Dihydrophenanthrenes and other antifungal stilbenoids from Stemona cf. pierrei.
Three new dihydrophenanthrenes, stemanthrenes A-C, along with the new dihydrostilbene stilbostemin G were isolated and identified from the underground parts of Stemona cf. pierrei together with the known pinosylvin, 4'-methylpinosylvin, dihydropinosylvin, stilbostemins B, D, and E as well as the pyrrolo[1,2-a]azepine alkaloids protostemonine and stemonine. The structures of all new stilbenoids, elucidated by NMR analyses, showed a common substitution pattern for aromatic ring A and characteristic C-methylations for ring B. The trivial name racemosol, previously reported for S. collinsae, was renamed to stemanthrene D due to its priority for another compound. Bioautographic tests on TLC plates with Cladosporium herbarum displayed high antifungal activity for compounds with an unsubstituted aromatic ring A, e.g. pinosylvin, but only weak effects for the higher substituted stilbostemin G and stemanthrenes A-C. Similar results were obtained by germ tube inhibition of five microfungi using 2-fold serial broth dilutions determined by a microplate reader. Because of weak inhibition and chemical instability of stemanthrenes, no EC(50) and EC(90) values could be calculated.
Kostecki
Katharina
K
Comparative and Ecological Phytochemistry Department, Institute of Botany, University of Vienna, Rennweg 14, A-1030, Wien, Austria.
Engelmeier
Doris
D
Pacher
Thomas
T
Hofer
Otmar
O
Vajrodaya
Srunya
S
Greger
Harald
H
D000935:Antifungal Agents / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D001681:Biological Assay; D002855:Chromatography, Thin Layer; D005658:Fungi / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D010616:Phenanthrenes / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D041901:Stemonaceae / Q000737:chemistry*; D013267:Stilbenes / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*
D000935:Antifungal Agents; D010616:Phenanthrenes; D013267:Stilbenes