Abstract
A pair of racemic indolizidine enantiomers, (±)-homocrepidine A (1), and a piperidine derivative, homocrepidine B (2), were isolated from Dendrobium crepidatum along with the known alkaloid crepidine (3). The racemic mixture of 1 was separated into a pair of enantiomers, (+)-1 and (-)-1, by HPLC using a chiral chromatographic substrate, which represents the first successful example of resolving indolizidine racemic mixtures. The absolute configurations of (+)-1 and (-)-1 were assigned from single-crystal X-ray diffraction data. The evaluation of anti-inflammatory activity with LPS-induced RAW 264.7 macrophages revealed that (+)-1 strongly inhibited the production of nitric oxide (IC50, 3.6 μM) and significantly decreased the expression of inducible nitric oxide synthase, while (-)-1 and (±)-1 only had moderate inhibitory effects (IC50, 22.8 and 14.7 μM). Compound 2 showed moderate anti-inflammatory activity (IC50, 27.6 μM).
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Alkaloids / chemistry
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Alkaloids / isolation & purification*
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Alkaloids / pharmacology*
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Animals
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Anti-Inflammatory Agents, Non-Steroidal / chemistry
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Anti-Inflammatory Agents, Non-Steroidal / isolation & purification*
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Anti-Inflammatory Agents, Non-Steroidal / pharmacology*
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Crystallography, X-Ray
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Dendrobium / chemistry*
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Drugs, Chinese Herbal / chemistry*
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Drugs, Chinese Herbal / isolation & purification
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Drugs, Chinese Herbal / pharmacology*
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Indolizidines / chemistry
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Indolizidines / isolation & purification*
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Indolizidines / pharmacology*
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Inhibitory Concentration 50
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Lipopolysaccharides / pharmacology
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Macrophages / drug effects
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Mice
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Molecular Conformation
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Molecular Structure
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Nitric Oxide / antagonists & inhibitors
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Nitric Oxide / biosynthesis
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Piperidines
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Plant Stems / chemistry
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Stereoisomerism
Substances
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Alkaloids
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Anti-Inflammatory Agents, Non-Steroidal
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Drugs, Chinese Herbal
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Indolizidines
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Lipopolysaccharides
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Piperidines
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homocrepidine A
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homocrepidine B
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Nitric Oxide