Abstract
Xanthium spinosum L (Asteraceae) is a medicinal weed distributed worldwide. Many of its diverse ethnopharmacological uses - namely diarrhoea, inflammation, liver disorders, snake bite and fever - are linked - at least in part - to an uncontrolled release of arachidonic acid metabolites. The crude extract of X. spinosum roots from Jordanian origin dose-dependently inhibited the 5-LOX (IC50 congruent to 10 mu g/mL), COX-1 (IC50 congruent to 50 mu g/mL), and 12-LOX (IC50 congruent to 170 mu g/mL) enzymatic pathways in intact pro-inflammatory cells. A direct activity at the level of PLA(2) is not probable, but the extract induced the synthesis of the anti-inflammatory eicosanoid 15(S)-HETE, which may in turn inhibit this enzyme. 5-LOX bioguided fractionation of the crude extract led to the isolation of ziniolide, a known 12,8-guaianolide sesquiterpene lactone, from the hydroalcoholic fraction of the n-hexane extract (IC50 = 69 mu M). Both the plant extract and ziniolide are in vitro inhibitors of the phorbol-induced NF kappa B activation, a key regulator of the arachidonic pathway. (C) 2013 Elsevier B.V. All rights reserved.