationic quaternary ammonium groups in each compound suggested likely activity as antimicrobial photosensitizers. Herein this hypothesis was tested against a panel of pathogenic microorganisms that have all recently drawn attention due to increased drug-resistance (Gram-positive bacteria, Staphylococcus aureus and Enterococcus faecalis; Gram-negative bacteria, Escherichia coli and Acinetobacter baumannii; and fungal yeasts, Candida albicans and Cryptococcus neoformans). All three bacteriochlorins were highly effective against both Gram-positive species (>6 logs of eradication at ⩽ 200 nM and 10 J/cm(2)). The dicationic bacteriochlorin (BC38) was best against the Gram-negative species (>6 logs at 1-2 μM) whereas the lipophilic monocationic bacteriochlorin (BC39) was best against the fungi (>6 logs at 1 μM). The bacteriochlorins produced substantial singlet oxygen (and apparently less Type-1 reactive-oxygen species such as hydroxyl radical) as judged by activation of fluorescent probes and comparison with 1H-phenalen-1-one-2-sulfonic acid; the order of activity was BC37 > BC38 > BC39. A short incubation time (30 min) resulted in selectivity for microbial cells over HeLa human cells. The highly active photodynamic inactivation of microbial cells may stem from the amphiphilic and cationic features of the bacteriochlorins., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Respiratory deficiency increases the sensitivity of the pathogenic fungi Candida albicans and Candida glabrata to oxidative stress induced by photodynamic therapy (PDT) sensitized by the cationic porphyrin meso-tetra (N-methyl-4-pyridyl) porphine tetra tosylate (TMP-1363). Since disruption of electron transport chain (ETC) function increases intracellular levels of reactive oxygen species in yeast, we determined whether interference with ETC assembly or function increased sensitivity to TMP-1363-PDT in C. albicans, C. glabrata and the non-pathogenic yeast Saccharomyces cerevisiae. Metabolic inhibitor antimycin A and defined genetic mutants were used to identify ETC components that contribute to the sensitivity to PDT. Inhibition of cytochrome bc(1) (Complex III) with antimycin A increases mitochondrial levels of reactive oxygen species. PDT performed following pre-treatment with antimycin A reduced colony forming units (CFU) of C. albicans and C. glabrata by approximately two orders of magnitude relative to PDT alone. A S. cerevisiae mitochondrial glutaredoxin grx5 mutant, defective in assembly of Fe-S clusters critical for Complex III function, displayed increased sensitivity to PDT. Furthermore, C. glabrata and S.cerevisiae mutants in cytochrome c oxidase (Complex IV) synthesis and assembly were also significantly more sensitive to PDT. These included suv3, encoding an ATP-dependent RNA helicase critical for maturation of cytochrome c oxidase subunit transcripts, and pet117, encoding an essential cytochrome c oxidase assembly factor. Following PDT, the reduction in CFU of these mutants was one to two orders of magnitude greater than in their respective parental strains. The data demonstrate that selective inhibition of ETC Complexes III and IV significantly increases the sensitivity of C. albicans, C. glabrata and S. cerevisiae to PDT sensitized with TMP-1363., (2010 Elsevier B.V. All rights reserved.)

