Abstract
Leaves of Ligustrum vulgare (common privet) have been used for
treatment of oropharyngeal inflammations or as antirheumatic, diuretic, and
hypotensive agents in folk medicine in southern Europe. Taking into account
that neutrophils are involved in the inflammation, the aim of the study was
to determine the effect of an aqueous extract prepared from leaves of
Ligustrum vulgare on neutrophil functions. The extract was
characterized by the HPLC-DAD-MSn method. The inhibition of
reactive oxygen species production by formyl-met-leu-phenylalanine- or
phorbol 12-myristate 13-acetate-stimulated neutrophils was determined using
luminol- or lucigenin-dependent chemiluminescence. The effect on
myeloperoxidase, metalloproteinase 9, and interleukin 8 production by
neutrophils was measured by an enzyme-linked immunosorbent assay. Neutrophil
elastase release was established spectrophotometrically. The expression of
adhesion molecules on neutrophils was analyzed with flow cytometry. The main
compounds detected were flavonoids, phenylpropanoids, hydroxycinnamates, and
secoiridoids. The inhibition of oxidative burst by the extract was
comparable in both stimuli models (formyl-met-leu-phenylalanine:
IC50 = 18.2 ± 4.0 µg/mL; phorbol 12-myristate 13-acetate:
IC50 = 19.8 ± 3.0 µg/mL). The extract in the concentration
range of 5–50 µg/mL inhibited neutrophil elastase release by 23.9–34.1 % and
myeloperoxidase release by 24.2–37.4 %. The inhibitory effect on
metalloproteinase 9 and interleukin 8 production was around 20 %. The
extract in the highest concentration modulated the expression of L-selectin
and β
2 integrin. Our results partly support the
traditional use of common privet leaves as an anti-inflammatory agent.
Key words
Ligustrum vulgare L. - Oleaceae - neutrophil oxidative burst - myeloperoxidase - neutrophil elastase - HPLC-DAD-MS
