Aniseed (Pimpinella anisum L.) essential oil reduces pro-inflammatory cytokines and stimulates mucus secretion in primary airway bronchial and tracheal epithelial cell lines

Aniseed (Pimpinella anisum L., Apiaceae) is a medicinal and aromatic plant widely cultivated in the Mediterranean area and used in foodstuffs, as ingredient of famous liqueurs, confectionery and bakery products. Its essential oil is one of the most selled on the market and used on an industrial level. In addition, aniseed is exploited as an herbal remedy to threat respiratory disorders. However, little information is available about its effect on respiratory tissues during inflammation. In the present work, we evaluated the anti-inflammatory activity and the effect on mucin secretion of aniseed essential oil in primary airway bronchial and tracheal epithelial cells (HBEpC and HTEpC, respectively) in a model of lung inflammation induced by lypopolysaccharide (LPS). The aniseed essential oil was obtained by hydrodistillation of the fruits from plants cultivated in central Italy, and analysed by gas chromatography-mass spectrometry (GC-MS). HBEpC and HTEpC lines were treated with LPS and then incubated with 0.3% of aniseed essential oil. Levels of pro-inflammatory cytokines, IL-8 and IL-1 beta were assessed by RT/PCR and Western Blot analysis. Muc5ac protein release was determined in culture medium of HBEpC- and HTEpC- LPS-treated lines by Western Blot analysis. Aniseed essential oil showed a very high level of (E)-anethole (97.9%). At non-toxic doses, it significantly decreased the expression levels of IL-1 and IL-8 and increased the Muc5ac secretion in LPS-treated HBEpC and HTEpC lines. These results provide new evidence supporting the ethnobotanical use of aniseed in the treatment of respiratory diseases. In particular, aniseed essential oil showed a significant anti-inflammatory effect on both HBEpC and HTEpC cells together with mucus hypersecretion.