title: Nortriketones: Antimicrobial Trimethylated Acylphloroglucinols from Ma̅nuka (Leptospermum scoparium).
abstract: Four trimethylated acylphloroglucinols (5-8) have been isolated from ma̅nuka (Leptospermum scoparium) foliage. Apart from myrigalone A (8), which has previously been isolated from European bog myrtle (Myrica gale), these compounds have not been characterized before. The nortriketones are structurally similar to the bioactive tetramethylated β-triketones from ma̅nuka, but have one less ring methyl group. Two oxidized trimethylated compounds, 9 and 10, were also isolated, but these are likely isolation artifacts. When evaluated for antibacterial activity against Gram-positive bacteria, myrigalone A (8) was slightly less potent (MIC 64 μg/mL) than the corresponding tetramethylated compound, grandiflorone (4) (MIC 16-32 μg/mL). Unlike their tetramethylated analogues, the nortriketones were inactive against the herbicide target enzyme p-hydroxyphenylpyruvate dioxygenase. The Raman spectra of leaf oil glands in different ma̅nuka varieties can be used to distinguish plants that contain nortriketones from those that accumulate triketones.
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Killeen
authors.forename: Lesley
authors.initials: L
authors.lastname: Larsen
authors.affiliation: Natural Products Utilization Research Unit, Agricultural Research Service, U.S. Department of Agriculture , University, Mississippi 38677, United States.
authors.forename: Franck E
authors.initials: FE
authors.lastname: Dayan
authors.forename: Keith C
authors.initials: KC
authors.lastname: Gordon
authors.forename: Nigel B
authors.initials: NB
authors.lastname: Perry
authors.forename: John W
authors.initials: JW
authors.lastname: van Klink
mesh_terms: D015111:4-Hydroxyphenylpyruvate Dioxygenase / Q000187:drug effects; D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D047188:Chalcones / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D024881:Drug Resistance, Bacterial / Q000187:drug effects; D013293:Enterococcus faecalis / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects; D008401:Gas Chromatography-Mass Spectrometry; D006094:Gram-Positive Bacteria; D006540:Herbicides; D007659:Ketones / Q000032:analysis; D031649:Leptospermum / Q000737:chemistry*; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D015394:Molecular Structure; D009520:New Zealand; D019906:Nuclear Magnetic Resonance, Biomolecular; D010667:Phenylpyruvic Acids; D010696:Phloroglucinol / Q000031:analogs & derivatives / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D018515:Plant Leaves / Q000737:chemistry; D014640:Vancomycin / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D047188:Chalcones; D006540:Herbicides; D007659:Ketones; D010667:Phenylpyruvic Acids; C571989:myrigalone A; C010590:4-hydroxyphenylpyruvic acid; D014640:Vancomycin; D010696:Phloroglucinol; D015111:4-Hydroxyphenylpyruvate Dioxygenase