title: Pentacyclic triterpenoids from Embelia schimperi.
abstract: Five oleanane-type pentacyclic triterpenoids were isolated by chromatographic separation of a chloroform extract of the stem bark of Embelia schimperi. Three of these compounds have a methyleneoxy bridge. Two compounds, embelinone and schimperinone, are reported here for the first time from a natural source (they have been synthesized previously during chemical transformations). Their structures were determined by spectroscopic techniques, among which 2-D NMR was useful for complete characterization. Three of the triterpenoids exhibited mild antibacterial properties against the gram-positive bacterial strain Rhodococcus sp.
authors.affiliation: Department of Chemistry, Kenyatta University, PO Box 43844, Nairobi, Kenya.
authors.forename: Alex K
authors.initials: AK
authors.lastname: Machocho
authors.forename: Paul C
authors.initials: PC
authors.lastname: Kiprono
authors.forename: Sarina
authors.initials: S
authors.lastname: Grinberg
authors.forename: Shmuel
authors.initials: S
authors.lastname: Bittner
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D031645:Embelia / Q000737:chemistry*; D006576:Heterocyclic Compounds, 4 or More Rings / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D006572:Heterocyclic Compounds, Bridged-Ring / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D007630:Kenya; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D024301:Plant Bark / Q000737:chemistry; D010946:Plants, Medicinal / Q000737:chemistry; D012240:Rhodococcus / Q000187:drug effects*; D014315:Triterpenes / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D006576:Heterocyclic Compounds, 4 or More Rings; D006572:Heterocyclic Compounds, Bridged-Ring; D014315:Triterpenes