Anti-inflammatory and antinociceptive effects of mitragyna speciosa korth methanolic extract

To determine the anti-inflammatory and antinociceptive activities of Mitragyna speciosa Korth methanol extract in rodents. Anti-inflammatory activity was evaluated using carrageenan-induced paw edema and cotton pellet-induced granuloma tests in rats. Antinociceptive activity was measured using the writhing test and the hot plate test in mice, and the formalin test in rats. All drugs and extracts were diluted in dH[2]O and administered through the intraperitoneal route. Results were analyzed using one-way ANOVA followed by Dunnett's test for multiple comparisons among groups. Results showed that intraperitoneal administration of the extract at doses of 100 and 200 mg/kg produced significant dose-dependent activity in all of the nociceptive models evaluated [p<0.05]. With the formalin test, the antinociceptive activity in mice was inhibited only at the highest dose of the extract [200mg/kg]. The study also showed that intraperitoneal administration of the methanol extract of M.speciosa [100 and 200 mg/kg] significantly and dose-dependently suppressed the development of carrageenan-induced rat paw edema [p<0.005]. In the chronic test, however, significant reduction in granulomatous tissue formation in rats was observed only at the highest dose of the methanol extract of M. speciosa [200 mg/kg, p<0.005]. The present study suggests the presence of potent antinociceptive and anti-inflammatory principles in the extract, supporting its folkloric use for the treatment of these conditions

Antinociceptive and anti-inflammatory effects of stachytarpheta jamaicensis [L.] Vahl [Verbenaceae]in experimental animal models

The 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 EESJ was prepared by overnight soaking of the oven-dried [50°C; 72 h] ground leaves [500 g] in 80% ethanol [1:5; w/v]. The filtrate was evaporated to dryness [50°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.]. The 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. This 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