Isolation and Characterization of Two New Secondary Metabolites From Quercus incana and Their Antidepressant- and Anxiolytic-Like Potential.

The ethyl acetate fraction of Quercus incana yielded two new compounds [ 1 and 2 ]. The characterization and structure elucidation of these compounds were carried out through various spectroscopic techniques such as mass spectrometry along with one- and two-dimensional NMR techniques. The structural formula was deduced to be 2-(4-hydroxybutan-2-yl)-5-methoxyphenol [ 1 ] and 4-hydroxy-3-(hydroxymethyl) pentanoic acid [ 2 ]. The elevated plus maze (EPM) and light-dark box (LDB) tests (classical mouse models) were performed in order to reveal the anxiolytic potential of both compounds [ 1 and 2 ]. Both compounds displayed dose-dependent increases in open-arm entries and time spent in open arms in EPM (∗ P < 0.05, ∗∗ P < 0.01), and increased the time spent in the lit compartment and increased transitions between the two compartments in LDB test (∗ P < 0.05, ∗∗ P < 0.01). Co-administration of selective benzodiazepine (BZP) receptor antagonist, flumazenil (2.5 mg/kg) with compounds [ 1 and 2 ] decreased the anxiolytic-like activity of both compounds in the EPM indicating BZP-binding site of GABA-A receptors are involved in the anxiolytic-like effect. Similarly, both compounds at the dose level of 10 and 30 mg/kg, i.p. exerted pronounced antidepressant-like effect in both forced swimming as well as tail suspension tests (∗ P < 0.05, ∗∗ P < 0.01; ANOVA followed by Dunnett's post hoc test). The effect at 30 mg/kg was comparable to the reference drug imipramine (60 mg/kg).