Searching for extracts with a potential anti-inflammatory activity conducted using in vitro models

Based on ethnomedical and metabolomic knowledge of Asteraceae family species we screened Eupatorium cannabinum L, Inula helenium L. and Helianthus annuus L. on their biological activity in vitro. All plants selected for this screening were rich in sesquiterpene lactones showing antibacterial, immunological and anti-inflammatory properties [1].

The aim of this study was to examine the effect of the extracts on pro-inflammatory functions of stimulated neutrophils such as reactive oxygen species (ROS), interleukin 8 (IL-8), tumor necrosis factor alpha (TNFα) production/release and expression of adhesion molecules CD11b/CD18.

The inhibition of ROS production by neutrophils was determined using luminol- dependent chemiluminescence. The effect on IL-8 and TNFα production by neutrophils was measured by an enzyme-linked immunosorbent assay. The expression of adhesion molecules CD11b on neutrophils was analyzed with flow cytometry.

The ethanolic extracts were shown to modulate lipopolysaccharide (LPS)-triggered production of IL-8 (at 25 – 100 µg/mL) and TNF-α (at 25 – 100 µg/mL). They were also active towards f-MLP induced reactive oxygen species production (at 25 – 100 µg/mL). Moreover, only Eupatorium cannabinum L. extract was also shown to decrease the expression of integrin CD11b. A major sesquiterpene lactone isolated from Eupatorium cannabinum L. – eupatoriopicrin inhibited (IC50 < 1µM) IL-8 and TNF-α release by human neutrophils in response to lipopolysaccharides (LPS). Eupatoriopicrin displayed significant effects against f-MLP-induced reactive oxygen species production at 1µM. The effects of eupatoriopicrin were compared with quercetin and clarithromycin used as a positive control.

Fig. 1

Our observations suggest that Eupatorium cannabinum L. can specifically modulate inflammatory functions of neutrophils. Moreover, eupatoriopicrin may contribute to beneficial health effects and can be the lead compound for further in vivo studies.

[1] Bessada SMF, Barreira JCM, Oliveira MPP. Ind Crops Prod 2015; 76: 604 – 615