AIM OF THE STUDY: The purpose of this study was to determine the anti-inflammatory activity of the ethanol extract of E. maculata resin exudate, its methylene chloride and n-butanol fractions, as well as the isolated compounds.

MATERIALS AND METHODS: the ethanol extract was partitioned by methylene chloride, and n-butanol saturated with water. The fractions were chromatographed to isolate pure compounds. In-vivo anti-inflammatory activity of the ethanol extract, the fractions at a dose of 200 mg/kg, and the isolated compounds (20 mg/kg) was estimated using carrageenan-induced rat paws edema method against indomethacin (20 mg/kg). The activity was supported by histopathological and biochemical parameters.

RESULTS: Three isolated compounds were identified as aromadendrin (C1), 7-O-methyl aromadendrin (C2), and naringenin (C3). Our findings demonstrated that the tested fractions significantly reduced the paw edema starting from the 3rd to the 5th hour as compared to the positive control, compounds C2 and C3 showed the greatest significant reduction in paw edema. The ethanol extract, fractions, C2, and C3 demonstrated an anti-inflammatory potential through reducing the levels of TNF-α, IL-6, and PGE2, as well as COX-2 protein expression compared to the negative control. These results were supported by molecular docking, which revealed that the isolated compounds had high affinity to target COX-1 and COX-2 active sites with docking scores ranging from -7.3 to -9.6 kcal mol-1 when compared to ibubrofen (-7.8 and -7.4 kcal mol-1, respectively). Molecular dynamics simulations were also performed and confirmed the docking results.