Immunomodulatory effects of Santolina chamaecyparissus leaf extracts on human neutrophil functions

Santolina chamaecyparissus L. (Asteraceae) is an aromatic plant wide spread in the Mediterranean region. It is used in folk medicine for its anti-inflammatory properties.

The effects of S. chamaecyparissus aqueous extract (SCAE) and polyphenolic extract (SCPE) on human polymorphonuclear neutrophil (PMN) degranulation, chemotaxis, phagocytosis, and microbicidal capacity were examined in vitro.

Aqueous and polyphenolic extracts were prepared from S. chamaecyparissus leaves. The elastase release was used as a marker for measuring PMN degranulation, while chemotaxis was performed using a 48-microwell chemotaxis chamber. The phagocytosis and the microbicidal capacity were evaluated using fresh cultures of Candida albicans.

The treatment of neutrophils with different concentrations (10-200 µg/ml) of SCAE and SCPE caused a significant (p < 0.001) and dose-dependent inhibitory effect on elastase release in fMLP/Cytochalasin B (CB)-stimulated neutrophils. Indeed, 100 µg/ml of SCAE exerted an inhibitory effect of 51.97 ± 6.2%, whereas SCPE at the same concentration abolished completely PMN degranulation. Moreover, both extracts inhibited markedly (p < 0.01) fMLP-induced chemotactic migration. At 200 µg/ml, SCAE and SCPE exerted an inhibitory effect of 54.61 ± 7.3% and 57.71 ± 7.44%, respectively. In addition, a decline in both phagocytosis and microbicidal capacity against Candida albicans was observed when PMNs were exposed to 100 and 200 µg/ml of SCAE or SCPE.

The exerted effects on neutrophil functions support the anti-inflammatory activity and show new mechanisms of action and effectiveness of S. chamaecyparissus leaf extracts. This plant may be considered as an interesting source of anti-inflammatory and immunomodulatory agents.