4.8. Anti-Inflammatory Activity: Carrageenan-Induced Paw Edema

Anti-inflammation activity of the essential oils was determined on Carrageenan-induced paw edema in Sprague Dawley rats, following Amdekar et al. (2012) [37,38]. Female Sprague Dawley rats (180–250 g) were divided into nine groups of five animals per group. In all groups, 0.1 mL, 1% w/v λ-carrageenan analytical grade (Sigma-Aldrich Chemie Gmbh., Munich, Germany) in normal saline was injected into the subplantar tissue of the right hind paw. Plant essential oils, obtained from rhizomes and leaves, were dissolved separately in 2.5% DMSO (final volume 50 µL) and applied on the right hind paw of rats from the test groups, in concentrations of 10%, 20% or 40%. Oil was applied twice: first, immediately after the carrageenan injection, and again 3 hours later. The same volume (50 µL) of DMSO was applied to the right paw of animals from the control group. Paw thickness was measured before the carrageenan injection and 1, 2, 4 and 6 h after, using a digital caliper.

Edema thickness (mm) represents increases in the paw thickness at different time intervals after the carrageenan injection, relative to the values obtained before injection. Anti-inflammatory activity (edema inhibition) was calculated as anti-inflammatory activity (%) = (C–T)/(C) ×100, where C represents edema thickness in the control group, and T is the edema thickness in the test group. Indomethacin (10 mg/kg, p.o.) dissolved in saline was used as a standard anti-inflammatory drug, and its anti-inflammatory activity was measured as compared with the control group of animals that received the same amount of normal saline. Indomethacin and saline were given orally, 1 h before the carrageenan was injected. Data is expressed as mean ± S.D. The data was subjected to one–way analysis of variance (ANOVA) followed by Dunnett’s test. Differences between two means were detected by Student t-test. Data were considered significantly different for p < 0.05.