Use of micellar media for the fluorimetric determination of ellipticine in aqueous solutions

Sbai, M.; Lyazidi, S. Ait; Lerner, Dan A.; Castillo, B. del; Martín, M. Antonia

doi:10.1016/s0731-7085(96)01759-1

Cited by 24 publications

(21 citation statements)

References 14 publications

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“…Since ellipticine has a pKa of $6 (pyridine-like nitrogen), it can be protonated in a weak acidic environment. [26,28,29] A fresh EAK16-II (0.2 mg mL À1 ) in pure water has a pH value of $4.6, which can cause the protonation of ellipticine. In addition, the peptide molecules consisting of negatively charged glutamic acid residues may help stabilize the protonated ellipticine upon interaction.…”

Section: Time Dependence Of the Formation Of Peptide-ellipticine Compmentioning

confidence: 99%

“…A similar phenomenon has been reported, in that highly negatively charged sodium dodecyl sulfate (SDS) micelles was found to stabilize protonated ellipticine in pure water. [23,28] The amount of protonated ellipticine increases during the first several hours to a maximum and then disappears when the equilibrium is established. The diminishing of the protonated ellipticine prior to equilibrium may be related to the peptide self-assembly over time and its associated events.…”

Section: Time Dependence Of the Formation Of Peptide-ellipticine Compmentioning

confidence: 99%

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Self‐Assembling Peptide as a Potential Carrier for Hydrophobic Anticancer Drug Ellipticine: Complexation, Release and In Vitro Delivery

Fung

Yang

Bhola

et al. 2008

Adv Funct Materials

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The self‐assembling peptide EAK16‐II is capable of stabilizing hydrophobic compounds to form microcrystal suspensions in aqueous solution. Here, the ability of this peptide to stabilize the hydrophobic anticancer agent ellipticine is investigated. The formation of peptide‐ellipticine suspensions is monitored with time until equilibrium is reached. The equilibration time is found to be dependent on the peptide concentration. When the peptide concentration is close to its critical aggregation concentration, the equilibration time is minimal at 5 h. With different combinations of EAK16‐II and ellipticine concentrations, two molecular states (protonated or cyrstalline) of ellipticine could be stabilized. These different states of ellipticine significantly affect the release kinetics of ellipticine from the peptide‐ellipticine complex into the egg phosphatidylcholine vesicles, which are used to mimic cell membranes. The transfer rate of protonated ellipticine from the complex to the vesicles is much faster than that of crystalline ellipticine. This observation may also be related to the size of the resulting complexes as revealed from the scanning electron micrographs. In addition, the complexes with protonated ellipticine are found to have a better anticancer activity against two cancer cell lines, A549 and MCF‐7. This work forms the basis for studies of the peptide‐ellipticine suspensions in vitro and in vivo leading to future development of self‐assembling peptide‐based delivery of hydrophobic anticancer drugs.

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Section: Time Dependence Of the Formation Of Peptide-ellipticine Compmentioning

confidence: 99%

Section: Time Dependence Of the Formation Of Peptide-ellipticine Compmentioning

confidence: 99%

Self‐Assembling Peptide as a Potential Carrier for Hydrophobic Anticancer Drug Ellipticine: Complexation, Release and In Vitro Delivery

Fung

Yang

Bhola

et al. 2008

Adv Funct Materials

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“…Besides, the addition of NaCl to adjust the ionic strength increases the ion concentration in the bulk aqueous phase, shielding the micellar charge, which explains why both species were weakly quenched by the increasing concentrations of bromide ion. The negatively charged micellar surface of SDS solubilizes the cationic species of harmane and harmine, as has also been described for ellipticine, a pyridocarbazole alkaloid (33). However, the micellar negative charge on surface prevents bromide ions from coming close to the neutral or cationic species of alkaloids and therefore the quenching effect is reduced.…”

Section: Resultsmentioning

confidence: 78%

Fluorescence quenching of β‐carboline alkaloids in micellar media. A study to select the adequate surfactant to use in analytical techniques

et al. 2005

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The study of fluorescence quenching of the fluorophores allows the localization of the alkaloids (harmane and harmine) in the micelles (SDS, CTAB, Brij-35) to be established. In aqueous micellar solutions (SDS and Brij-35) at pH 13.0, emission corresponding to the neutral or zwitterionic forms can be observed. In the presence of CTAB (pH = 13.0) it was possible to observe the emission of anionic form. These species are not present in buffered aqueous solutions at these pH values. Bromide ion was added to the different surfactant solutions and the quenching effect was studied according to the Stern-Volmer equation. In the presence of SDS the quenching effect is considerably reduced compared to the aqueous solutions without surfactants, while for Brij-35 micelles were similar to those observed in homogeneous aqueous solution. For CTAB micelles a notable fluorescence quenching was observed for the different pH values studied. The fluorescence quenching studies show that the neutral species are associated inside the micelles, instead of the ionic species (cationic, zwitterionic or anionic) remaining on the surface of the micelles. The anionic surface of SDS micelles prevents the quenching effect by anionic quenchers for both neutral and charged species.

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“…S3, ESI †), indicating a neutral form of the molecules. 22,27 As shown in the circular dichroism (CD) results (Fig. 2b), the spectrum of C6 has a negative peak at B203 nm, with a negative shoulder centering at B220 nm, indicating that C6 remained as a mixture of random coils and a-helices in aqueous solution; the molar ellipticity [y] 222 (À4400 deg cm 2 dmol À1 ) at 222 nm corresponds to B19% helical content.…”

Section: Characterization Of the C6-ept Complexmentioning

confidence: 94%

An amphipathic lytic peptide for enhanced and selective delivery of ellipticine

Ding

et al. 2016

J. Mater. Chem. B

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Cationic lytic peptides (CLPs) have shown promise in treating bacterial infection and cancer via selective disruption of bacterial or cancer cell membranes. In this work, we used a CLP, C6, as a nanocarrier for a hydrophobic anticancer agent, ellipticine (EPT). The size of the resulting C6-EPT complex was B190 nm.The in vitro studies using A549 lung cancer cells showed an enhanced anticancer activity of the C6-EPT complex compared to that of C6 or the EPT control. This enhancement was found to correlate with the membrane disruption induced by C6, which facilitated the entry of EPT into cells. More importantly, the C6-EPT complex showed a higher selectivity than that of C6 towards cancer cells upon comparison of their cytotoxicities against A549 cells and NIH-3T3 fibroblast cells. The enhanced therapeutic activity was also found in in vivo studies using an A549 tumor-bearing BALB/c nude mice model. This study provides a new CLP strategy for the development of multifunctional drug delivery systems.

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Use of micellar media for the fluorimetric determination of ellipticine in aqueous solutions

Cited by 24 publications

References 14 publications

Self‐Assembling Peptide as a Potential Carrier for Hydrophobic Anticancer Drug Ellipticine: Complexation, Release and In Vitro Delivery

Self‐Assembling Peptide as a Potential Carrier for Hydrophobic Anticancer Drug Ellipticine: Complexation, Release and In Vitro Delivery

Fluorescence quenching of β‐carboline alkaloids in micellar media. A study to select the adequate surfactant to use in analytical techniques

An amphipathic lytic peptide for enhanced and selective delivery of ellipticine

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