Design, synthesis, nitric oxide release and antibacterial evaluation of novel nitrated ocotillol-type derivatives
摘要:
Nitric oxide (NO) and its auto-oxidation products are known to disrupt normal bacterial function and NO releasing molecules have the potential to be developed as antibacterial leads in drug discovery. We have designed and synthesized a series of novel nitrated compounds by combining NO releasing groups with ocotillol-type triterpenoids, which have previously demonstrated activity only against Gram-positive bacteria. The in vitro NO release capacity and antibacterial activity were sequentially evaluated and the data showed that most of the synthesized compounds could release nitric oxide. Compound 16a, 17a and 17c, with nitrated aliphatic esters at C-3 position, displayed higher NO release than other analogues, correlating to their good antibacterial activity, in which 17c demonstrated broad-spectrum activity against both Gram positive and -negative bacteria, as well as excellent synergism at sub-minimum inhibitory concentration when using with kanamycin and chloramphenicol. Furthermore, the epifluorescent microscopic study indicated that the ocotillol-type triterpenoid core may induce NO release on the bacterial membrane. Our results demonstrate that nitrated substitutions at C-3 of ocotillol-type derivatives could provide an approach to expand their antibacterial spectrum, and that ocotillol-type triterpenoids may also be developed as appropriate carriers for NO donors in antibacterial agent discovery with low cytotoxicity. (C) 2015 Elsevier Masson SAS. All rights reserved.
Electrochemical and thermodynamic behaviour of oxygenated nitrogen compounds and aromatic hydrocarbons in nitromethane, and the nitration process with NO+2 (solvation phenomena)
作者:A. Boughriet、A. Coumare、M. Wartel
DOI:10.1016/0013-4686(90)87017-v
日期:1990.2
determined at 298 K. Furthermore we have induced electrochemically the molecular association: NO +N2O4 → N2O3 (I) on a Pt electrode surface in order to reach the equilibrium constant of this reaction (I). All these findings have also allowed us to calculate the ionic dissociation constants of N2O3 and N2O4 according to N2O3 ⇆ NO+ + NO−2 (II) and N2O4 ⇆ NO+2 + NO−2 (III), respectively. It has been shown
通过线性和循环伏安法在铂电极上研究了无水脱氧硝基甲烷中含氧氮化合物的电化学性质。考虑到以前在环丁砜中的工作,已在硝基甲烷中鉴定出各种氧化偶合,涉及从II到V氧化态的氮氧化物,并在298 K下确定了其标准电势。此外,我们还通过电化学诱导了分子缔合:NO +为了达到该反应(I)的平衡常数,在Pt电极表面上具有N 2 O 4 →N 2 O 3(I)。所有这些发现也使我们能够计算出N 2的离子解离常数ø 3和N 2 ö 4根据到N 2 ö 3 ⇆NO + + NO - 2(II)和N 2 ö 4 ⇆NO + 2 + NO - 2(III)。结果表明,热力学数据可与在非极性惰性溶剂中获得的数据相比,如果在这些非质子介质中,一对夫妇的标准电势几乎不变,如果这些化学和电化学过程中涉及的氮原子被弱溶剂化(溶剂分子几乎不干预这些过程)。另一方面,我们已经对硝基甲烷中的芳香烃(ArH)进行了电化学研究,以评估其对芳香族自由基阳离子(ArH