Anxiolytic effects of orcinol glucoside and orcinol monohydrate in mice

Context: Anxiety is a common psychological disorder, often occurring in combination with depression, but therapeutic drugs with high efficacy and safety are lacking. Orcinol glucoside (OG) was recently found to have an antidepressive action.

Objective: To study the therapeutic potential of OG and orcinol monohydrate (OM) as anxiolytic agents.

Materials and methods: Anxiolytic effects in mice were measured using the elevated plus-maze, hole-board, and open-field tests. Eight groups of mice were included in each test. Thirty minutes before each test, mice in each group received one oral administration of OG (5, 10, or 20 mg/kg), OM (2.5, 5, or 10 mg/kg), the positive control diazepam (1 or 5 mg/kg), or control vehicle. Each mouse underwent only one test. Uptake of orcinol (5 mg/kg) in the brain was qualitatively detected using the HPLC-MS method.

Results: OG (5, 10, and 20 mg/kg) and OM (2.5 and 5 mg/kg) increased the time spent in open arms and the number of entries into open arms in the elevated plus-maze test. OG (5 and 10 mg/kg) and OM (2.5 and 5 mg/kg) increased the number of head-dips in the hole-board test. At all tested doses, OG and OM did not significantly affect the locomotion of mice in the open-field test. Orcinol could be detected in the mouse brain homogenates 30 min after oral OM administration, having confirmed that OM is centrally active.

Discussion and conclusion: The results demonstrated that OG and OM are anxiolytic agents without sedative effects, indicating their therapeutic potential for anxiety.

Anxiety; elevated plus-maze test; hole-board test; natural phenol.