Influence of carvacrol and thymol on the physiological attributes, enterotoxin production and surface characteristics of Staphylococcus aureus strains isolated from foods

This study evaluated the influence of the phenolic compounds carvacrol (CAR) and thymol (THY) on some physiological characteristics and on the modulation of the secretion of some staphylococcal virulence factors, that is, coagulase and enterotoxin. This study also investigated possible mechanisms for the establishment of the anti-staphylococcal activity of these compounds. Sublethal concentrations (0.3 and 0.15 µL/mL) of CAR and THY inhibited the activity of the enzymes coagulase and lipase and led to a decrease in salt tolerance. At the tested sublethal concentrations, both CAR and THY led to a total suppression of enterotoxin production. The loss of a 260-nm-absorbing material and an efflux of potassium ions occurred immediately after the addition of CAR and THY at 0.6 and 1.2 µL/mL and increased up to 120 min of exposure. Electron microscopy of cells exposed to CAR and THY (0.6 µL/mL) revealed that individual cells appeared to be deformed, with projections of cellular material. The observations of leakage of cellular material and an altered cell surface suggest that gross damage to a cell's cytoplasmic membrane, which results in a disruption in protein secretion, could be responsible for the anti-staphylococcal properties of CAR and THY.

Atividade antifúngica de maleimidas contra dermatófitos isolados de Tinea capitis / Maleimides antifunfical activity against dermatophytes from Tinea capitis

Tinea capitis é uma micose produzida pelos dermatófitos dos gêneros Trichophyton e Microsporum que parasitam os pelos e pele do couro cabeludo.Tendo em vista a necessidade de obter princípios ativos para uma possível aplicação prática no tratamento de infecções, o estudo de produtos de origem vegeral ou sintética, com atividade antifúngica vem recebendo grande ênfase. Neste trabalho foi feita avaliação da atividade antifùngica de cinco maleimidas: 3,4 dicloro N fenil etil maleimida, 3,4 dicloro N benzil maleimida, 3,4 dicloro N fenil butil maleimida, 3,4 dicloro N fenil propil maleimida e 3,4 dicloro N fenil maleimida. Tais substâncias foram testadas in vitro através do método de difusão em meio sólido,contra 20 cepas de dermatófitos, isolados de amostras clínicas de pacientes portadores de Tinea capitis. Os resultados destacaram a atividade antifúngica apresentada pelo composto 3,4 dicloro N fenil etil maleimida, inibindo 100% das cepas testadas na concentração de 200 mg/ml, e 3,4 dicloro N fenil propil maleimida que apresentou uma CIM de 6,3mg/ml.