Essential oil from Pterodon emarginatus seeds ameliorates experimental autoimmune encephalomyelitis by modulating Th1/Treg cell balance.

Ethnopharmacological Relevance: Pterodon emarginatus Vogel is a medicinal plant commonly used in Brazilian traditional medicine as a folk therapy due to its immunosuppressive, anti-inflammatory, anti-rheumatic, healing, tonic and depurative activities. The essential oil (EO) of Pterodon emarginatus is composed of volatile aromatic terpenes and phenyl propanoids, mainly, β-elemene and β-caryophyllene sesquiterpenes. Here we reported the effects and some underlying mechanisms of action of EO during murine model of MS, the experimental autoimmune encephalomyelitis (EAE).

Materials And Methods: EO (50 and 100 mg/kg) was orally administered during the entire period of development of EAE (preventive treatment, day 0-25). In vitro and in vivo immunological responses were evaluated by ELISA, immunohistochemistry, immunofluorescence and flow cytometry.

Results: We provide evidence that EO of Pterodon emarginatus (100 mg/kg, p.o.) significantly attenuates neurological signs and also the development of EAE. Furthermore, at the same dose EO consistently inhibited Th1 cell-mediated immune response and upregulated Treg response in vitro. Moreover, the EO inhibited both microglial activation and expression of iNOS, associated with inhibition of axonal demyelization and neuronal death during the development of the disease.

Conclusion: This is the first experimental evidence showing that oral administration of EO consistently reduces and limits the severity and development of EAE, mainly, through the modulation of Th1/Treg immune balance, and might represent a helpful new tool for control immunoinflammatory conditions, such as MS.