Aim of the Study: Phototoxicity can be either harmful or beneficial. Yet the phototoxicity of oriental medicinal plants is an understudied area. The purpose of this study is to fill in this gap., Materials and Methods: The phototoxic potential of oriental medicinal plants was examined in vitro using photohemolysis and the Candida albicans test. Seventeen medicinal plants [Acorus gramineus (ACG), Panax ginseng C.A. (PAG), Platycodon grandiflorum (PLG), Aractylodes japonica (ATJ), Xanthium strumarium (XAS), Dioscorea batatas (DIB), Anemarrhena asphodeloides (ANA), Polygonatum sibiricum Red (PSR), Cocculus trilobus (COT), Ficus carica (FIC), Chelidonium majus var. asiaticum (CMA), Pulsatilla koreana (PUK), Agrimonia pilosa (AGP), Zanthoxylum schinifolium (ZAS), Angelica gigas (ANG), Ledebouriella seseloides (LES), and Cnidium officinale (CNO)] were selected because they showed strong fluorescence in one of our previous studies of 62 plants. We further evaluated in vivo phototoxicity in mice. 0.75 mL/kg of seed oil for Xanthium strumarium (XAS, ), or 1.25 mL/kg of extracted solutions of Atractylodes japonica (ATJ, ), Chelidonium majus var. asiaticum (CMA, ), Zanthoxylum schinifolium (ZAS, ), and Ledebouriella seseloides (LES, ) were given once, and evaluated for sunburn edema, formation of sunburn cell, decrease of epidermal Langerhans cells and local suppression of contact hypersensitivity by UVA irradiation., Results: Sixteen out of the 17 plants tested except COT showed significant photohemolysis, and 5 of those exhibited phototoxic killing of Candida albicans. The phototoxicity of oriental medicines using those 5 plants was then studied in mice. The 5 plants increased sunburn edema and formation of sunburn cell, and suppressed immune responses locally by decreasing epidermal Langerhans cells and contact hypersensitivity by UVA irradiation., Conclusions: More than a quarter of oriental medicinal plants can be phototoxic, and strong fluorescence measured by absorption and fluorescence spectra can be an easier way to screen for phototoxicity. On the other hand, the phototoxicity of the plants may also be used therapeutically. Further studies regarding the phototoxicity of active components extracted from both live and dried oriental medicinal plants are necessary., (Copyright 2009 Elsevier Ireland Ltd. All rights reserved.)

Due to the augmented number of immunocompromised patients, the infections associated to the pathogen of the genus Candida have increased dramatically in the recent years. In order to proliferate, Candida albicans can produce a germ tube formation extending from the cells. The germ tube formation is a transition state from budding to hyphal cells, and represents an essential stage for virulence. In this work we studied the effect of the photodynamic antimicrobial chemotherapy (PACT), a potential antimicrobial treatment on the germ tube formation by C. albicans. Germ tube formation was induced by goat serum after different treatments with Methylene blue (MB) and Laser (683nm). Our results demonstrated that photodynamic therapy using MB, as a photosensitizing drug; inhibits both the growth and the germ tube formation by C. albicans. Thus, our results suggest the possibility that Methylene blue, combined with light in a specific wavelength, can be used as a promising novel antifungal agent.

The aim of this study was to evaluate the effects of the laser radiation (685 nm) associated with photosensitizers on viability of different species of Candida genus. Suspensions of Candida albicans, Candida dubliniensis, Candida krusei and Candida tropicalis, containing 10(6) viable cells per milliliter were obtained with the aid of a Neubauer's chamber. From each species, 10 samples of the cell suspension were irradiated with diode laser (685 nm) with 28 J/cm2 in the presence of methylene blue (0.1 mg/ml), 10 samples were only treated with methylene blue, 10 samples were irradiated with laser in the absence of the dye, 10 samples were treated with the dye and irradiated with laser light and 10 samples were exposed to neither the laser light nor to the methylene blue dye. From each sample, serial dilutions of 10(-2) and 10(-3) were obtained and aliquots of 0.1 ml of each dilution were plated in duplicate on Sabouraud dextrose agar. After incubation at 37 degrees C for 48 h, the number of colony-forming units (CFU/ml) was obtained and data were submitted to ANOVA and Tukey's test (p<0.05). Laser radiation in the presence of methylene blue reduced the number of CFU/ml in 88.6% for C. albicans, 84.8% for C. dubliniensis, 91.6% for C. krusei and 82.3% for C. tropicalis. Despite this, only laser radiation or methylene blue did not reduce significantly the number of CFU/ml of Candida samples, except for C. tropicalis. It could be concluded that the photo activation of methylene blue by the red laser radiation at 685 nm presented fungicide effect on all Candida species studied.

