5, 5 and 10 mg/kg of daphnetin, or 25 mg/kg of sulphasalazine orally at 72,48,24, and 2 h before colitis induction, as well as 24 h after induction.
Fraxetin, scoparone and daphnetin and also reduced the incidence of diarrhoea, while the latter two additionally reduced the damage score and colonic weight (Table 1).
The protective effect of esculin was related to potent radical scavenging capacity in the DPPH assay, similar that produced by quercetin, while daphnetin produced potent effects in both the radical scavenging and lipid peroxidation assays (Table 3).
Our results reveal that treatment with esculin, scoparone and daphnetin lead to the strongest improvement in intestinal inflammation, while scopoletin and fraxetin produced discrete effects.
Interestingly, daphnetin and esculin, dihydroxylated coumarins with vicinal diol, produced better effects compared to other coumarin derivatives.
Anti-inflammatory activity of the daphnetin, esculin, scoparone, scopoletin and fraxetin were also related to capacity of counteracting GSH depletion promoted by intestinal inflammatory process.
The intestinal anti-inflammatory activity of daphnetin and esculin was also related to an inhibitory effect on MPO activity.
Daphnetin (7,8-dihydroxy-coumarin) has been recognised as an inhibitor of the proinflammatory lipoxygenase and cyclooxygenase pathways of arachidonate metabolism with strong inhibition of lipid peroxidation and glutathione reductase activity (Fylaktakidou et al.