title: Antibacterial diterpenes from Plectranthus ernstii.
abstract: Three new diterpenoids including two pimaranes (1 and 2) and a labdane (3) were isolated from the whole herb of Plectranthus ernstii. The structures of these compounds were determined as rel-15(zeta),16-epoxy-7alpha-hydroxypimar-8,14-ene (1) and rel-15(zeta),16-epoxy-7-oxopimar-8,14-ene (2), and compound 3 was elucidated as 1R,11S-dihydroxy-8R,13R-epoxylabd-14-ene on the basis of single-crystal X-ray structural analysis. Compound 1 exhibited moderate antistaphylococcal activity against a range of multidrug-resistant (MDR) and methicillin-resistant (MRSA) strains of Staphylococcus aureus with a minimum inhibitory concentration (MIC) of 32 microg/mL. All three diterpenes exhibited antimycobacterial activity against three strains of rapidly growing mycobacteria with MIC values ranging from 8 to 128 microg/mL.
authors.affiliation: Centre for Pharmacognosy and Phytotherapy, The School of Pharmacy, University of London, London, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Stavri
authors.forename: Alan
authors.initials: A
authors.lastname: Paton
authors.forename: Brian W
authors.initials: BW
authors.lastname: Skelton
authors.forename: Simon
authors.initials: S
authors.lastname: Gibbons
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D018360:Crystallography, X-Ray; D004224:Diterpenes / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D018432:Drug Resistance, Multiple / Q000187:drug effects; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D008968:Molecular Conformation; D015394:Molecular Structure; D031346:Plectranthus / Q000737:chemistry*; D013237:Stereoisomerism; D006113:United Kingdom
chemical_list: D000900:Anti-Bacterial Agents; D004224:Diterpenes; C433017:labdane; C542211:rel-15(zeta),16-epoxy-7alpha-hydroxypimar-8,14-ene