New sesquiterpene lactones from Arnica tincture prepared from fresh flowerheads of Arnica montana.

Abstract

Investigation of an ethanolic extract prepared from fresh Arnica montana flowers afforded three new 1,5- trans-guaianolides, of which 11alpha,13-dihydro-2-O-tigloylflorilenalin and the respective 2-O-isovaleryl derivative are reported for the first time. Additionally, three new and one known 2beta-ethoxy-2,3-dihydrohelenalin esters were isolated. GC/MS studies of the extract after a two year storage at 4 degrees C demonstrated that the latter were artefacts that had been formed by addition of ethanol to the cyclopentenone structure of helenalin. Formation of these adducts gave compounds possessing an inhibitory activity comparable to that of 11alpha,13-dihydrohelenalin derivatives in the NF-kappaB EMSA and the IL-8 ELISA in vitro assays as well as in the in vivo croton oil-induced mouse ear edema test for one adduct, namely 2beta-ethoxy-6-O-acetyl-2,3-dihydrohelenalin. As expected, 6-O-(2-methylbutyryl)- and 6-O-methacryloyl-helenalin exhibited a stronger activity in the NF-kappaB EMSA and IL-8 ELISA. Sesquiterpene lactones seem to be the most important NF-kappaB inhibiting compounds in the Arnica extract. Bioguided fractionation using the luciferase reporter gene assay resulted in the isolation of only moderately active compounds, such as 6-acetoxy-2,2-dimethylchroman-4-one and 10-acetoxy-8,9-epoxythymol isobutyrate.

• Authors: Olha Kos, Maja T Lindenmeyer, Aurelia Tubaro, Silvio Sosa, Irmgard Merfort
• Journal: Planta medica (Planta Med) Vol. 71 Issue 11 Pg. 1044-52 (Nov 2005) ISSN: 0032-0943 [Print] Germany
• PMID: 16320207 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Anti-Inflammatory Agents
• Lactones
• NF-kappa B p50 Subunit
• NFKB1 protein, human
• Plant Extracts
• Sesquiterpenes, Guaiane

Topics

• Animals
• Anti-Inflammatory Agents (chemistry, pharmacology)
• Arnica (chemistry)
• Flowers (chemistry)
• HeLa Cells
• Humans
• Jurkat Cells
• Lactones (analysis, isolation & purification, pharmacology)
• Male
• Mice
• Molecular Structure
• NF-kappa B p50 Subunit (metabolism)
• Nuclear Magnetic Resonance, Biomolecular
• Plant Extracts (chemistry, pharmacology)
• Sesquiterpenes, Guaiane (chemistry, isolation & purification, pharmacology)