Influence of ultraviolet light, various temperatures, and zinc ions on anthralin (dithranol). Biochemical and chemical investigations.

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.