Background: Photodynamic inactivation (PDI) employs visible light and a photosensitizer to inactivate cells. The technique is currently clinically used for the treatment of several malignancies. However, the PDI of microorganisms still remains in the research phase., Purpose: To study the effect of human blood plasma and human serum albumin (HSA) on the PDI of Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans., Methods: PDI experiments were performed using white light (30 mW cm-2) and the cationic 5-phenyl-10,15,20-tris(N-methyl-4-pyridyl)porphyrin chloride (TriP[4]) as photosensitizer., Results: The microorganisms could be successfully photoinactivated by TriP[4] when suspended in phosphate buffered saline (PBS). In this medium, P. aeruginosa was the most resistant microorganism. Changing the suspending medium from PBS to human blood plasma reduced the PDI of all three microorganisms. In human blood plasma C. albicans was the most resistant microorganism. The same results were obtained with 4.5% and 7% HSA/PBS suspensions., Conclusions: Albumin inhibits the PDI of S. aureus, P. aeruginosa and C. albicans in a dose dependent manner. However, our results are encouraging towards the potential future application of PDI for the treatment of superficial wound infections caused by S. aureus, P. aeruginosa and C. albicans.

Anecdotal reports suggest that the dihydropyridine calcium antagonist, nifedipine (NIF), may be phototoxic in human skin. We have studied NIF phototoxicity in vitro using UVA fluorescent tubes (Sylvania PUVA). NIF was phototoxic to Candida albicans and induced photohaemolysis both with NIF present during irradiation and with pre-irradiated drug. In V79 hamster fibroblasts, NIF (10 micrograms ml-1) was phototoxic MTT assay) 24 h after irradiation (0-112 kJ m-2); at 7.5 kJ m-2, about 70% of cells were damaged whilst at 37.5 kJ m-2, only about 45% of cells were damaged. A similar pattern was seen with pre-irradiated NIF. Absorption spectroscopy showed that the NIF absorption maximum (Amax approximately 340 nm) blue-shifted to 314 nm at low UVA doses (7.5 kJ m-2 or less) and red-shifted to 345 nm at higher doses (isosbestic point, 325 nm). Thin layer chromatography of irradiated NIF showed a single photoproduct (PP1; Amax approximately 314 nm) formed at 7.5 kJ m-2 or less which disappeared at higher UVA doses to give further photoproducts. PP1 was highly dark toxic to V79 cells (50% damage at about 5 micrograms ml-1) but PP1 pre-irradiated with UVA was non-toxic. Preliminary gas chromatography-mass spectroscopy studies suggest that PP1 is the nitroso derivative of NIF. These results indicate that NIF phototoxicity in vitro is partially mediated by initial formation of a toxic photoproduct (PP1) but, paradoxically, subsequent UVA irradiation may reduce phototoxicity. The NIF concentrations required to induce in vitro phototoxicity are much greater than therapeutic plasma levels. Unless there is skin accumulation of NIF or PP1, our in vitro results suggest that NIF may not be an important skin-photosensitizing agent in vivo.

With the aim of finding new photoactive compounds that may reduce the side effects of 8-methoxypsoralen photochemotherapy we report on some photophysical, photochemical and photobiological properties of recently synthesized pyrrolocoumarins, in particular 4-methyl-N-ethyl-pyrrolo[3,2-g]coumarin (PCNEt) which has an absorption maximum in the UV-A (320-400 nm). Laser (347 nm) flash photolysis studies showed triplet transients that were quenched by O2 and by ground state PCNEt. Singlet minus triplet spectra were broad (350-550 nm) and, at 700 nm, indicated solvated electron and radical production. PCNEt complexes with DNA in the dark and photobinds to thymine but does not form DNA cross-links. PCNEt was phototoxic in yeast with an action spectrum similar to its absorption spectrum. PCNEt showed photohaemolytic activity but was not phototoxic on guinea pig skin. These data suggest that PCNEt may photosensitize via several mechanisms: direct DNA photobinding, photodynamic action, or photoproduction of radicals.