1. Room-temperature phosphorescence of 6-bromo-2-naphthol included in beta-cyclodextrin in the presence of cyclohexane
G M Escandar, M A Boldrini Talanta. 2001 Jan 5;53(4):851-6. doi: 10.1016/s0039-9140(00)00575-0.
The formation constant for a 1:1 binary complex between 6-bromo-2-naphthol (6B2N) and beta-cyclodextrin (CD) in aqueous solution was determined by both absorptimetric and fluorimetric methods. Room-temperature phosphorescence (RTP) was induced by adding small amounts of different apolar liquids as the third component, with cyclohexane producing the strongest enhancement effect. Microcrystals formed in the ternary system seem to be necessary for obtaining phosphorescence emission. The deoxygenation by flowing nitrogen does not improve the RTP signals, while the addition of sodium sulfite as chemical deoxygenant produces quenching of the signals. The calibration graph for 6-bromo-2-naphthol in the presence of beta-CD and cyclohexane was linear for the range of concentrations between 0.04 and 1 mug ml(-1), with a detection limit of 0.04 mug ml(-1).
2. 6-Bromo-2-naphthol-piperazine (2/1)
Yan Tian, Deliang Cui Acta Crystallogr Sect E Struct Rep Online. 2008 Nov 13;64(Pt 12):o2334. doi: 10.1107/S1600536808036878.
In the title compound, 2C(10)H(7)BrO·C(4)H(10)N(2), the piperazine (pip) mol-ecule displays a chair conformation and is linked to two mol-ecules of 6-bromo-2-naphthol (bno) via O-H⋯N hydrogen bonds. Weak N-H⋯O hydrogen bonds from pip to bno mol-ecules result in chains propagating in [100]. The chains inter-act via C-H⋯π inter-actions.
3. 6-Bromo-2-naphthol from Silene armeria extract sensitizes Acinetobacter baumannii strains to polymyxin
Mingyeong Kang, Wonjae Kim, Jaebok Lee, Hye Su Jung, Che Ok Jeon, Woojun Park Sci Rep. 2022 May 20;12(1):8546. doi: 10.1038/s41598-022-11995-y.
The overuse of antibiotics has led to the emergence of multidrug-resistant bacteria, which are resistant to various antibiotics. Combination therapies using natural compounds with antibiotics have been found to have synergistic effects against several pathogens. Synergistic natural compounds can potentiate the effects of polymyxins for the treatment of Acinetobacter baumannii infection. Out of 120 types of plant extracts, only Silene armeria extract (SAE) showed a synergistic effect with polymyxin B (PMB) in our fractional inhibitory concentration and time-kill analyses. The survival rate of G. mellonella infected with A. baumannii ATCC 17978 increased following the synergistic treatment. Interestingly, the addition of osmolytes, such as trehalose, canceled the synergistic effect of SAE with PMB; however, the underlying mechanism remains unclear. Quadrupole time-of-flight liquid chromatography-mass spectrometry revealed 6-bromo-2-naphthol (6B2N) to be a major active compound that exhibited synergistic effects with PMB. Pretreatment with 6B2N made A. baumannii cells more susceptible to PMB exposure in a time- and concentration-dependent manner, indicating that 6B2N exhibits consequential synergistic action with PMB. Moreover, the exposure of 6B2N-treated cells to PMB led to higher membrane leakage and permeability. The present findings provide a promising approach for utilizing plant extracts as adjuvants to reduce the toxicity of PMB in A. baumannii infection.
