Influence of Ultraviolet Light, Various Temperatures, and Zinc Ions on Anthralin (Dithranol)

Abstract

The changes of anthralin under various physical conditions (temperature, ultraviolet irradiation) were investigated by biochemical assay (inhibition of G-6-PDH activity), by oxygen monitor (increased oxygen consumption in the presence of zinc ions), and by recording the absorption spectra. Higher temperatures and exposure to ultraviolet light provoke the formation of a biochemically highly active compound within short periods of time. In clinical therapy, this compound may easily be formed when anthralin is used together with ultraviolet irradiation (Ingram method). Changes in the biochemical activity of anthralin are accompanied by changes in the absorption spectra. Oxidation (e.g. in the presence of zins ions) or inhibition of oxidation (e.g. in the presence of salicylic acid) may easily be detected by spectroscopic assay.

Anthralin and its acetyl esters: spectroscopic properties and enzyme inhibitory activity

“…We have shown that an anthracene spectrum develops during daylight incubation of anthralin in buffered bovine serum albumin solution (pH 6-8), whilst in the dark, the molecule remains in the henzophenone state. This experiment points to the fact that the enzyme inhihiting species (Raab & Gmeiner, 1975) is the anthracenetriol anion already mentioned. We elaborated a technique for anthralin inhibition experiments with glucose-6-phosphate-dehydrogenase to avoid degradation of anthralin and diminish auto-degradation of the enzyme.…”

The Mechanism of Photochemotherapy

“…In a wide dish, the test and control solutions were irradiated with an ultra violet lamp (Hanau S 300) under steady stirring and cooling [5]. The distance between the ultraviolet source and the surface of the solutions measured 40 cm, the angle of irradiation was 90 .…”

Pharmacology of the Skin II

“…UV radiation and zinc ions were thought to be of importance with respect to anthralin stability (RAAB and GMEINER 1975). It would appear that base and oxygen are of equal relevance (COLIN et al 1981) and as a result stable formulations are best prepared under oxygen-free conditions.…”

“…Early ideas on the inhibitory potency of anthralin on enzymes regulating glucose utilization, such as glucose-6-phosphate dehydrogenase (G6-PDH), the key enzyme in the hexose monophosphate shunt, which is elevated in psoriasis (RASSNER 1972), have to be reconsidered in the light of work with irradiated solutions of anthralin. RAAB and GMEINER (1975) suggested that the potent inhibitor of this enzyme was a decomposition product. It has been established by CAVEY et al (1982) that anthralin, or the only two known decomposition products, the dimer and the quinone, are weak inhibitors of G6-PDH.…”