Protein kinase inhibitors from the endophytic fungus stemphylium globuliferum

A. Debbab, R. Ebel, R.A. Edrada-Ebel, V. Wray, M.H.G. Kubbutat, P. Proksch

Research output: Contribution to journalConference Contributionpeer-review


The endophytic fungus Stemphylium globuliferum was isolated from stem tissues of the Moroccan medicinal plant Mentha pulegium. Extracts of the fungus, which was grown on solid rice medium, exhibited considerable cytotoxicity when tested in vitro against L5178Y cells. Chemical investigation yielded eight new secondary metabolites, alterporriol F, alterporriol G and its atropisomer H, alterporriol I and its atropisomer J, altersolanol K, altersolanol L and stemphypyrone, beside eight known compounds. The structures were determined on the basis of one- and two-dimensional NMR spectroscopy and mass spectrometry. Among the alterporriol-type anthranoid dimers, the mixture of alterporriols G and H exhibited considerable cytotoxicity against L5178Y cells with an EC50 value of 2.7 µg/mL, whereas the other congeners showed only modest activity. The compounds were also tested for protein kinase inhibitory activity in an assay involving 24 different kinases. Compounds methylalaternin, macrosporin, altersolanol A and the mixture of alterporriol G and H were the most potent and also selective inhibitors, displaying EC50 values between 0.64 and 1.4 µg/mL toward individual kinases.
Original languageEnglish
Pages (from-to)884-884
Number of pages0
JournalPlanta Medica
Issue number9
Publication statusPublished - Jul 2009


  • endophytic fungus
  • stemphylium globuliferum
  • isolated
  • stem tissues
  • moroccan medicinal plant
  • mentha pulegium
  • cytotoxicity


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