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.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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4-Hydroxyphenylpyruvate Dioxygenase / drug effects
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Anti-Bacterial Agents
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Anti-Infective Agents / chemistry
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Anti-Infective Agents / isolation & purification*
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Anti-Infective Agents / pharmacology
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Chalcones / chemistry
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Chalcones / isolation & purification
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Chalcones / pharmacology
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Drug Resistance, Bacterial / drug effects
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Enterococcus faecalis / drug effects
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Escherichia coli / drug effects
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Gas Chromatography-Mass Spectrometry
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Gram-Positive Bacteria
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Herbicides
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Ketones / analysis
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Leptospermum / chemistry*
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Methicillin-Resistant Staphylococcus aureus / drug effects
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Microbial Sensitivity Tests
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Molecular Structure
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New Zealand
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Nuclear Magnetic Resonance, Biomolecular
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Phenylpyruvic Acids
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Phloroglucinol* / analogs & derivatives
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Phloroglucinol* / chemistry
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Phloroglucinol* / isolation & purification
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Phloroglucinol* / pharmacology
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Plant Leaves / chemistry
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Vancomycin / pharmacology
Substances
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Anti-Bacterial Agents
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Anti-Infective Agents
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Chalcones
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Herbicides
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Ketones
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Phenylpyruvic Acids
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myrigalone A
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4-hydroxyphenylpyruvic acid
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Vancomycin
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Phloroglucinol
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4-Hydroxyphenylpyruvate Dioxygenase