title: Antimicrobial compounds from Eremophila serrulata.
abstract: We report a search for antimicrobial compounds in the Australian plant Eremophila serrulata. Bioassay directed fractionation of a diethyl ether extract prepared from the leaves of E. serrulata led to the isolation of two compounds, an omicron-naphthoquinone, 9-methyl-3-(4-methyl-3-pentenyl)-2,3-dihydronaphtho[1,8-bc]pyran-7,8-dione (2), and a serrulatane diterpenoid, 20-acetoxy-8-hydroxyserrulat-14-en-19-oic acid (3). Two other known serrulatane-type diterpenoids, 8,20-dihydroxyserrulat-14-en-19-oic acid (4) and 8,20-diacetoxyserrulat-14-en-19-oic acid (5) were also isolated. None of these compounds had previously been tested for antimicrobial activity. Compounds 2-5 showed antimicrobial activity against Staphylococcus aureus (ATCC 29213) with minimum inhibitory concentrations (MICs) ranging from 15.6 to 250mug/mL. Compound 2 was the most active with an MIC of 15.6mug/mL and a minimum bactericidal concentration (MBC) of 125mug/mL. This compound also showed antimicrobial activity against other Gram-positive bacteria including Streptococcus pyogenes, and Streptococcus pneumoniae. No activity was observed for this compound against all Gram-negative bacteria tested.
authors.affiliation: Sansom Institute, School of Pharmacy and Medical Sciences, University of South Australia, Frome Road, Adelaide, SA 5000, Australia. Chi.Ndi@postgrads.unisa.edu.au
authors.forename: Chi P
authors.initials: CP
authors.lastname: Ndi
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Semple
authors.forename: Hans J
authors.initials: HJ
authors.lastname: Griesser
authors.forename: Simon M
authors.initials: SM
authors.lastname: Pyke
authors.forename: Mary D
authors.initials: MD
authors.lastname: Barton
mesh_terms: D000890:Anti-Infective Agents / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D004224:Diterpenes / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D041621:Eremophila Plant / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008826:Microbial Sensitivity Tests; D015394:Molecular Structure; D009281:Naphthalenes / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D018515:Plant Leaves / Q000737:chemistry*; D028321:Plant Preparations; D011753:Pyrones / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000187:drug effects*; D013297:Streptococcus pyogenes / Q000187:drug effects*
chemical_list: C524231:8-hydroxyserrulat-14-en-19-oic acid; C525825:9-methyl-3-(4-methyl-3-pentenyl)-2,3-dihydronaphtho(1,8-bc)pyran-7,8-dione; D000890:Anti-Infective Agents; D004224:Diterpenes; D009281:Naphthalenes; D028321:Plant Preparations; D011753:Pyrones