Variation in essential oil components and anti-inflammatory activity of Allophylus edulis leaves collected in central-western Brazil

Ethnopharmacological relevance: An infusion obtained from the leaves of "chal-chal" (Allophylus edulis Radlk.) is used for popular treatment of intestinal disorders and as an anti-inflammatory throat treatment. Because of the anti-inflammatory medicinal folk use, a previous work reported scientific research confirming the anti-inflammatory activity of A. edulis essential oil collected in Dourados, MS, Brazil, in March 2015.

Aim of the study: The aim of this study was to evaluate the variation in the chemical profile of the essential oil of A. edulis plants collected in Dourados (EOAE-D) and Bonito (EOAE-B), two cities in Mato Grosso do Sul State, Brazil. Additionally, we evaluated the anti-inflammatory effects of the essential oil, as well as that of the major compounds (caryophyllene oxide and α-zingiberene), in experimental in vivo models of inflammation in mice.

Materials and methods: Leaves were collected from plants at both sites in July 2018. The composition of the essential oil (EOAE-D and EOAE-B) was determined by GC/MS, and major compounds (caryophyllene oxide and α-zingiberene) were isolated and identified by chromatographic methods and NMR spectroscopy. Anti-inflammatory capacities were assessed using two classical models of inflammatory models, carrageenan- and CFA-induced paw inflammation (mechanical and thermal hyperalgesia).

Results: Both EOAE-D and EOAE-B showed sesquiterpenes as a major constituent, namely, caryophyllene oxide (29.5%) and α-zingiberene (45.0%), respectively. In tests, EOAE, caryophyllene oxide and α-zingiberene-induced antiedematogenic and antihyperalgesic effects were found in the different utilized models.

Conclusions: The results indicate that samples from the two cities differed in chemical composition but not in their anti-inflammatory and antihyperalgesic effects. This finding corroborates the use of A. edulis as a medicinal plant and indicates its potential in the therapy of inflammatory conditions.

Keywords: Sapindaceae; carrageenan; chal-chal; complete Freund’s adjuvant; essential oil; sesquiterpenes.