title: Antibacterial and antioxidant cassane diterpenoids from Caesalpinia benthamiana.
abstract: Bioactivity-guided fractionation of the light petroleum extract of Caesalpinia benthamiana (=Mezoneuron benthamianum) root bark has led to the isolation of two cassane diterpenoids, designated as benthaminin 1 and 2. A third compound, a deoxy form of caesaldekarin C (also referred to as methyl vouacapenate) which has previously been isolated from Caesalpinia major, C. bonducella, Vouacapoua americana and V. macropetala, was also isolated, together with beta-sitosterol and stigmastenone. The antibacterial and antioxidant activities of these cassane diterpenoids have been assessed using the microdilution assay method and DPPH spectrophotometric and TBA lipid peroxidation assays. Benthaminin 1 was the more active antibacterial compound with MIC values of 47.8 microM for both Staphylococcus aureus and Micrococcus flavus. Benthaminin 2 was the more active antioxidant compound and showed IC50 values of 42.7 microM and 74.2 microM for the DPPH and TBA assays, respectively. Deoxycaesaldekarin C possessed both antibacterial and antioxidant activities. The presence of methyl ester and methyl functional groups as well as an unsaturated furan ring appears to confer antibacterial activity. On the other hand, the relatively stronger antioxidant activity of benthaminin 2 may be associated with the presence of an exocyclic methylene function.
authors.affiliation: Pharmacognosy Research Laboratories, Pharmaceutical Sciences Research Division, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, UK.
authors.forename: Rita A
authors.initials: RA
authors.lastname: Dickson
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Houghton
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Hylands
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D029911:Caesalpinia / Q000737:chemistry*; D004224:Diterpenes / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D016166:Free Radical Scavengers / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D015227:Lipid Peroxidation / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D010936:Plant Extracts / Q000737:chemistry
chemical_list: D000900:Anti-Bacterial Agents; D004224:Diterpenes; D016166:Free Radical Scavengers; D010936:Plant Extracts; C521579:benthaminin 1; C521580:benthaminin 2; C521578:deoxycaesaldekarin C