Cycloartanes from Oxyanthus pallidus and derivatives with analgesic activities

CaHReF 2016, Yaoundé Conges hall, 23 – 26 August 2016 , PP24

Laboratory of Animal Physiology and Phytopharmacology, Faculty of Science, University of Dschang

Cycloartanes are secondary metabolites of the class tetracyclic triterpenes, synthesized by many plant species. They have been shown to possess many pharmacological properties including anti-inflammatory and analgesic. Three new cycloartanes named OP3, OP5 and OP6 have been recently isolated from the leaves of Oxyanthus pallidus. The present study aimed at evaluating analgesic and anti-inflammatory properties of these compounds and those of their respective aglycones (AOP1, AOP2 and AOP3) and acetyl (BOP1, BOP2 and BOP3) derivatives administered orally at the doses of 2.5 and 5 mg/kg. Acute antinociceptive properties were evaluated on formalin induced pain in mice while the chronic analgesic and anti-inflammatory of OP5 at the doses of 2.5 and 5mg/kg were tested in rats during 10 days. At the dose of 5 mg/kg, the nine products taken individually, significantly reduced the two phases of the algesia induced by the intraplantar injection of formalin with percentages of inhibition ranging from 57.75 to 78.14 % during the first phase and from 12.56 to 68.22% during the second phase. The OP6 molecule showed the best activity in a constant manner in the two phases. Acid hydrolysis did not significantly affect the antinociceptive activities but acetylation significantly reduced the effects of these compounds on the second phase of pain. The OP5 did not exhibited acute and chronic anti-inflammatory effects in rats. Taking these results together, we can conclude that the cycloartanes OP3, OP5 and OP6 possess acute analgesic properties but lack anti-inflammatory properties. The analgesic effect of these compounds depends at least partially to the hydroxyl group attached to the aglycone while sugars attached to the aglycone do not affect this activity.

Cycloartanes, pain, inflammation