Effect of Usnic Acid on Candida orthopsilosis and C. parapsilosis

The activity of usnic acid against Candida orthopsilosis and Candida parapsilosis on planktonic and biofilm conditions was investigated by using a broth microdilution and microplate methods. Potent in vitro activities against different Candida species were obtained. The metabolic activity of sessile cells of C. parapsilosis complex was reduced by 80% at four times the 80% inhibitory concentration. The in vitro studies support further efforts to determine whether usnic acid can be used clinically to cure patients with Candida infections.

SOLID STATE ELECTROCHEMICAL BEHAVIOR of USNIC ACID AT A GLASSY CARBON ELECTRODE

The electrochemical redox behavior of usnic acid, mainly known for its antibiotic activity, has been investigated using cyclic, differential pulse and square wave voltammetry in aqueous electrolyte. These studies were carried out by solid state voltammetry with the solid mechanically attached on the surface of a glassy carbon electrode and at different pH values. Usnic acid did not present any reduction reaction. The pH-dependent electrochemical oxidation occurs in three steps, one electron and one proton irreversible processes, assigned to each of the hydroxyl groups in the molecule. Adsorption of the non-electroactive oxidation product was also observed, blocking the electrode surface. An oxidation mechanism was proposed and electroanalytical methodology was developed to determine usnic acid.

Antimycobacterial activity of lichen substances

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cromatografia em contra-corrente de gotejamento na separação de substâncias fenólicas de Neuropogon aurantiaco-ater

This work reports the separation of phenolic compounds present in the metabolic extract of the lichen Neuropogon aurantiaco-ater (Usniaceae). The crude extract was fractionated by droplet counter-current chromatography using a solvent mixture of high polarity (chloroform:methanol:water at 43:37:20, in ascending mode). The separation resulted in the isolation of usnic and protocetratic acid, which were identified by TLC, HPLC, and NMR tests.

Candida species: Current epidemiology, pathogenicity, biofilm formation, natural antifungal products and new therapeutic options

The incidence of fungal infections has increased significantly, so contributing to morbidity and mortality. This is caused by an increase in antimicrobial resistance and the restricted number of antifungal drugs, which retain many side effects. Candida species are major human fungal pathogens that cause both mucosal and deep tissue infections. Recent evidence suggests that the majority of infections produced by this pathogen are associated with biofilm growth. Biofilms are biological communities with a high degree of organization, in which micro-organisms form structured, coordinated and functional communities. These biological communities are embedded in a self-created extracellular matrix. Biofilm production is also associated with a high level of antimicrobial resistance of the associated organisms. The ability of Candida species to form drugresistant biofilms is an important factor in their contribution to human disease. The study of plants as an alternative to other forms of drug discovery has attracted great attention because, according to the World Health Organization, these would be the best sources for obtaining a wide variety of drugs and could benefit a large population. Furthermore, silver nanoparticles, antibodies and photodynamic inactivation have also been used with good results. This article presents a brief review of the literature regarding the epidemiology of Candida species, as well as their pathogenicity and ability to form biofilms, the antifungal activity of natural products and other therapeutic options. © 2013 SGM.

Liquens de Mato Grosso do Sul: estudo químico e avaliação da atividade biológica

Pós-graduação em Química - IQ