Context: Despite the many biological activities reported for essential oils, their anti-inflammatory ability is relatively underexplored considering the wide variation in plant sources and in their volatile composition. Oils from Syzygium cumini Skells (SC) and Psidium guajava L. (PG) (Myrtaceae) have been described as having diverse pharmacological activities.
Objective: The current study seeks to evaluate the anti-inflammatory activity of the essential oils from the leaves of SC and PG, as well as some of their terpene-enriched fractions (+V = more volatile and -V = less volatile) obtained by vacuum distillation. Both the pharmacological responses and chemical compositions were correlated.
Materials and methods: The relative contents of the oils and their fractions were evaluated by gas chromatography. Individual constituents in the oils were characterized by gas chromatography coupled to mass spectrometry. Anti-inflammatory activity was accessed in the lipopolysaccharide-induced pleurisy model, by measuring the inhibition of total leukocyte, neutrophil and eosinophil migration in the mice pleural lavage, after oil treatment with the oils at 100 mg/kg.
Results: Eosinophil migration was inhibited by SC (67%), SC (+V) (63%), PG (76%), PG (+V) (67%) and PG (-V) (74%). This efficacy was correlated with the presence of β-pinene and β-caryophyllene in the oils, a result that was reinforced by evaluating both these pure components (38 and 50% inhibition, respectively). Synergistic effects associated with the presence of α-pinene were speculated.
Discussion and conclusion: Essential oils from SC and PG may be useful to treat inflammatory diseases by mechanisms that include the inhibition of eosinophil migration.