Anxiety disorders are common worldwide and novel compounds are investigated for anxiolytic effect. A few studies have demonstrated the anxiolytic-like activity of natural and synthetic flavonoids. 5-methoxyflavone, a synthetic flavone derivative, has been reported to exhibit central nervous system depressant (sedative-hypnotic) effect in an earlier study. The present study was designed to investigate whether 5-methoxyflavone possesses anxiolytic-like activity in mice by employing two unconditioned models of anxiety such as elevated plus maze and light-dark box test. The possible role played by GABAergic (GABAA) and serotonergic (5HT1A) systems in the anxiolytic-like effect of 5-methoxyflavone was also investigated in the elevated plus maze test. Molecular docking studies were performed to ascertain the interaction of 5-methoxyflavone with GABAA (α2 subunit-containing) and 5HT1A receptors. 5-methoxyflavone treatment in mice (10, 20 or 40 mg/kg, i.p) increased the number of entries and time spent in the open arms in an elevated plus maze (p < 0.001). In the light-dark box test a significant increase in the time spent in light compartment (p < 0.001) and prolonged latency to enter the dark compartment (p < 0.01) were also observed. Pretreatment of mice with 5HT1A antagonist pindolol (10 mg/kg, i.p) or GABAA antagonist bicuculline (2 mg/kg, i.p) significantly attenuated the effect of 5-methoxyflavone in the elevated plus maze test. In silico studies provided evidences for good binding affinity of 5-methoxyflavone towards GABAA (α2 subunit-containing) and serotonergic (5HT1A) receptors by H-bond interactions. In conclusion, the present study identified a novel anxiolytic-like effect of 5-methoxyflavone involving GABAergic and serotonergic mechanisms.
Keywords: 5-methoxyflavone; Anxiolytic-like activity; Docking; GABA(A) (α(2) subunit-containing) receptor; Serotonergic (5-HT(1A)) receptor.
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