Molecules (May 2023)

The Effects of 1-<i>O</i>-Acetylbritannilactone Isolated from <i>Inula britannica</i> Flowers on Human Neutrophil Elastase and Inflammation of RAW 264.7 Cells and Zebrafish Larvae

  • Ik Soo Lee,
  • Yu-Ri Lee,
  • Jea Heon Sim,
  • Ki Mo Kim,
  • Young Sook Kim

DOI
https://doi.org/10.3390/molecules28114320
Journal volume & issue
Vol. 28, no. 11
p. 4320

Abstract

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During a search for natural inflammatory inhibitors, 1-O-acetylbritannilactone (ABL), a sesquiterpene lactone, was isolated from the flowers of Inula britannica. ABL significantly inhibited human neutrophil elastase (HNE) with a half-maximal inhibitory concentration (IC50) of 3.2 ± 0.3 µM, thus did so more effectively than the positive control material (epigallocatechin gallate) (IC50 7.2 ± 0.5 µM). An enzyme kinetic study was performed. ABL noncompetitively inhibited HNE with an inhibition constant Ki of 2.4 µM. ABL inhibited lipopolysaccharide-induced nitric oxide and prostaglandin E2 production by RAW 264.7 cells in a dose-dependent manner, as well as the protein-level expression of inducible nitric oxide synthase and cyclooxygenase-2. The anti-inflammatory effect of ABL was confirmed using a transgenic Tg(mpx:EGFP) zebrafish larval model. The exposure of the larvae to ABL inhibited neutrophil recruitment to the site of injury after tail fin amputation.

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