Heteromorpha arborescens belongs to the family Apiaceae. It is commonly known as the parsley tree. One of its uses in the Eastern Cape Province of South Africa is for the treatment of abdominal pains. The therapeutic effects of the methanolic and aqueous root extracts of H. arborescens were investigated at two dose levels respectively on experimental models of pain and inflammation in rodents. The antinociceptive activity was evaluated using the hot-plate, abdominal constriction and formalin tests. The anti-inflammatory properties of these extracts were assessed using albumin and carrageenan as phlogistic agents. Both extracts produced significant (P<0.05, P<0.01) inhibition of thermal nociception induced by a hot plate. On chemical nociception induced by intraperitoneal acetic acid and subplantar formalin injection, both extracts significantly (P<0.05, P<0.01) decreased the number of writhing episodes and the licking time in a dose dependent manner. Treatment with the extracts at the same doses produced a significant (P<0.05, P<0.01) pain inhibition of the carrageenan induced inflammatory pain. Similarly, both extracts produced a significant (P<0.05, P<0.01) reduction of edema induced by albumin and carrageenan. These results suggest that both extracts of H. arborescens may act by inhibition of the mediators of inflammation. These findings seem to justify the use of the plant in traditional medicine in the management of pain and inflammation related diseases.
Keywords: Heteromorpha arborescens; formalin; hot plate; inflammatory pain; writhing.