Nortriketones: Antimicrobial Trimethylated Acylphloroglucinols from Ma̅nuka (Leptospermum scoparium)
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- 作者：Daniel P. Killeen ; Lesley Larsen ; Franck E. Dayan ; Keith C. Gordon ; Nigel B. Perry ; John W. van Klink
- 刊名：Journal of Natural Products
- 出版年：2016
- 出版时间：March 25, 2016
- 年：2016
- 卷：79
- 期：3
- 页码：564-569
- 全文大小：351K
- ISSN：1520-6025
文摘
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.