Juliana Pereira Lyon

Photodynamic Therapy: Porphyrins and Phthalocyanines as Photosensitizers

The present work is focussed on the principles of photodynamic therapy (PDT), emphasizing the photochemical mechanisms of reactive oxygen species formation and the consequent biochemical processes generated by the action of reactive oxygen species on various biological macromolecules and organelles. This paper also presents some of the most used photosensitizers, including Photofrin, and the new prototypes of photosensitizers, analysing their physicochemical and spectroscopic properties. At this point, the review discusses the therapeutic window of absorption of specific wavelengths involving first- and second-generation photosensitizers, as well as the principal light sources used in PDT. Additionally, the aggregation process, which consists in a phenomenon common to several photosensitizers, is studied. J-aggregates and H-aggregates are discussed, along with their spectroscopic effects. Most photosensitizers have a significant hydrophobic character; thus, the study of the types of aggregation in aqueous solvent is very relevant. Important aspects of the coordination chemistry of metalloporphyrins and metallophthalocyanines used as photosensitizers are also discussed. The state-of-the-art in PDT is evaluated, discussing recent articles in this area. Furthermore, macrocyclic photosensitizers, such as porphyrins and phthalocyanines, are specifically described. The present review is an important contribution, because PDT is one of the most auspicious advances in the therapy against cancer and other non-malignant diseases.

Photodynamic therapy for pathogenic fungi.

Photodynamic therapy (PDT) is a minimally invasive approach, in which a photosensitiser compound is activated by exposure to visible light. The activation of the sensitiser drug results in several chemical reactions, such as the production of oxygen reactive species and other reactive molecules, whose presence in the biological site leads to the damage of target cells. Although PDT has been primarily developed to combat cancerous lesions, this therapy can be employed for the treatment of several conditions, including infectious diseases. A wide range of microorganisms, including Gram positive and Gram negative bacteria, viruses, protozoa and fungi have demonstrated susceptibility to antimicrobial photodynamic therapy. This treatment might consist of an alternative to the management of fungal infections. Antifungal photodynamic therapy has been successfully employed against Candida albicans and other Candida species and also against dermatophytes. The strain‐dependent antifungal effect and the influence of the biological medium are important issues to be considered. Besides, the choice of photosensitiser to be employed in PDT should consider the characteristics of the fungi and the medium to be treated, as well as the depth of penetration of light into the skin. In the present review, the state‐of‐the‐art of antifungal PDT is discussed and the photosensitiser characteristics are analysed.

Raman spectroscopy: A powerful technique for biochemical analysis and diagnosis

The present work focuses on the recent applications of Raman spectroscopy (RS) on biochemical analysis and diagnosis of several biological materials with or without pathological alterations. Important published works about Raman spectroscopy and its use for medical applications were critically reviewed, including articles form our group in order to evaluate the state of the art of the subject. The potential for sample characterization with RS associated to the possibility of analysisin situ makes this instrumental technique in a very auspicious tool of biochemical analysis. RS can promote a significant improvement in the chemical identification and characterization of biological systems, clinical diagnosis and prognosis regarding several diseases and quality of life of innumerous patients. The spectroscopic evaluation is based on the analysis of the Raman spectrum regarding the identification of fingerprint bands of main biological macromolecules, such as nucleic acids, proteins and fat, present in the tissue structure. This review evaluates the employment of RS in diagnosing such pathological manifestations as well as the efforts focused on the instrumental development to biomedical applications. Furthermore, advantages and limitations of this kind of approach are discussed in order to improve the biochemical analysis and diagnosis of several diseases.

Comparison between E-test and CLSI broth microdilution method for antifungal susceptibility testing of Candida albicans oral isolates.

Thirty Candida albicans isolated from oral candidosis patients and 30 C. albicans isolated from control individuals were studied. In vitro susceptibility tests were performed for amphotericin B, fluconazole, 5-flucytosine and itraconazole through the Clinical and Laboratorial Standards Institute (CLSI) reference method and E test system. The results obtained were analyzed and compared. MIC values were similar for the strains isolated from oral candidosis patients and control individuals. The agreement rate for the two methods was 66.67% for amphotericin B, 53.33% for fluconazole, 65% for flucytosine and 45% for itraconazole. According to our data, E test method could be an alternative to trial routine susceptibility testing due to its simplicity. However, it can not be considered a substitute for the CLSI reference method.

Evaluation of adhesion to buccal epithelial cells in Candida species obtained from denture wearers after exposure to fluconazole.

The aim of this study was to assess the adhesion ability by Candida spp. obtained from denture wearer patients with and without denture stomatitis and the possible reduction in adhesion after exposure to fluconazole. Nine C. tropicalis, five C. glabrata and two C. parapsilosis obtained from the oral cavity of patients with denture stomatitis and 11 C. tropicalis, nine C. glabrata and six C. parapsilosis obtained from the oral cavity of denture wearers with normal palatal mucosa were compared for adhesion ability to buccal epithelial cells (BEC) and reduction in adhesion after exposure to fluconazole. Candida spp. obtained from denture stomatitis patients were more adherent to BEC, and there was a reduction in adhesion after exposure to fluconazole in all the species tested. Our results demonstrated that exposure to fluconazole reduces Candida spp. adherence to BEC. These results also suggest that adhesion, even in non‐albicans species, could be factors that, along with predisposing conditions related to the host, determine if an individual will develop disease or remain as a healthy carrier and confirm that fluconazole has an impact in the adherence ability in Candida spp.

