Phototransformation products of the alkaloid lappaconitine: Multinuclear NMR study

Polyakov, Nikolay E.; Leshina, Tatyana V.; Ткачев, А. В.; Nikitina, I. A.; Pankrushina, N. A.

doi:10.1016/j.jphotochem.2008.01.006

Cited by 6 publications

(12 citation statements)

References 9 publications

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“…4) was the second example where the participation of electron transfer stage in the process of ligand-receptor interaction was suggested and confirmed using physicochemical approach [61]. It is known that lappaconitine reveals bradycardic and hypotensive activity [64][65]. It was demonstrated using CIDNP technique, that in the presence of amino acids tyrosine and tryptophan the reaction occurs via formation of intermediate lappaconitine radical anion with following proton transfer and ether C(O)O-R bond cleavage.…”

Section: Lappaconitine Complex With Glycyr-rhizic Acidmentioning

confidence: 90%

Glycyrrhizic Acid as a Novel Drug Delivery Vector: Synergy of Drug Transport and Efficacy

Polyakov

Leshina²

2011

TOPROCJ

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Supramolecular drug delivery systems (DDS) are widely used in pharmacology during last decades for designing new preparations with improved properties. Most of fundamental and applied research in this field has been devoted to the inclusion complexes with cyclodextrins (CD), which are assumed to possess protective properties and to decrease the hydrophobic behavior of the included molecules. At present a new generation of DDS has been developing. Novel DDS are focused simultaneously on several purposes, including improved bioavailability and stability of drugs, targeted drug delivery, and enhanced activity. One of the compounds that appear to be promising is glycyrrhizic acid (or glycyrrhizin). A number of experimental facts of high therapeutic activity of glycyrrhizin conjugates have been published, but no understanding "how it works" was presented. This manuscript will highlight our attempts to answer this question using physicochemical approach, and also outline the challenges and future opportunities for medical applications of glycyrrhizin conjugates.

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Section: Lappaconitine Complex With Glycyr-rhizic Acidmentioning

confidence: 90%

Glycyrrhizic Acid as a Novel Drug Delivery Vector: Synergy of Drug Transport and Efficacy

Polyakov

Leshina²

2011

TOPROCJ

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“…7. The stages 1-4 and 6-7 have been established earlier by the analysis of spin effects, 10,[13][14][15][16] while steps 5.1-5.3 are proposed based on the analysis of the NMR spectra of photolysis products in this work. The photolysis of N-acetyl-AA is considered to involve a cleavage and photo-Fries rearrangement.…”

Section: Discussionmentioning

confidence: 99%

“…The products of the diterpenoid fragment transformation coincide with those identified earlier for LC. 14…”

Section: H-nmr Spectramentioning

confidence: 99%

“…In addition, the shortening of the LC fluorescence lifetime (2.15 ns), in comparison with N-acetyl-AA (4 ns), is most likely to reveal the process of the fluorescence quenching of the anthranilic fragment through the previously described ET from the amine group of the alkaloid to the anthranilic fragment. 10,[13][14][15][16] In this connection, the difference between LC and MA fluorescence quantum yields and lifetimes is caused by two factors: the influence of the acetyl group leading to the loss of the molecular planarity and a decrease of the electron-donating character of the amine group towards the aromatic moiety and the process of intramolecular ET. Table 2 summarizes the fluorescence data obtained for all derivatives of LC.…”

Section: Fluorescence Measurementsmentioning

confidence: 99%

“…1, a detailed mechanism of photolysis has been established by CIDNP and EPR analysis in previous studies. 10,[13][14][15][16] According to these studies, a photoreaction begins from the partially reversible intramolecular electron transfer (ET) between nitrogen located in the diterpenoid skeleton and the AA fragment with a subsequent cleavage of the ether bond. Since the anthranilic fragment is a chromophore in these molecules as well as a potential electron acceptor in redox processes, substituents have a significant impact on the efficiency of ET and subsequent photodegradation, respectively.…”

Section: Introductionmentioning

confidence: 99%

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A photochemical approach for evaluating the reactivity of substituted lappaconitines

Ageeva

Khramtsova

Plyusnin

et al. 2018

Photochem Photobiol Sci

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Lappaconitine (LC) is a natural diterpenoid alkaloid (DTA), acting as a human heart sodium channel blocker and possessing a wide range of biological activities, the cellular and molecular mechanisms of which are widely studied. This interest is due to the fact that various representatives of this DTA class show opposite biological activities. The possible reasons for this difference seem to be related to the peculiarities of the substituent effect on the drug-receptor binding process. In this work, the influence of substituents on the reactivity of LC and its derivatives has been studied by using elementary processes of photodecomposition. The given approach includes the joint analysis of the photophysical properties of the studied systems and their photodecomposition quantum yields. It allows us to trace the influence of substituents, located in the diterpenoid skeleton and anthranilic fragment, on processes in both moieties of LC. Summarizing the data obtained, an inverse dependence of fluorescence and photodegradation quantum yields has been observed. This correlation established for LCs, in particular, allows one to propose a way to evaluate the photostability of potential drugs based on fluorescence analysis. This would be appropriate for compounds in which the reactivity depends on intersystem crossing, i.e. in the cases where the initial and reacting excited states differ in multiplicity.

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Influence of Substituents on the Lappaconitine Acetylenic Derivatives Photodegradation

et al. 2015

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Phototransformation products of the alkaloid lappaconitine: Multinuclear NMR study

Cited by 6 publications

References 9 publications

Glycyrrhizic Acid as a Novel Drug Delivery Vector: Synergy of Drug Transport and Efficacy

Glycyrrhizic Acid as a Novel Drug Delivery Vector: Synergy of Drug Transport and Efficacy

A photochemical approach for evaluating the reactivity of substituted lappaconitines

Influence of Substituents on the Lappaconitine Acetylenic Derivatives Photodegradation

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