Bioactive metabolites from the endophytic fungus stemphylium globuliferum isolated from mentha pulegium

Debbab, Adbessamad and Aly, Amal H. and Edrada-Ebel, RuAngelie and Wray, Victor and Muller, Werner E.G. and Totzke, Frank and Zirrgiebel, Ute and Schachtele, Christoph and Kubbutat, Michael H.G. and Lin, Wenhan and Mosaddak, Mahjouba and Hakikj, Adbelhak and Proksch, Peter and Ebel, Rainer (2009) Bioactive metabolites from the endophytic fungus stemphylium globuliferum isolated from mentha pulegium. Journal of Natural Products, 72 (4). pp. 626-631. ISSN 0163-3864

Abstract

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 five new secondary metabolites, alterporriol G (4) and its atropisomer alterporriol H (5), altersolanol K (11), altersolanol L (12), stemphypyrone (13), and the known compounds 6-O-methylalaternin (1), macrosporin (2), altersolanol A (3), alterporriol E (6), alterporriol D (7), alterporriol A (8), alterporriol B (9), and altersolanol J (10). 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 (4/5) 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 kinase inhibitory activity in an assay involving 24 different kinases. Compounds 1, 2, 3, and the mixture of 4 and 5 were the most potent inhibitors, displaying EC50 values between 0.64 and 1.4 μg/mL toward individual kinases.

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