SEARCH

SEARCH BY CITATION

Abstract— The aim of this study was to evaluate the analgesic effect of the methanolic extract from callus culture of Phyllanthus tenellus, P. corcovadensis and P. niruri in several models of pain in mice. The extracts (medium containing 2,4-dichlorophenoxyacetic acid) of P. corcovadensis, P. niruri and P. tenellus (3–90 mg kg−1, i.p.) caused graded inhibition of abdominal constrictions induced by acetic acid (0·6%), with ID50 (i.e. dose that reduced response of control by 50%) values of about 30, 19 and >30 mg kg−1, respectively. The extract of callus of Phyllanthus obtained in indole-3-butyric acid and indole-3-acetic acid media (3–90 mg kg−1, i.p.) caused a similar analgesic effect. In the formalin test, the extract of P. tenellus obtained in indole butyric acid medium (3–100 mg kg−1, i.p.) inhibited only the second phase of formalin-induced pain with an ID50 value of about 100 mg kg−1. Both the indole acetic acid and indole butyric acid methanolic extracts of P. tenellus and P. corcovadensis (10–100 mg kg−1, i.p.) dose-dependently inhibited both phases of formalin-induced pain (ID50 values for the second phase were approx. 100 and 52 mg kg−1, respectively). However, the extract of callus from Phyllanthus failed to affect formalin-induced paw oedema, as well as the response to radiant heat in the tail-flick test. In addition, the analgesic effect of morphine, but not the analgesic effects caused by Phyllanthus callus extract, was fully antagonized by naloxone. Preliminary phytochemical analysis revealed the presence of several compounds having no apparent relationship with alkaloids or flavonoids but showing the presence of phenols. These results indicate that, similar to previous reported data from the extract of P. corcovadensis, the methanolic extracts of callus culture of P. niruri, P. corcovadensis and P. tenellus exhibit potent analgesic properties against neurogenic and inflammatory pain that seem to be unrelated to the activation of opioid mechanisms.