Evaluation of the anti-inflammatory activity of luteolin in experimental animal models

Luteolin, a flavonoid abundant in plants worldwide, demonstrates a spectrum of biological activities. This study is aimed at evaluating its inhibiting effects on inflammatory responses in vivo. We investigated the anti-inflammatory activity of luteolin in acute and chronic models in mice. We found that oral administration of luteolin (10 and 50 mg/kg) efficiently suppressed paw edema when induced by injecting carrageenan, and a similar tendency was also observed in the cotton pellet granuloma test. In the air pouch test, luteolin markedly reduced the number of infiltrated leukocytes and the elevated level of 6-keto-prostaglandin F1alpha (6-keto-PGF1alpha) in the exudate. The results derived from the whole blood assay for cyclooxygenase (COX) and from the reverse transcription-polymerase chain reaction (RT-PCR) assay indicate that luteolin may be a potent selective inhibitor of cyclooxygenase-2 (COX-2) and that the inhibition is attributable to its down-regulation of the mRNA expression of COX-2 in inflammatory responses.