Assessment of analgesic properties of alcohol and aqueous extracts of Opuntia ficus-indica flowers

The cactus (Opuntia ficus-indica (L.) Mill.) belongs to the Cactaceae family and it’s used in traditional folk medicine in treating a number of diseases and conditions. Due to the remarkable biological activity and to the bioactive (phytochemicals) compounds of O. ficus-indica, it becomes the aim of many research studies. The current study aimed to evaluate the analgesic activity of various solvent fractions (aqueous and ethanol) prepared from the O. ficus-indica flowers. The centrally analgesic potential was evaluated using tail flick latency in tail immersion and hot plate methods in mice. Morphine was used as a positive control at a dose of 3 mg kg-1, s.c.. Intra-peritoneal administration of the aqueous extract of O. ficus-indica flowers at the highest dose did not produce any toxicity symptoms, thus the median lethal dose (LD50) was estimated to be greater than 2,500 mg kg-1. The results of the pain behavior evaluation according to the gender approach of mice showed that the pain tolerance threshold is high in males compared to females. We found that various plant extracts at doses of 300, 500, and 1,000 mg kg-1 i.p., displayed significant and dose-dependent protective effects (p < 0.01, p < 0.001, and p < 0.0001) as measured by increased latency time compared to vehicle control. The maximum anti-nociceptive effect was with the ethanol extract (71%) at 60 minutes at a dose of 1,000 mg kg-1, which was equivalent to the effect of morphine (70%). The results suggested that O. ficus-indica might possess significant analgesic effects, supporting the use of this plant in traditional medicine.