Essential oil and its nanoemulsion of Araucaria heterophylla resin: Chemical characterization, anti-inflammatory, and antipyretic activities

Araucaria heterophylla tree has been used in traditional medicine for several purposes. The essential oil (EO) of the resin is poorly studied, and up to our knowledge, the EO of the resin of the Egyptian ecospecies of A. heterophylla was not explored. In this study, the resin EO of A. heterophylla was analyzed via GC-MS. The correlation of the chemical composition of the EO with those reported in other ecospecies of A. heterophylla was evaluated via Principal Components Analysis (PCA). The in vivo inflammation inhibition and antipyretic activities in a carrageenan-induced rat model were evaluated for both crude EO and its nanoemulsion. Thirty-nine compounds were characterized in the EO. Monoterpenes (66.53 %) represented the main components followed by sesquiterpenes (30.85 %). alpha-Pinene (44.88 %), germacrene-D (10.25 %), alpha-copaene (4.72 %) and sabinene (4.44 %) were identified as major constituents of the EO. The PCA analysis showed more correlation of EO of the resin from the present study with that from the leaves of both Egyptian and Australian ecospecies, while it was negatively correlated with the EO from the leaves or resin of the Indian ecospecies. These variations could be ascribed to the environmental, climatic or genetic factors. The EO (100 mg/kg) administration in the rat paw edema and rectal temperature exhibited a significant difference (P < 0.05) by 32 %, compared to indomethacin (39 %). Also, it attenuated the levels of proinflammatory cytokines (TNF)-alpha, IL-6, and IL-1 beta by 201.25, 285.62 and 437.0 pg/ml, respectively. Further, the administration of the higher dose of EO and its emulsion (200 mg/kg) attenuated the levels of inflammatory cytokines, improved paw edema and rectal temperature in rats. While the results showed that the low dose of nanoemulsion (100 mg/kg) was the least effective, our findings shed light toward the potentiality of using either the EO or its nanoemulsion from A. heterophylla as green resources with potent an anti-inflammatory and antipyretic promising medicinal agent.