['Esculetin (6,7-dihydroxycoumarin) is a natural coumarin with anti-oxidant, anti-inflammatory and anti-nociceptive activity. It acts as a potent inhibitor of lipoxygenases (5-LOX and 12-LOX) and decreases the production of matrix metalloproteinases (MMP-1, MMP-3 and MMP-9). Because both inhibition of lipoxygenases and inhibition of matrix metalloproteinases are effective strategies in the treatment of rheumatoid arthritis, we investigated whether esculetin may be effective in adjuvant-induced arthritis in rats.', 'The study was performed on male Lewis rats, in the adjuvant-induced arthritis model. Rats were divided into two groups: control (treated with 1% methylcellulose) and experimental (treated with esculetin - 10 mg/kg ip.). The tested compound was administered for 5 consecutive days starting on the 21', 'The LTB4 level in plasma of rats with adjuvant-induced arthritis is increased in comparison to rats without inflammation (362 ±34 vs. 274 ±15 pg/ml, '] Does esculetin reduce leukotriene B4 level in plasma of rats with adjuvant-induced arthritis?