Résumé
Dermatomycosis causes highly frequent dermal lesions, and volatile oils have been proven to be promising as antifungal agents. The antifungal activity of geraniol, nerol, citral, neral and geranial (monoterpenes), and terbinafine and anidulafungin (control drugs) against seven opportunistic pathogenic yeasts and four dermatophyte species was evaluated by the Clinical and Laboratory Standards Institute microdilution tests. Monoterpenes were more active against dermatophytes than yeasts (geometric mean of minimal inhibitory concentration (GMIC) of 34.5 and 100.4 µg.ml-1, respectively). Trichophyton rubrum was the fungal species most sensitive to monoterpenes (GMIC of 22.9 µg.ml-1). The trans isomers showed higher antifungal activity than the cis. The mechanism of action was investigated evaluating damage in the fungal cell wall (Sorbitol Protection Assay) and in the cell membrane (Ergosterol Affinity Assay). No changes were observed in the MIC of monoterpenes in the sorbitol protection assay.The MIC of citral and geraniol was increased from 32 to 160 µg.ml-1 when the exogenous ergosterol concentrations was zero and 250 µg.ml-1, respectively. The monoterpenes showed an affinity for ergosterol relating their mechanism of action to cell membrane destabilization.
Résumé
Este estudo teve como objetivo avaliar a estabilidade de xaropes contendo carbocisteína, submetidos à degradação forçada, utilizando Desenho Experimental Fatorial (DEF). Os fatores avaliados foram pH (5,0; 6,5; 8,0), presença ou ausência de EDTA dissódico e metabissulfito de sódio (0,1%). Para o estudo de degradação forçada, as formulações foram submetidas a estresse térmico (50 °C e 75% UR) e oxidação com peróxido de hidrogênio a 3%. Posteriormente, as formulações foram analisadas quanto ao pH, propriedades organolépticas e teor de fármaco por CLAE-UV, nos tempos 0, 15 e 35 dias. Os resultados mostraram que as formulações submetidas à degradação forçada sofreram uma diminuição no teor do fármaco, enquanto que o pH se manteve relativamente estável. Em relação a cor, apenas as formulações que não possuíam antioxidantes mostraram-se mais escuras. A análise dos resultados do DEF mostrou interação significativa (p<0,05) para os fatores pH/metabissulfito e EDTA/metabissulfito. As formulações contendo metabissulfito em pH 5,0 apresentaram maior degradação e as formulações com metabissulfito sem EDTA também não foram eficientes para impedir a degradação da carbocisteína.
The aim of this study was to use Factorial Design (FD) to assess the stability of carbocisteine syrups subjected to forced degradation. The factors assessed were pH (5.0; 6.5; 8.0), presence or absence of disodium EDTA and sodium metabisulfite (0.1%). For the study of forced degradation, the formulations were subjected to thermal stress (50°C and 75% RH) and oxidation with 3% hydrogen peroxide. The formulations were analyzed for pH, organoleptic properties and drug content by HPLC-UV, at 0, 15 and 35 days. The results showed that the formulations exposed to forced degradation suffered a fall in drug content, while the pH remained relatively stable. Regarding the color, only the formulations without antioxidant exhibited a darker coloration. The results of FD revealed significant interactions (p<0.05) for pH/metabisulfite and EDTA / metabisulfite. Formulations containing metabisulfite at pH 5.0 showed the greatest degradation and those with metabisulfite and without EDTA were also not effective in preventing the degradation of carbocisteine.