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A novel 5,10,15,20-tetrakis[4-(3-N,N-dimethylaminopropoxy)phenyl]chlorin (TAPC) was synthesized by reduction of the corresponding porphyrin TAPP with p-toluenesulfonhydrazide, followed by selective oxidation with o-chloranil. Spectroscopic properties and the photodynamic activity of these photosensitizers were compared in N,N-dimethylformamide. An increase in the absorption band at 650nm was found for the chlorin derivative with respect to TAPP. These photosensitizers emit red fluorescence with quantum yields of 0.15. Both compounds were able to photosensitize singlet molecular oxygen with quantum yields of about 0.5. Also, the formation of superoxide anion radical was detected in the presence of TAPC or TAPP and NADH. Photodynamic inactivation was investigated on a Gram-positive bacterium Staphylococcus aureus, a Gram-negative bacterium Escherichia coli and a fungal yeast Candida albicans cells. In vitro experiments showed that TAPC or TAPP were rapidly bound to microbial cells at short incubation periods. These photosensitizers, without intrinsic positive charges, contain four basic amino groups. These substituents can be protonated at physiological pH, increasing the interaction with the cell envelopment. Photosensitized inactivation improved with an increase of both photosensitizer concentrations and irradiation times. After 15min irradiation, a 7 log reduction of S. aureus was found for treated with 1μM photosensitizer. Similar result was obtained with E. coli after using 5μM photosensitizer and 30min irradiation. Also, the last conditions produced a decrease of 5 log in C. albicans cells. Therefore, TAPC was highly effective as a broad-spectrum antimicrobial photosensitizer., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Trace amounts of the widely used β-lactam antibiotics (Atbs) in waste water may cause adverse effects on the ecosystems and contribute to the proliferation of antibiotic-resistant bacteria. On these grounds, kinetic and mechanistic aspects of photosensitized degradation of Ceftriaxone (Cft) and Cefotaxime (Ctx), have been studied in pure water by stationary and time-resolved techniques. Additionally, possible implications of these photoprocesses on the antimicrobial activity of the Atbs have also been investigated. Photoirradiation of aqueous solutions of Cft and Ctx produces the degradation of both Atbs in the presence of Riboflavin (vitamin B2), a well known pigment dissolved in natural aquatic systems. The process occurs through Type I and Type II mechanisms, with effective prevalence of the former. The participation of O2(-), OH and O2((1)Δg) is supported by experiments of oxygen consumption carried out in the presence of specific scavengers for such reactive oxygen species. Microbiological assays exhibit a parallelism between the rate of Cft and Ctx photodegradation and the loss of their bactericidal capacity on Staphylococcus aureus strains. Results contribute to both understanding kinetic and mechanism aspects of the degradation and predicting on natural decay of Atbs waste water-contaminants., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Photoinactivation of Streptococcus mitis induced by zinc(II) 2,9,16,23-tetrakis[2-(N,N,N-trimethylamino)ethoxy]phthalocyanine (ZnEPc(4+)) was studied under different experimental condition in order to obtain information about the photodynamic processes and the cellular damage. A 3 log decrease in S. mitis survival was found in cell suspensions (~2×10(8) cells/mL) incubated with 2 μM ZnEPc(4+) and irradiated for 30 min with visible light (54 J/cm(2)). Also, S. mitis cells growth was not detected in broth treated with 5 μM ZnEPc(4+) under continuous irradiation. Studies of photodynamic action mechanism showed that the cells were protected in the presence of azide ion, while the addition of mannitol did not produce a significant effect on the survival. Moreover, the photocytotoxicity was increased in D2O indicating the interference of singlet molecular oxygen. On the other hand, it was found that ZnEPc(4+) interacts strongly with calf thymus DNA in solution but photocleavage of DNA was only detected after long irradiation periods. After S. mitis photoinactivation, modifications of genomic DNA were not observed by electrophoresis. In contrast, the transmission electron microscopy showed structural changes in the S. mitis cells, exhibiting mesosome-like structures. After 2h irradiation, the cytoplasm showed segregation patterns and PDI appeared to have effects on the cell wall, including variability in wall thickness. Also, the presence of bubbles was detected on the cell surface by scanning electron microscopy. However, the photodamage to the cell envelope was insufficient to cause the release of intracellular biopolymers. Therefore, modifications in the cytoplasmic biomolecules and alteration in the cell barriers could be mainly involved in S. mitis photoinactivation. It can be concluded that photosensitization by ZnEPc(4+) mainly involved a type II photoprocess, while alteration in the cytoplasmatic components and modifications in the cell envelope were the major cause for the photoinactivation of S. mitis., (Copyright © 2013 Elsevier B.V. All rights reserved.)