Analgesic Property of Loranthus Acaciae Studied by Molecular Docking and Biological Assays

Abstract

Manal A. Abbas, Belal O. Al-Najjar, Sahar M. Jaffal.

Loranthus acaciae (Loranthaceae) is a perennial semiparasitic mistletoe. This study investigates the analgesic, antidepressant and anxiolytic effects of this plant. Different animal models were used. Also, chemical composition of the extract was analyzed using LC-MS. In writhing test, 150 and 300 mg/kg of L. acaciae inhibited abdominal cramps by 94.14 % and 94.78 %, respectively compared to 57.95 % inhibition produced by 70 mg/kg indomethacin. In hot-plate but not tail-flick test, 300 mg/kg L. acaciae significantly increased latency time. In formalin test, 300 mg/kg L. acaciae decreased paw-licking and flinching in early and late phases of formalin test by 68.5% and 83.3%, respectively compared to 39.2% and 56.1% inhibition by indomethacin (50 mg/kg). Naloxone and caffeine but not glibenclamide reversed the analgesic action of this plant in late phase while only caffeine reversed its action in early phase. In forced swimming and elevated plus maze tests, no statistically significant difference was found between L. acaciae-treated mice and control group. In open field test, L. acaciae decreased the number of lines crossed and rearing behavior. LC-MS analysis of the methanolic leaf extract identified 17 compounds. Loranthin was the major constituent. Based on the results of molecular docking, the activity of L. acaciae could be due to the binding of lupeol, campesterol & rhoifolin to μ-opioid receptor. This study indicates that the analgesic action of L. acaciae was mediated by interaction with opioid and adenosine receptors. No antidepressant or anxiolytic effects were exerted by L. acaciae.