5-O-Demethylnobiletin (5-Demethylnobiletin), a polymethoxyflavone isolated from Sideritis tragoriganum, is a direct inhibition of 5-LOX (IC50=0.1 μM), without affecting the expression of COX-2. 5-O-Demethylnobiletin (5-Demethylnobiletin) has anti-inflammatory activity, inhibits leukotriene B (4)(LTB4) formation in rat neutrophils and elastase release in human neutrophils with an IC50 of 0.35 μM.