The Study of Anti-Inflammatory Activity of Oil-Based Dill (Anethum graveolens L.) Extract Used Topically in Formalin-Induced Inflammation Male Rat Paw

Inflammation is one of the symptoms of many common and harmful diseases. As it is incurable through chemical drugs, the study on this ailment using new methods and drugs seems necessary. In addition, the adverse effects of the present anti-inflammatory drugs like NSAIDS and Glucocorticoid appeared in the long time use make such study more demanded. Accordingly, in this study we examined the effects of aerial organs' extract and seed of a plant commonly used in Iranian traditional medicine named Dill on the inflammation caused by plantar injection of formalin in rats and compared them with Diclofenac-gel. One of the methods used for the inflammation assessment is injecting formalin in the rat paw and then measuring the paw volume by the new plethysmometer (weighing method). The assessment is done at a specific time on day for 8 days and then recorded. This study includes 3 groups of 6 male rats: Formalin, Dill-Oil and Diclofenac-gel groups. The Dill-Oil group received 2 g of Dill-Oil, containing 100 mg Dill-extract and the Diclofenac group received 2 g gel containing, 20 mg Diclofenac Na. Data were analyzed with SPSS 17 using ANOVA, Kruskal-Wallis, and Repeated-Measures. The average paw volumes changes in these groups after Formalin-induced inflammation on 1st day, were 0.31 (standard error (SEM) = 0.02), 0.30 (SEM = 0.01) and 0.32 (SEM = 0.05) respectively, with no significant difference. Regarding the peak of inflammation on the 2nd day, it was indicated that the average inflammations in Formalin, Dill-Oil and Diclofenac-gel groups were 0.44 (SEM = 0.03), 0.15 (SEM = 0.04) and 0.36 (SEM = 0.08), respectively. The paw volume changes in groups receiving Dill-oil and Diclofenac-gel, after the daily formalin injection in 8 days compared to the blank group, had a significant decrease (p < 0.001). The Dill group showed even more decrease in the paw volume compared to the Diclofenac one. The results of paw volume measurement analyzed by the Plethysmometer manifest that the Dill-Oil is able to decrease the paw volume significantly.