Excimer Emission in Norepinephrine and Epinephrine Drugs with α- and β-Cyclodextrins: Spectral and Molecular Modeling Studies

Abstract

The inclusion complexation behavior of norepinephrine (NORE) and epinephrine (EPIN) with native cyclodextrins (α-CD and β-CD) were investigated by UV-visible, fluorimetry, time-resolved fluorescence, SEM, TEM, FT-IR, (1)H NMR, DSC, powder XRD and PM3 methods. Single emission was observed in aqueous solution where as dual emission (excimer) noticed in the CD solutions. Both drugs form 1:1 drug-CD complexes in lower CD concentrations and 1:2 CD-drug2 complexes in the higher CD concentrations. Time-resolved fluorescence studies indicated that both drugs showed single exponential decay in water and biexponential decay in CD. Nano-sized self-aggregated particles of drug-CD were found by TEM studies. Molecular modeling studies indicated that aliphatic chain part of the drug was entrapped in the CD cavity. Thermodynamic parameters and binding affinity of complex formation of the CD were determined according to PM3 method. The PM3 results were in good agreement with the experimental results.

Inclusion complexes of norepinephrine with β-cyclodextrin, 18-crown-6 and cucurbit[7]uril: experimental and molecular dynamics study

“…Insertion of the catechol moiety into nanocavity of host molecules is also accompanied by hydrogen bonding interaction between the rim hydroxyl groups and the polar groups on NP. 39,40 We also examined the effect of addition of 18C6 to an aqueous solution of NP to investigate the inuence of interaction of amine-group with the crown ether on the uorescence behavior of this molecule. The results in Fig.…”

“…The long wavelength band is ascribed to the excimer emission as have been reported for NP and similar molecules. 39,40 This band is believed to originate from the aggregation of NP molecules induced by interaction with the host molecules. The molecular aggregation quenches the uorescence of the monomer band and results in a new emission band at longer wavelength.…”

“…37,38 Inclusion complexes of some catecholamines, including NP, with various guests have been reported. 39,40 These studies have suggested that these molecules tend to aggregate in solution, especially at high concentrations and in the presence of host molecules. Ephedrine was reported to exhibit a strong excimer emission when present at concentrations greater than 10 4 M and when tted inside the pores of aluminophosphate frameworks, attributed to the p-p stacking of the aromatic rings of the compound.…”

Quantifying the Possible Short- and Long-term Impacts of Superoxide Redox Chemistry on Seawater pH

“…The slight increase in the absorbance with the addition of CDs can be attributed to the enhanced dissolution of the guest molecule through the detergent action of CD indicating the formation of guest/CD inclusion complexes. A clear isosbestic point observed in SDP and DMSP suggest both molecules forms 1:1 inclusion complexes with CD, whereas in SDBA absence of isosbestic point may rule out the possibility of a single equilibrium involving 1:1 complexation between the drug and CD [23][24][25][26][27][28][29]. The possibilities are proposed for this deviation: (i) more than one guest molecule can be accommodated within a single CD cavity, (ii) due to the space restriction of CD cavity more than one type of complex each having 1:1 stoichiometry may be formed and (iii) the changes detected in the absorption spectra when CD is added to the guest solutions containing methanol (1%) can also made the interaction between both compounds.…”

Host–guest inclusion complexes of hydroxytyrosol with cyclodextrins: Development of a potential functional ingredient for food application

“…One sharp endothermic peak at 53 • C in the HT curve corresponds to its melting point and is related to the crystallinity of HT (Malapert et al, 2019). Two endothermic peaks at 84 and 153 • C appeared in the thermogram of α-CD, probably due to the water loss from the CD cavities (Ho et al, 2015;Rajendiran, Mohandoss & Thulasidasan, 2014); one endothermic peak at about 168 • C appeared in β-CD's thermogram, due to β-CD's melting point (Kfoury et al, 2014(Kfoury et al, , 2015.…”