• M R Sulaiman, Z A Zakaria, H S Chiong, S K Lai, D A Israf, and T M Tg Azam Shah.
• Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Malaysia. shaza8174@yahoo.com
• Med Princ Pract. 2009 Jan 1;18(4):272-9.

ObjectiveThe present study was carried out to explore the antinociceptive as well as the anti-inflammatory effects of an ethanol extract of Stachytarpheta jamaicensis (L.) Vahl (EESJ) using 3 models of nociception and 2 models of inflammation in experimental animals.Materials And MethodsEESJ was prepared by overnight soaking of the oven-dried (50 degrees C; 72 h) ground leaves (500 g) in 80% ethanol (1:5; w/v). The filtrate was evaporated to dryness (50 degrees C), resuspended in distilled water at concentrations to provide the desired doses of 50, 100 and 150 mg/kg. For antinociceptive effects, 3 models were used: acetic acid-induced abdominal writhing, hot-plate- and formalin-induced paw-licking tests; for anti-inflammatory effects, 2 models were used--carrageenan-induced paw edema and cotton-pellet-induced granuloma tests. Appropriate doses were administered intraperitoneally (i.p.) to mice/rats prior to each test. The mechanisms of antinociceptive action of the extract were also investigated by pretreatment with naloxone (5 mg/kg, i.p.).ResultsThe extract exhibited significant (p < 0.05) antinociceptive activity in all nociceptive models tested with dose-dependent activity observed using the abdominal writhing and formalin tests. Pretreatment with naloxone partially, but significantly (p < 0.05) reversed the antinociceptive activity of the extract when assessed using the abdominal-writhing- and formalin-induced paw-licking tests, and completely inhibited its activity when the hot-plate test was used. The extract also showed significant (p < 0.05) anti-inflammatory activity in both the acute (carrageenan-induced paw edema test) and the chronic (cotton-pellet granuloma test) tests.ConclusionThis study showed the potential of EESJ to exert antinociceptive and anti-inflammatory activities, the former being modulated via peripheral and central mechanisms and involving, in part, activation of the opioid receptor system.Copyright (c) 2009 S. Karger AG, Basel.

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