Aim: To evaluate
in vivo the association of hypericum (
Hypericum perforatum
), valerian (
Valeriana officinalis
) and kava (
Piper methysticum
) with analgesia by assessing their effects in reducing
orofacial pain as well as the possible hepatic, hematologic and biochemical alterations induced by
regular administration of these extracts.
Methods: Orofacial pain was induced in mice with the
administration of 2.5% formalin in the upper lip. After 60 min, the animals were treated with saline,
carbamazepine and hydroalcoholic plant extracts. The nociceptive intensity was determined by
the timing at which the animal remained rubbing the injected area. To assess the hepatotoxic effect,
mice were chronically treated for 25 days with saline, carbamazepine and hydroalcoholic extract.
The animals were euthanized and the liver weighed, followed by a differential count of leukocytes
and measurement of alanine transaminase and alkaline phosphatase.
Results: The evaluation of
analgesic activity in phase 1 reduced the time of rubbing compared to the control by 86% (0.05
mL/10 g) and 76% (0.10 mL/10 g). In phase 2, the extracts reduced rubbing time by 94% and
85%, respectively. In the evaluation of alkaline phosphatase, the groups treated with extracts at
doses of 0.05 mL/10 g and 0.1 mL/10 g increased by 16.1% and 9.5% compared to the control
group and a reduction of 8.5% and 9.1% in the evaluation of alanine transaminase respectively. It
was demonstrated that in the differential counts showed an increase in eosinophils in the treated
group with 0.05 mL/10 g.
Conclusions: The use of hydroalcoholic extract of the associated plants
reduced the orofacial formalin-induced pain with better results than carbamazepine, at both the
neural conductor level of pain (phase 1) and in inflammatory or later pain (phase 2) without presenting
hepatotoxicity. The observed eosinophilia is suggestive of a phenomenon called hormesis.
