[Effect of phototoxic substances on simple biological systems. I. Standardizing the method with furocoumarins]

As a basis for the investigation of new substances in respect of their photosensitization effects, we established and standardized 3 microbiological test systems, which enabled us to do without animal experiments. Using several furocumarines and various sources of light, we performed a comparative study on the eukaryotes, Chlamydomonas reinhardii (CR) and Candida albicans, and the prokaryote, Bacillus subtilis. We found that, if different light qualities were employed, our test systems also allowed a comparison of different substances by means of half-quantitative evaluation of the inhibiting areolas, which appear after exposure. With regard to the furocumarines, 8- and 5-methoxypsoralene (MOP) had the strongest photosensitizing effect under all test conditions. The remaining furocumarines showed decreasing effectiveness from psoralene to trimethylpsoralene (TMP) and imperatorine; psoralene, however, was slightly more effective in CR than 5-MOP. With the exception of CR, TMP had a stronger effect on the micro-organisms than imperatorine.

[Allergic contact eczema to ninhydrin]

Use of a surgical marking pen to indicate test areas on the skin during epicutaneous evaluation caused eczema in three female patients undergoing patch testing. Close scrutiny of the individual components of this surgical marking pen revealed contact dermatitis to ninhydrine, a substance whose allergenic potential has hardly been noted in the relevant literature.