Nigella damascena L. essential oil and its main constituents, damascenine and β-elemene modulate inflammatory response of human neutrophils ex vivo.

Nigella damascena L belongs to Ranunculaceae family and is mentioned in Eastern traditional medicine for the treatment of high temperatures, regulation of menstruation or catarrhal affections. The anti-inflammatory activity of compounds present in the essential oil obtained from seeds of this plant can be found in literature, however no studies on immunomodulatory activity are provided. Hence, in this work anti-inflammatory activity of N. damascena seed essential oil as well as damascenine and main compound β-elemene was evaluated on ex-vivo lipopolysaccharide (LPS)-stimulated human neutrophils. For isolation of damascenine fast and efficient protocol was elaborated using high performance countercurrent chromatography technique for the first time. Also detailed spectroscopic characteristic of damascenine was provided for the first time. Damascenine was separated from the essential oil in a mixture of petroleum ether/acetonitrile/acetone (2:1.5:0.5 v/v/v) in reversed phase mode in 12 min with 99.47% purity. Essential oil, damascenine and β-elemene presented immunomodulatory activity evaluated in LPS-stimulated neutrophils ex vivo. All studied samples significantly inhibited release of interleukin 1 beta (IL-1β) and interleukin 8 (IL-8). What is more, damascenine and β-elemene decreased matrix metallopeptidase 9 (MMP-9) production similar to dexamethasone. The release of tumor necrosis factor (TNF-α) was also inhibited in all range of concentrations, however the activity was weaker then activity of dexametasone. The previously reported anti-inflammatory activity of damascenine and β-elemene investigated in murine models was confirmed in our study on human neuthrophils suggesting their possible strong inhibitory effect on inflammatory response progression.