Antiasthmatic action of dibenzylbutyrolactone lignans from fruits of Forsythia viridissima on asthmatic responses to ovalbumin challenge in conscious guinea-pigs.

It was reported previously that dibenzylbutyrolactone lignans from Forsythia viridissima fruits, which are traditional medicines for the treatment of inflammatory diseases, have antiinflammatory effects. In this study, the effects on the immediate-phase response (IAR) and late-phase response (LAR) following aerosolized-ovalbumin challenge in ovalbumin-sensitized guinea-pigs were evaluated by measuring the specific airway resistance (sRaw), recruitment of leukocytes and chemical mediators in the bronchoalveolar lavage fluids (BALF) as well as a histopathological survey. Arctiin and matairesinol at 12.5 mg/kg significantly (p < 0.05) decreased sRaw by 51.83% and 43.15% in IAR and by 47.41% and 35.43% in LAR, respectively, whereas arctigenin at 25 mg/kg was significantly active, compared with the controls. Furthermore, arctiin and arctigenin dose-dependently inhibited histamine, and the activities of phospholipase A₂ (PLA₂) and eosinophil peroxidase (EPO) in BALF, respectively, whereas matairesinol inhibited EPO and PLA₂ at 12.5 mg/kg and histamine at 50 mg/kg, in addition, they moderately improved the infiltration of eosinophils, compared with controls. Dexamethasone, cromolyn and salbutamol significantly inhibited sRaw in both IAR and LAR, and the recruitment of leukocytes and chemical mediators, whereas salbutamol did not alter chemical mediators, in BALF. These results indicate the three lignans have antiasthmatic effects which were less active than those of the reference drugs.