Invasive fungal infections have been gaining notoriety due to several factors, mainly their increasing incidence in immunocompromised patients. The aim of the present study was to evaluate the antifungal activity and ...Invasive fungal infections have been gaining notoriety due to several factors, mainly their increasing incidence in immunocompromised patients. The aim of the present study was to evaluate the antifungal activity and toxicity of the 3,4,5-trihydroxybenzoic acid (3,4,5-THB) and of its derivative, the 3,4,5-tris(acetyloxy)benzoic acid (3,4,5-TAB). The 3,4,5-THB was purchased and its derivative was obtained by purifying and characterizing performed using semisynthesis reactions (esterification), recrystallization, column chromatography and infrared analytical techniques and nuclear magnetic resonance. Minimum inhibitory concentration (MIC) and minimum lethal concentration (MLC) were determined in order to evaluate the antifungal activity of the compounds against four clinical isolates and four standard strains of Candida sp. and five clinical isolates of dermatophytes, following the Clinical and Laboratory Standards Institute protocols. The toxicity of the compounds was evaluated by determining the lethal dosis (LD50) using lethality assay of Artemia salina. The most sensitive yeasts to the 3,4,5-THB were C. albicans ATCC 10231 and C. krusei ATCC 6258, both presenting a MIC of 128 μg·mL-1. For Trichophyton sp. and Epidermophyton floccosum, the MIC was 32 μg·mL-1. The 3,4,5-TAB showed a lower inhibitory activity against Candida and dermatophyte species tested. The LD50 of 3,4,5-THB was 222.60 μg·mL-1 and the 3,4,5-TAB showed 481.69 μg·mL-1 of LD50. In conclusion, the 3,4,5-trihydroxybenzoic acid showed antifungal activity against species of medical importance, mainly dermatophytosis-causing fungi, and the 3,4,5-tris(acetyloxy)benzoic acid showed no increasing antifungal activity and toxicity in relation to the original compound.展开更多
3,4,5-Trihydroxybenzyl acid dimer has been studied by using density functional theory B3LYP method and 6-31G*,6-31G**,6-31+G* basis set.The calculaed results indicate that the title compound has C2 symmetry and exhibi...3,4,5-Trihydroxybenzyl acid dimer has been studied by using density functional theory B3LYP method and 6-31G*,6-31G**,6-31+G* basis set.The calculaed results indicate that the title compound has C2 symmetry and exhibits strong hydrogen bonding interaction,and interaction energy is 60～66 kJ/mol after basis set superposition error and zero-point vibration energy correction.There are large red-shifts for the symmetric H-O and C=O stretching vibration frequencies in the 3,4,5-triysroxybenzyl acid dimer due to forming C=O…H-O hydrogen bond.The NBO analysis shows that the charge transfer goes from the lone pairs of the proton acceptor oxygen atom to the σ*（H-O） antibonding orbital of the proton donor,their interaction stabilization energy is 91.59 kJ/mol.展开更多
文摘Invasive fungal infections have been gaining notoriety due to several factors, mainly their increasing incidence in immunocompromised patients. The aim of the present study was to evaluate the antifungal activity and toxicity of the 3,4,5-trihydroxybenzoic acid (3,4,5-THB) and of its derivative, the 3,4,5-tris(acetyloxy)benzoic acid (3,4,5-TAB). The 3,4,5-THB was purchased and its derivative was obtained by purifying and characterizing performed using semisynthesis reactions (esterification), recrystallization, column chromatography and infrared analytical techniques and nuclear magnetic resonance. Minimum inhibitory concentration (MIC) and minimum lethal concentration (MLC) were determined in order to evaluate the antifungal activity of the compounds against four clinical isolates and four standard strains of Candida sp. and five clinical isolates of dermatophytes, following the Clinical and Laboratory Standards Institute protocols. The toxicity of the compounds was evaluated by determining the lethal dosis (LD50) using lethality assay of Artemia salina. The most sensitive yeasts to the 3,4,5-THB were C. albicans ATCC 10231 and C. krusei ATCC 6258, both presenting a MIC of 128 μg·mL-1. For Trichophyton sp. and Epidermophyton floccosum, the MIC was 32 μg·mL-1. The 3,4,5-TAB showed a lower inhibitory activity against Candida and dermatophyte species tested. The LD50 of 3,4,5-THB was 222.60 μg·mL-1 and the 3,4,5-TAB showed 481.69 μg·mL-1 of LD50. In conclusion, the 3,4,5-trihydroxybenzoic acid showed antifungal activity against species of medical importance, mainly dermatophytosis-causing fungi, and the 3,4,5-tris(acetyloxy)benzoic acid showed no increasing antifungal activity and toxicity in relation to the original compound.
文摘3,4,5-Trihydroxybenzyl acid dimer has been studied by using density functional theory B3LYP method and 6-31G*,6-31G**,6-31+G* basis set.The calculaed results indicate that the title compound has C2 symmetry and exhibits strong hydrogen bonding interaction,and interaction energy is 60～66 kJ/mol after basis set superposition error and zero-point vibration energy correction.There are large red-shifts for the symmetric H-O and C=O stretching vibration frequencies in the 3,4,5-triysroxybenzyl acid dimer due to forming C=O…H-O hydrogen bond.The NBO analysis shows that the charge transfer goes from the lone pairs of the proton acceptor oxygen atom to the σ*（H-O） antibonding orbital of the proton donor,their interaction stabilization energy is 91.59 kJ/mol.
