title: New phloroglucinol derivatives from Hypericum papuanum.
abstract: Bioactivity-guided fractionation of the petroleum ether extract of the aerial parts of Hypericum papuanum led to the isolation of five new tricyclic phloroglucinol derivatives. On the basis of extensive 1D and 2D NMR experiments as well as MS studies, their structures were elucidated as the C-3 epimers of 8-hydroxy-4,4, 7-trimethyl-9-(2-methylpropionyl)-3-(1-methylvinyl)-5beta -H-tricyclo[ 5.3.1.0(1,5)]undec-8-ene-10,11-dione (1,2); the C-3 epimers of 8-hydroxy-4,4, 7-trimethyl-9-(2-methylbutyryl)-3-(1-methylvinyl)-5beta-H-++ +tricyclo[5. 3.1.0(1,5)]undec-8-ene-10,11-dione (3, 4), and 8-hydroxy-4,4, 7-trimethyl-9-(2-methylpropionyl)-5beta-H-tricyclo[5.3 .1.0(1, 5)]undec-8-ene-10,11-dione (5), and their corresponding tautomers (1a, 2a, 3a, 4a, 5a). Compounds 1/1a-5/5a were named ialibinones A-E, respectively. Compounds 1/1a-4/4a showed antibacterial activity against Bacillus cereus, Staphylococcus epidermidis, and Micrococcus luteus.
authors.affiliation: Department of Pharmacy, Swiss Federal Institute of Technology (ETH) Zurich, CH-8057 Zürich, Switzerland.
authors.forename: K
authors.initials: K
authors.lastname: Winkelmann
authors.forename: J
authors.initials: J
authors.lastname: Heilmann
authors.forename: O
authors.initials: O
authors.lastname: Zerbe
authors.forename: T
authors.initials: T
authors.lastname: Rali
authors.forename: O
authors.initials: O
authors.lastname: Sticher
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects; D020902:Hypericum / Q000737:chemistry*; D008826:Microbial Sensitivity Tests; D010696:Phloroglucinol / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D010946:Plants, Medicinal; D013057:Spectrum Analysis
chemical_list: D000900:Anti-Bacterial Agents; D010696:Phloroglucinol