Antifungal suscepitibility profile of candida spp. oral isolates obtained from denture wearers

Denture stomatitis is an inflammatory condition that occurs in denture wearers and is frequently associated with Candida yeasts. Antifungal susceptibility profiles have been extensively evaluated for candidiasis patients or immunosupressed individuals, but not for healthy Candida carriers. In the present study, fluconazole, itraconazole, voriconazole, terbinafine and 5-flucytosin were tested against 109 oral Candida spp. isolates. All antifungal agents were effective against the samples tested except for terbinafine. This work might provide epidemiological information about Candida spp. drug susceptibility in oral healthy individuals.

Azure dyes as new photosensitizer prototypes to application in photodynamic therapy against Candida spp.

Infections caused by Candida albicans are of increasing concern, especially considering immunodepressed patients. The toxicity of most antifungal agents, the great number of cases with recidives, as well as the emergence of resistant samples has provoked the evaluation of new forms of therapy. In this context, the photodynamic therapy (PDT) presents auspicious antimicrobial properties, stimulating the development of trials employing several kinds of photosensitizers. In the present work, the application of different kind of Azure dyes as photosensitizer in PDT against C. albicans was evaluated through instrumental measurements of electronic spectroscopy. In fact, the values of optical density were a precise indicator of the growth inhibition of the microorganisms. Indeed, Azures are phenothiazinium derivatives that constitute a very relevant class of compounds with several biomedical applications, such as photoantimicrobial therapy against local bacterial infection, tuberculosis, trypanosomi- asis, malaria, Rickettsia, yeasts, viral infection n and cancer. Azure A, Azure B, Azure A thiocyanate, Azure B BF4 ,A zure A eosinate are the dyes tested against C. albicans. The results denoted completely distinct behaviors to the different types of Azure compound evaluated in this work. In fact, Azure A and Azure A eosinate presented significant results when irradiated with 56 J/cm 2 , since the growth inhibition of C. albicans reached approximately 60%. This Azure compounds have significant potential to be employed as photosensitizer (PS) in PDT, especially in cases of mucocutaneous candidosis. The spectroscopic evaluation was very effective to the detection of slight alterations in the growth of the microorganisms, denoting that this kind of analysis is an excellent alternative to determine growth inhibition of Candida albicans. The experimental data are discussed in details in agreement with recent results from literature.

Antifungal susceptibility profile of Trichosporon isolates: correlation between CLSI and etest methodologies

The aim of the present study was to evaluate the antifungal susceptibility profile of Trichosporon species isolated from different sources employing the Clinical and Laboratory Standards Institute (CLSI) method and E-test method. Thirty-four isolates of Trichosporon spp. and six CBS reference samples were tested for their susceptibility to Amphotericin B, 5-flucytosine, Fluconazole, Itraconazole, Voriconazole and Terbinafine. All species showed high Minimun Inhibitory Concentrations (MIC) for Itraconazole and susceptibility to Fluconazole, The comparison among the results obtained by the CLSI method and E-test revealed larger discrepancies among 5-flucytosine and Itraconazole. The present work provides epidemiological data that could influence therapeutic choices. Furthermore, the comparison between different methodologies could help to analyze results obtained by different laboratories.

Candida albicans: genotyping methods and clade related phenotypic characteristics

Several molecular methods, such as Southern blotting hybridization, Multilocus Sequence Typing, and DNA microsatellite analysis, have been employed to genotype Candida albicans. The genotype analysis allows to group strains in clades, that is, a group composed of one ancestor and its descendants. These genotype studies demonstrate that clades distribution is influenced by geographic area as well as that antifungal resistance is associated with particular clades. These findings suggested that C. albicans reproduces mainly in a clonal manner, with certain degree of DNA microevolution. Additionally, virulence factors and site of isolation have also been associated with clade specificity. The present article is a brief review about the methods used for Candida genotyping and the correlated clade systems established. Special emphasis is given to Ca3 hybridization, MLST, and Microsatellites. The present work is also focused on the phenotypic and physiological traits associated with Candida clades.

Inhibition of Virulence Factors of Candida spp. by Different Surfactants

Candida yeasts are opportunistic pathogens responsible for infections in immunocompromised individuals. Among the virulence factors present in these yeasts we can mention the ability to adhere to host cells, exoenzyme production and germ tube formation. Several compounds, such as antifungal agents, plants extracts, protein inhibitors and surfactants, have been tested regarding their capacity in inhibit Candida spp. virulence factors. Among these compounds, a significant lower number of works are focused on the inhibition action caused by different types of surfactant. The present work aimed to evaluate the effect generated by the surfactants cetyltrimethylammonium chloride (CTAC), sodium dodecyl sulfate (SDS), N-hexadecyl-N–N′-dimethyl-3-ammonio-1-propane-sulfonate (HPS) and octylphenoxypolyethoxyethanol (Triton X-100) on the viability, adhesion ability and exoenzyme production by Candida species. CTAC and HPS were capable to inhibit Candida spp. growth at very low concentrations. All surfactants demonstrated to be capable to inhibit the adhesion of Candida species to buccal epithelial cells (BEC) and the proteinase production. On the other hand, the phospholipase production remained unaltered after the treatment with these compounds. The present data denote that cationic and zwitterionic surfactants are interesting prototypes of inhibitory agents against Candida spp., which is probably associated with the cationic punctual charge of both surfactants. The results are discussed in details in agreement with recent reports from literature.