Antinociceptive activity of certain dihydroxy flavones

Four dihydroxy flavone derivatives viz 5,3´-, 7,3´-, 2´,3´- and 2´,4´-dihydroxy flavones were evaluated for their antinociceptive response in doses ranging from 3 to 200 mg/kg (s.c). Antinociception in mice was studied employing acetic acid induced abdominal constrictions, formalin induced nociception and tail immersion assay procedures. Involvement of opioid mechanism in the antinociceptive action of dihydroxy flavones was investigated using naloxone in acetic acid assay. All the four tested dihydroxy flavones exhibited a significant, dose related antinociceptive response in these assay procedures. The inhibition of nociceptive response was more than 98% in acetic acid writhing assay and 100% in the chronic phase of formalin assay. Naloxone almost completely antagonized the antinociceptive response of the four-dihydroxy flavone compounds. In conclusion, all the four investigated dihydroxy flavones exhibited opioid mediated antinociceptive response in mice.