An ESR study of thermal and photo-induced formation of radicals from anthralin and acylated derivatives

Lambelet, Pierre; Prior, Elizabeth; Löliger, J.; Shroot, Braham

doi:10.1039/p29900001509

Cited by 4 publications

(3 citation statements)

References 13 publications

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“…We interpret the temperature profile for radical formation as indicating a minimum activational energy requirement for radical production followed by steady state conditions of radical formation and decay increasingly favoring production of the radical over decay as the temperature continued to increase. The hyperfine splitting constants (hfsc) of the radical (Table 2) are similar to those previously reported by Davies and co-workers (25) and Lambelet and co-workers (28). The simulated spectrum is shown in Figure IB.…”

Section: Resultssupporting

confidence: 85%

“…Polymeric "anthralin brown" free radical products are formed in the skin after treatment with the antipsoriatic 9-anthrone drug commonly known as anthralin (1,8dihydroxy-9-anthrone, Scheme 1,1) (17,18). Other free radical species including oxygen-centered radicals (19)(20)(21)(22)(23)(24) and 9-anthron-10-yl radicals (25)(26)(27)(28)(29) are also formed during the autoxidation of anthralin. The possible role of these radicals in mediating the biological effects of the drug is uncertain and is the subject of continuing interest.…”

Section: Introductionmentioning

confidence: 99%

“…Unfortunately, the EPR spectra obtained under those conditions do not reveal enough hyperfine structure to completely characterize the radicals. It has been shown, however, that thermolysis and/or photolysis of 9-anthrones produces good, high resolution EPR spectra of 9-anthron-10-yl radicals in nonpolar environments (25,27,28). Therefore, in order to investigate the nature of the primary free radicals formed by 9-anthrones in nonpolar environments, in the present study we have used thermolysis and EPR spectroscopy to generate and study free radicals from a series of 9-anthrones of known biological activities (Table 1) in nonpolar solvents.…”

Section: Introductionmentioning

confidence: 99%

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An EPR Study of Free Radicals Formed by Antipsoriatic and Tumor-Promoting 9-Anthrones in Nonpolar Solvents

Motten

Sik²,

Chignell³

et al. 1994

Chem. Res. Toxicol.

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Certain 9-anthrone derivatives are useful in treating psoriasis and are also known to be tumor promoters in mouse skin. Their therapeutic use is accompanied by side effects of severe skin inflammation, irritation, and staining. The precise biochemical mechanisms of therapeutic action, tumor promotion, and side effects are presently uncertain, although the corresponding 9-anthron-10-yl radicals have been proposed as important intermediates. In order to gain insight into the possible role of anthrone-derived radicals in mediating the biological effects of these compounds, in the present study free radicals from a number of anthrone derivatives were generated by thermolysis in nonpolar solvents. Hyperfine splitting constants (hfsc) of the radicals were determined by electron paramagnetic resonance (EPR) spectroscopy. The experimentally determined hfsc's were also compared with spin densities obtained by molecular calculations (MOPAC 6.0). The experimental and theoretical data were found to be consistent in all cases. The formation of 9-anthron-10-yl radicals appears to be a general phenomenon among 9-anthrones regardless of therapeutic or tumor-promoting effectiveness, although there is a trend toward easier radical formation for the more active compounds.

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Section: Resultssupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

An EPR Study of Free Radicals Formed by Antipsoriatic and Tumor-Promoting 9-Anthrones in Nonpolar Solvents

Motten

Sik²,

Chignell³

et al. 1994

Chem. Res. Toxicol.

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ChemInform Abstract: An ESR Study of Thermal and Photoinduced Formation of Radicals from Anthralin (I) and Acylated Derivatives.

Lambelet¹,

Prior²,

Loeliger³

et al. 1990

ChemInform

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ChemInform Abstract In order to improve therapeutic effectiveness for the treatment of psoriasis, the pharmacon anthralin (I) itself and several of its analogues are examined. Thermolysis (120 rc C) or photolysis of (I) leads to the radical (II), as well generated from the 10,10'-didehydrodimer. The ESR spectral data observed provide the basis of a hypothesis concerned with radical involvement in psoriasis therapies.

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The relevance of secondary radicals in the mode of action of anthralin

Lambelet¹,

Ducret²,

Löliger³

et al. 1990

Free Radical Biology and Medicine

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An ESR study of thermal and photo-induced formation of radicals from anthralin and acylated derivatives

Cited by 4 publications

References 13 publications

An EPR Study of Free Radicals Formed by Antipsoriatic and Tumor-Promoting 9-Anthrones in Nonpolar Solvents

An EPR Study of Free Radicals Formed by Antipsoriatic and Tumor-Promoting 9-Anthrones in Nonpolar Solvents

ChemInform Abstract: An ESR Study of Thermal and Photoinduced Formation of Radicals from Anthralin (I) and Acylated Derivatives.

The relevance of secondary radicals in the mode of action of anthralin

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