Abstract
The first triketone-phloroglucinol-monoterpene hybrids, callistrilones A and B (1 and 2), along with a postulated biosynthetic intermediate (3) were isolated from the leaves of Callistemon rigidus. Compounds 1 and 2 featured a new carbon skeleton with an unprecedented [1]benzofuro[2,3-a]xanthene or [1]benzofuro[3,2-b]xanthene pentacyclic ring system composed of three kinds of building blocks. Their structures and absolute configurations were elucidated by spectroscopic analysis, X-ray diffraction, and electronic circular dichroism (ECD) calculations. A plausible biogenetic pathway for the new compounds is also proposed. Compound 1 exhibited moderate antibacterial activity against Gram-positive bacteria including multiresistant strains.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Anti-Bacterial Agents / chemistry
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Anti-Bacterial Agents / isolation & purification*
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Anti-Bacterial Agents / pharmacology
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Circular Dichroism
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Enterococcus faecium / drug effects
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Gram-Positive Bacteria / drug effects
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Microbial Sensitivity Tests
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Molecular Structure
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Monoterpenes / chemistry
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Monoterpenes / isolation & purification*
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Monoterpenes / pharmacology
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Myrtaceae / chemistry
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Nuclear Magnetic Resonance, Biomolecular
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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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Staphylococcus aureus / drug effects
Substances
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Anti-Bacterial Agents
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Monoterpenes
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callistrilone A
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callistrilone B
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Phloroglucinol