The Peperomia serpens (Piperaceae), popularly known as “carrapatinho”, is an epiphyte and herbaceous liana grown wild on different host trees in the Amazon rainforest. Its leaves are largely used in Brazilian folk medicine to treat
inflammation, pain and asthma. This study investigated the effects of essential oil of P. serpens (EOPs) in standard rodent models of pain and inflammation. The antinociceptive activity was evaluated using chemical (acetic acid and
formalin) and thermal (hot plate) models of nociception in mice whereas the anti-inflammatory activity was evaluated by carrageenan (Cg) - and dextraninduced
paw edema tests in rats croton oil-induced ear edema, as well as cell migration, rolling and adhesion induced by Cg in mice. Additionally,
phytochemical analysis of the EOPs has been also performed. Chemical composition of the EOPs was analyzed by gas chromatography and mass spectrometry (GC/MS). Twenty five compounds, representing 89.6% of total oil, were identified. (E)-Nerolidol (38.0%), ledol (27.1%), α-humulene (11.5%), (E)- caryophyllene (4.0%) and α-eudesmol (2.7%) were found to be the major
constituents of the oil. Oral pretreatment with EOPs (62.5-500 mg/kg) significantly reduced the writhing number, with an ED50 value of 188.8 mg/kg
that was used thereafter in all tests. EOPs had no significant effect on hot plate
test but reduced the licking time in both phases of the formalin test, an effect
that was not significantly altered by naloxone (0.4 mg/kg, s.c.). EOPs inhibited
the edema formation induced by Cg and dextran in rats. In mice, EOPs inhibited
the edema formation by croton oil as well as the leukocyte and neutrophil
migration, the rolling and the adhesion of leukocytes. These data show for the
first time that EOPs has a peripheral antinociceptive effect that seems unrelated
to interaction with the opioid system and a significant anti-inflammatory effect in
acute inflammation models.
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