Antinociceptive activity of methanol extract of flowers of Impatiens balsamina

Ethnopharmacological relevance: Impatiens balsamina Linn. (Balsaminaceae), an annual herb locally called Dopati, is cultivated as an ornamental garden plant in Bangladesh. Flowers of the plant are used in folk medicine to treat lumbago, neuralgia, burns and scalds. Aim of the study: This study evaluated the antinociceptive effect of the methanol extract of I. balsamina flowers (MIB). Materials and methods: The extract was evaluated for antinociceptive activity using chemical- and heat-induced pain models such as acetic acid-induced writhing, hot plate, tail immersion and formalin test. To verify the possible involvement of opioid receptor in the central antinociceptive effect of MIB, naloxone was used to antagonize the effect. The effect of MW on central nervous system (CNS) was also studied using hole cross and open field tests. Results: MIB demonstrated strong and dose-dependent antinociceptive activity in all the chemical- and heat-induced mice models (p < 0.05). These findings imply the involvement of both peripheral and central antinociceptive mechanisms. The use of naloxone confirmed the association of opioid receptors in the central antinociceptive effect. MIB also showed significant central nervous system depressant effect (p < 0.05). Conclusion: This study reported the peripheral and central antinociceptive activity of the flowers of I. balsamina and rationalized the traditional use of the flower in the treatment of different painful conditions. (C) 2012 Elsevier Ireland Ltd. All rights reserved.