2.7. Carrageenan-induced paw edema assay

The efficacy of M. cordata in reducing induced inflammation was evaluated by acute inflammation method in rats as designated by Winter et al. (1962). Each type of the test samples was applied on three different groups of rat (n = 5). The basal volume (Co) of the right paw (average volume) of each rat was recorded a plethysmometer (model 7150, UgoBasile, Italy). The control group was administrated orally with 5% Tween 80 (10 mg/kg), while animal from other were given the essential oil and extracts at specified doses. Phenylbutazone (PBZ) (100 mg/kg) was given to each animal of the positive control group. After 30 min, all the animal of each group received 1% carrageenan (0.1 ml) into the sub-planter surface of right hind paw. The volume of the right paw edema was measured at 0 h, 1 h, 2 h, 3 h and 4 h. Inhibitory activity was calculated by the following formula:

where Ct refers to paw size after a specific time interval in hours after carrageenan injection and Co denotes paw size before carrageenan injection.