The sensitizing capacity of naturally occurring quinones. Experimental studies in guinea pigs. I. Naphthoquinones and related compounds.

Experimental studies on the sensitization capacity of naturally occurring naphthoquinones derived from plants and woods have been carried out with 6 compounds. With 4 of these substances (desoxylapachol, menadione, lapachenole andmacassar quinone) guinea pigs could be sensitized. Desoxylapachol, sensitizer from teak wood, and lapachenole, sensitizer from perobawood proved to be the most effective ones. Experiments with macassar quinone (oxidation product of a naphthalene constituent of macassar ebony) still demonstrate that even ortho-naphthoquinones are capable to induce contact allergy. Allergic cross reactions could be obtained with 9 out of 14 different napthoquinones. In animals sensitized with desoxylapachol menadione and lapachol showed the strongest eliciting effect. Furthermore the study demonstrated that the sensitizing effect of naphthoquinones depends on the length and position of the side chain attached to the quinoid ring as well as on the substitution of the carbon atom adjacent to the side chain bearing C-atom. With compounds substituted at this C-atom (e.g. position 3 of lapachol or didimethylallylnaphthoquinone) sensitization could not be obtained.