Background: The search for natural inhibitors of snake venom toxins is essential to
supplement or even replace the serum therapy. The aim of this work was to evaluate the pharmacological
properties of essential oil from Lippia origanoides Kunth. (Verbenaceae).
Methods: The oil was extracted by hydrodistillation and the constituents were identified and
quantified by GC-MS and GC-FID. The essential oil from L. origanoides was evaluated in hemolysis
tests, on the activities of phospholipases A2 and serine proteases and in coagulation and
thrombolysis induced by different snake venoms.
Results: The major constituents of essential oil were carvacrol, p-cymene, γ-terpinene, and thymol.
The oil inhibited approximately 10 % of the phospholipase A2 activity induced by Bothrops
atrox, Bothrops jararaca, Bothrops jararacussu and Bothrops moojeni venoms and was not cytotoxic
against erythrocytes. However, previous incubation of the oil with B. jararacussu, B. moojeni,
and Crotalus durissus terrificus (C.d.t.) venoms resulted in potentiation of hemolytic activity
(30 % and 50 % for 0.6 µL mL-1 and 1.2 µL mL-1, respectively). The essential oil presented a procoagulant
effect on human citrated plasma, potentiated the thrombolytic action of proteases and
phospholipases A2 present in B. jararacussu venom, and serine protease activity induced by B.
jararaca and Lachesis muta venoms. When pre-incubated with the C.d.t. venom, however, prothrombotic
activity was observed.
Conclusion: The results obtained in this work amplify the pharmacological characterization of
the essential oil from L. origanoides. However, new studies are fundamental to define the action
mechanisms and determine pharmaceutical applications.