81620-91-9Relevant academic research and scientific papers
Stability determination of 3-bromo-2-hydroxy-N-(3,4-dimethyl-5- isoxazolyl)-1,4-naphthoquinon-4-imine in ethanol by first-derivative spectrophotometry
Dabbene,Brinon,De Bertorello
, p. 1617 - 1621 (1994)
The degradation kinetics of a new potential tripanocidal and antibacterial agent, 3-bromo-2-hydroxy-N-(3,4-dimethyl-5-isoxazolyl)-1,4-naphthoquinon-4- imine (2), in 95% ethanol, was investigated between 35 and 50 °C under room- light and light-protected conditions. The decomposition product was isolated and identified as 2-hydroxy-N-(3,4-dimethyl-5-isoxazolyl)-1,4-napthoquinon- 4-imine (1). A simple, rapid, and stability-indicating method for the determination of 2 in the presence of 1 using 'zero crossing' first- derivative spectrophotometry is reported. The validity of this method was proved using synthetic mixtures of the intact drug with its decomposition product and by statistical analysis of the calibration data. Pseudo-first- order constants for the degradation reaction of 2, obtained from linear plots of the residual concentration logarithms vs time, the calculated activation parameters E(a), ΔH((+)) and ΔS((+)) were similar under room-light and light-protected conditions. The in vitro antibacterial activity of 2 was also evaluated.
Antibacterial effect of 2-hydroxy-N-(3,4-dimethyl-5-isoxazolyl)-1,4-naphthoquinone-4-imine on Staphylococcus aureus
Bogdanov,Albesa,Sperandeo,Luna,De Bertorello
, p. 600 - 604 (1996)
The mechanism by which a new naphthoquinone derivative, the 2-hydroxy-N-(3,4-dimethyl-5-isoxazolyl)-1,4-naphthoquinone-4-imine (INQI-E) has antibacterial effect against Staphylococcus aureus was studied. The interaction of INQI-E with the bacteria was followed by absorption spectroscopy at 323 and 490 nm. The absorption band of INQI-E at 490 nm undergoes a hypochromic shift with a decrease of intensity. This effect was found to be reversible by oxygenation during the first hours of incubation. The participation of an oxidation-reduction process related to the respiratory chain was demonstrated by oxygen consumption. An increase in O2 uptake and inhibition of S. aureus growth was observed. Experiments with three inhibitors of the respiratory chain demonstrated that the pathway induced by INQI-E was antimycin-resistant and KCN- and salicylhydroxamic acid (SHAM)-sensitive, which suggests that INQI-E is capable of diverting the normal electron flow to an alternate superoxide-producing route. On the other hand, experiments with Tiron, a specific scavenger of superoxide, hindered the effect of INQI-E against S. aureus, indicating that the inhibitory growth effect of this quinone-imine is mainly due to the production of the cytotoxic superoxide radical.
