Anti-inflammatory activity of quercetin and isoquercitrin in experimental murine allergic asthma.

OBJECTIVE

Eosinophils and cytokines are implicated in the pathogenesis of allergic diseases. In the present study, we investigate the anti-inflammatory effect of quercetin and isoquercitrin in a murine model of asthma.

METHODS

BALB/c mice were immunized (ovalbumin/aluminum hydroxide, s. c.), followed by two intranasal ovalbumin challenges. From day 18 to day 22 after the first immunization, the mice received daily gavages of isoquercitrin (15 mg/kg) or quercetin (10 mg/kg). Dexamethasone (1 mg/kg, s. c.) was administered as a positive control. Leucocytes were analyzed in bronchoalveolar lavage fluid (BALF), blood and pulmonary parenchyma at 24 h after the last ovalbumin challenge. Interleukin-5 (IL-5) was analyzed in BALF and lung homogenates.

RESULTS

In animals receiving isoquercitrin or quercetin, eosinophil counts were lower in the BALF, blood and lung parenchyma. Neutrophil counts in blood and IL-5 levels in lung homogenate were lower only in isoquercitrin-treated mice. No alterations in mononuclear cell numbers were observed.

CONCLUSIONS

Quercetin and isoquercitrin are effective eosinophilic inflammation suppressors, suggesting a potential for treating allergies.