title: Antimicrobial and anti-inflammatory activity of four known and one new triterpenoid from Combretum imberbe (Combretaceae).
abstract: Combretum imberbe is used widely in Africa inter alia for treating bacterial infections. In addition to four known triterpenoids, 1alpha,3beta-dihydroxy-12-oleanen-29-oic (1), 1-hydroxy-12-olean-30-oic acid (2), 3,30-dihydroxyl-12-oleanen-22-one (3), and 1,3,24-trihydroxyl-12-olean-29-oic acid (4), a new pentacyclic triterpenoid (1alpha,23-dihydroxy-12-oleanen-29-oic acid-3beta-O-2,4-di-acetyl-L-rhamnopyranoside) 5 has been isolated through a bioassay-guided procedure from the leaves of Combretum imberbe. The structures of the compounds were elucidated on the basis of 1D and 2D NMR experiments, as well as mass spectrometric data. All compounds isolated had moderate (62 microg/ml) to strong (16 microg/ml) antibacterial activity (MIC values) against Staphylococcus aureus and Escherichia coli, with 1 and 5 being most active. Compounds 1 and 5 also showed very strong inhibition of 3alpha-hydroxysteroid dehydrogenase with an IC(50) of 0.3 microg/ml. Compound 5 indicated a moderate anti-proliferative (GI(50)=16.5 and 13.2 microg/ml) and cytotoxic activity (CC(50)=17.6 micro/ml) against K-562, L-929 and HeLa cell lines, respectively. The results of this study give credence to the ethnomedicinal use of Combretum imberbe and expand our knowledge on the biological activity of its metabolites.
authors.affiliation: Department of Paraclinical Science, Faculty of Veterinary Science, University of Pretoria, Onderstepoort 0110, Pretoria, South Africa.
authors.forename: J E
authors.initials: JE
authors.lastname: Angeh
authors.forename: X
authors.initials: X
authors.lastname: Huang
authors.forename: I
authors.initials: I
authors.lastname: Sattler
authors.forename: G E
authors.initials: GE
authors.lastname: Swan
authors.forename: H
authors.initials: H
authors.lastname: Dahse
authors.forename: A
authors.initials: A
authors.lastname: Härtl
authors.forename: J N
authors.initials: JN
authors.lastname: Eloff
mesh_terms: D045002:3-alpha-Hydroxysteroid Dehydrogenase (B-Specific) / Q000037:antagonists & inhibitors; D000349:Africa; D000890:Anti-Infective Agents / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D000893:Anti-Inflammatory Agents / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D029765:Combretum / Q000737:chemistry*; D004926:Escherichia coli / Q000187:drug effects; D006801:Humans; D020128:Inhibitory Concentration 50; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008826:Microbial Sensitivity Tests; D015394:Molecular Structure; D018515:Plant Leaves / Q000737:chemistry; D010946:Plants, Medicinal / Q000737:chemistry; D013211:Staphylococcus aureus / Q000187:drug effects; D014315:Triterpenes / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*
chemical_list: D000890:Anti-Infective Agents; D000893:Anti-Inflammatory Agents; D000970:Antineoplastic Agents; D014315:Triterpenes; D045002:3-alpha-Hydroxysteroid Dehydrogenase (B-Specific)