The Antinociceptive Action of Aqueous Extract from <i>Muntingia calabura</i> Leaves: The Role of Opioid Receptors

Abstract

Objective: The present study was carried out to investigate the antinociceptive activity of the aqueous extract of Muntingia calabura (MCAE) leaves and to determine the effect of temperature and the involvement of the opioid receptor on the said activity using the abdominal constriction test (ACT) and hot-plate test (HPT) in mice. Materials and Methods: The extract was prepared by soaking the dried powdered leaves of M. calabura in distilled water (dH₂O) overnight, and the supernatant obtained was considered as a stock solution with 100% concentration. The stock solution was diluted to 1, 5, 10, 50 and 100% and used to determine the antinociceptive activity of MCAE. A further experiment was done with 50% concentration to determine the effect of temperature and naloxone involvement of the opioid receptor system in MCAE antinociceptive activity. Results: At the various concentrations MCAE showed significant antinociceptive activity in both tests. However, the concentration-dependent activity was observed only in the ACT but not in the HPT. The 50% concentration of MCAEs were also stable against the effect of various temperatures as indicated by the presence of activity in both tests. The temperatures (40, 60 and 100°C) also showed an enhanced extract activity only in the HPT. Pre-treatment with naloxone (2 and 10 mg/kg) blocked the extract activity in both tests, indicating the involvement of the opioid receptor system in MCAE antinociceptive activity. Conclusion: Our data indicate that M. calabura leaves possess antinociceptive activity against chemically and thermally induced noxious stimuli. The bioactive compound(s) responsible for its antinociceptive activity is/are heat-stable and work partly via the opioid receptor system.

Antinociceptive and Anti-Inflammatory Effects of <i>Stachytarpheta jamaicensis </i>(L.) Vahl (Verbenaceae)in Experimental Animal Models

“…The hotplate test was shown partly to involve the centrally synthesized prostaglandins or cyclo-oxygenase (COX) [21,22] . Furthermore, the ability of EESJ to affect both peripheral and central antinociceptive mechanisms was confirmed by its positive effects in the hot-plate test [23] and in both phases of the formalin test [24] . In addition, the selective opioid antagonist naloxone was found to partially inhibit the antinociceptive activity of the extract, thus suggesting the involvement, at least in part, of opioid receptors in the extract's antinociceptive activity [23,24] .…”

“…Furthermore, the ability of EESJ to affect both peripheral and central antinociceptive mechanisms was confirmed by its positive effects in the hot-plate test [23] and in both phases of the formalin test [24] . In addition, the selective opioid antagonist naloxone was found to partially inhibit the antinociceptive activity of the extract, thus suggesting the involvement, at least in part, of opioid receptors in the extract's antinociceptive activity [23,24] . The opioid-dependent component of EESJ is suggested to be mediated at both peripheral and central levels based on the ability of naloxone to partially inhibit the activity of the extract in the three antinociceptive models [25,26] .…”

Muntingia calabura: A review of its traditional uses, chemical properties, and pharmacological observations

“…Apart from the medicinal uses, the fruits, which are sometimes eaten fresh, are frequently cooked in tarts or made into jam, while the leaf infusion is drunk as a tea-like beverage (Zakaria et al, 2007e).…”

“…In a subsequent study published in response to the finding reported in 2006, Zakaria et al (2007e) continued to build the antiociceptive profile of AEMC L , collected in Shah Alam, Selangor, Malaysia, between January and February 2004. AEMC L , in the concentrations of 1, 5, 10, 50, and 100% (which is equivalent to the doses of 2.7, 13.5, 27, 135, and 270 mg/kg, respectively), was tested for its antinociceptive activity using the abdominal constriction test and hot plate test.…”

Muntingia calabura

“…The scientists also found that M. calabura leaves possessed antinociceptive activity against chemically and thermally induced noxious stimuli (Zakaria et al 2007a ) . The bioactive compound(s) responsible for its antinociceptive activity was/were heatstable and worked partly via the opioid receptor system.…”