Dicranin, an antimicrobial and 15-lipoxygenase inhibitor from the moss Dicranum scoparium

Extracts of nine mosses, collected in Switzerland, were screened for antimicrobial, antioxidative, and 15-lipoxygenase (15-lpo) inhibitory activities. The CH2Cl2 extract of Dicranum scoparium was found to possess pronounced antimicrobial activity against Bacillus cereus, Bacillus stearothermophilus, Bacillus subtilis, Staphylococcus aureus, and Escherichia coli. In addition, inhibition of soybean 15-lpo occurred at very low concentration. Phytochemical investigation of this extract afforded Z,Z,Z-octadeca-6-yne-9,12,15-trienoic acid [1] by a combination of chromatographic techniques. This compound, named dicranin [1], was found to be responsible for most of the biological activity. The strongest antimicrobial effect was observed against Streptococcus faecalis (disc diffusion assay). In contrast to the CH2Cl2 extract of D. scoparium, dicranin was inactive against E. coli. Dicranin was identified by ir, ms, and nmr spectroscopy. A 2D INADEQUATE experiment confirmed the structure and yielded the assignment of all 13C-nmr signals.