Anti-asthmatic action of quercetin and rutin in conscious guinea-pigs challenged with aerosolized ovalbumin

The effects of quercetin and rutin on the asthmatic responses were studied in ovalbumin (OA)-sensitized conscious guinea pigs challenged with aerosolized-OA. We measured the specific airway resistance (sRaw) in the double-chambered plethysmograph during the immediate-phase response (IAR) and late-phase response (LAR) at 3 approximately 10 min and 24 hr after OA challenge, respectively. We counted leukocytes in bronchoalveolar lavage fluid (BALF) using Wright's stain, as well as in lung tissue fixed with 10% formalin and stained with H & E stain. Quercetin and rutin (7.5 mg/kg, p.o.) significantly and dose-dependently inhibited both sRaw on IAR (31.60 and 26.44%) and LAR (29.87 and 28.69%) but with less efficacy than dexamethasone (3 mg/kg) and salbutamol (0.3 mg/kg), which inhibited IAR by 36.71 and 69.45%, and LAR by 67.23 and 0%, respectively, Quercetin and rutin (15 mg/kg) also inhibited production of histamine, PLA2, and EPO, and recruitment of leukocytes, particularly neutrophils and eosinophils, during LAR. respectively. Dexamethasone (3 mg/kg) also significantly reduced the recruitment of neutrophils, eosinophils, and lymphocytes in BALF, and salbutamol (0.3 mg/kg) reduced neutrophils and eosinophils with lower activity than dexamethasone. These results indicate that quercetin and rutin may be useful in the treatment of IAR and LAR in asthma via inhibition of histamine release, PLA2, and EPO, and reduced recruitment of neutrophils and eosinophils into the lung.