Antiinflammatory Activity of Flavonoids:Mouse Ear Edema Inhibition

In this inverstigation, the various flavonoid aglycones were evaluated for their inhibitory activities against croton-oil or arachidonic acid induced mouse ear edema by oral or topical administration. The compounds tested were thirteen derivatives of flavan-3-ol(catechin and epicatechin), flavanone (flavanone and naringenin), flavone (flavone, chrysin and apigenin), flavonol(favonol, galangin, quercetin and morin) and isoflavone (biochanin A and 2-carbethoxy-5,7-dihydroxy-4'-methoxyisoflavone), along with hydrocortisone, indomethacin, 4-bormophenacyl bromide, nordihydroguaiaretic acid and phenidone as positive controls. A(isoflavone) were found to show broad inhibitoty activities (14-52%) against croton-oil or arachidonic acid induced ear edema by oral or topical application at the dose of 2 mg/mouse, although they showed less activity than hydrocortisone (26-88%) or indomethacin (36-80%). Flavonoid agtlycones tested showed higher activity when aplied topically than by the oral administration. It was also found that they inhibited arachidonic acid induced edema more profoundly than croton-oil induced edema by topical application. In arachidonic acid induced edema when applied topically, flavone derivatives such as flavone, chrysin and apigenin were revealed to be the good inhibitory agents in addition to flavonols and isoflavones. When quercetin and biochanin. A were selected for evaluating in carrageenan induced rat pleurisy and biochanin both flavonoids showed antiinflammatory activity at the dose of 70 mg/kg by the oral adminis-tration. All of these results revealed that flavonoid aglycones, especially 5,7-dihydroxy-flavonols having hydroxyl group(s) in B-ring and biochanin A (isoflavone) possessed in vivo antiinflammatory activity.