Antinociceptive and anti-inflammatory effects of the ethanol extract of Alpinia conchigera rhizomes in various animal models

Alpinia conchigera Griff. (Zingiberaceae), locally known to the Malays as lengkuas ranting, is native to Peninsular Malaysia. The Malays traditionally used it to treat infection and rashes, and as a health drink. This study evaluated the analgesic and anti-inflammatory activities of the ethanol extract of A. conchigera rhizomes in mice and rats, respectively. The analgesic activity was elucidated using the acetic acid-induced writhing test, hot plate test, and formalin test, while the anti-inflammatory activity was determined using carrageenan-induced paw edema. The extract (30, 100, and 300 mg/kg) given intraperitoneally (i.p.) exhibited antinociceptive and anti-inflammatory activities in all tests used. The range of percentage of analgesia obtained for all doses of extract in the writhing test was 50-92%, and in the early and late phases of the formalin test was 25-62% and 63-98%, respectively. In addition, naloxone (5 mg/kg) given subcutaneously (s.c.) was found to reverse the extract (300 mg/kg)-induced antinociceptive activity in the writhing, hot plate, and formalin tests. Based on the results obtained, it can be concluded that the ethanol extract of A. conchigera rhizomes possessed a peripheral and central antinociceptive activity that was mediated, in part, via the opioid receptor, as well as anti-inflammatory activity.