AIM: This study aims to evaluate the anti-inflammation an analgesic activity of the aqueous extract of Launaea arborescens (AqELA) and its pathway of action.

METHODS: the investigation of anti-inflammatory and analgesic effects were done using formalin test, acetic acid test. For mechanism investigation, it was used hot plate test to induce opioid receptors, a histamine and serotonin test to induce edema paw, finally, for the TRPV1 receptor, it was used the capsaicin test.

RESULTS: The aqueous extract of Launaea arborescens showed a significant inhibition of abdominal writhing test 95% and 100% inhibition of licking paw using acid acetic test and formalin test respectively (EC: 47 mg/kg and 104 mg/kg). The analgesic effect of the aqueous extract of Launaea arborescens showed inhibition of sensation of pain after 120 min compared to morphine effect. The aqueous extract of Launaea arborescens reduced paw volume after 180 min and 120 min for histamine and serotonin respectively with dose-dependent. Concerning of TRPV1 receptors, the inhibition was showed at doses 100 mg and 300 mg.

MATERIALS AND METHODS: The MEZZ was prepared by macerating oven-dried (50 degrees C) powdered rhizomes (1.2 kg) of Z. zerumbet in 80% methanol in a ratio of 1:20 (w/v) for 48 h. The supernatant was collected, filtered and evaporated to dryness under reduced pressure (50 degrees C) yielding approximately 21.0 g of the crude dried extract. The crude dried extract was stored at -20 degrees C prior to use and was dissolved in normal saline (0.9% NaCl) immediately before administration at concentrations required to produce doses of 25, 50 and 100 mg/kg.

RESULTS: All dosages of MEZZ showed significant (p < 0.05) antiedema activity when assessed using the carrageenan-induced paw edema test and the cotton-pellet-induced granuloma test. The MEZZ exhibited significant (p < 0.05) antinociceptive activity when assessed by the writhing, hot plate and formalin tests. Pretreatment with naloxone (5 mg/kg) significantly decreased the latency of discomfort produced by the 100 mg/kg dose of MEZZ in the hot plate test.