Antianxiety and Antidepressant Activity Guided Isolation and Characterization of Gossypetin from Hibiscus sabdariffa Linn. Calyces

Abstract

The present study was designed to evaluate the antianxiety and antidepressant potential of Hibiscus sabdariffa Linn. (Malvaceae) calyces, which have been used traditionally as a sedative and for treating other nervous disorders. The study focussed on isolating active principle(s) using bioactivity guided approach. The bioactive ethanol extract of H. sabdariffa calyces was partitioned with ethyl acetate to obtain ethyl acetate soluble and insoluble fractions. The two fractions were evaluated for antianxiety and antidepressant activity. The bioactive ethyl acetate soluble fraction was subjected to successive column chromatography to obtain six fractions (F₁-F₆). Among the six fractions, only F₄ exhibited significant antianxiety and antidepressant activity on Elevated Plus Maze Model and Forced Swim test, respectively. Column chromatography of F₄ yielded three sub-fractions (F_4.1-F_4.3). Bioactive F_4.3 was further subjected to column chromatography which yielded three subfractions – F_4.3.1-F_4.3.3, and a yellow crystalline compound (HS-1) was isolated from F_4.3.2. Based on UV, IR, NMR and MS studies the isolated compound was characterized as gossypetin. Antianxiety and antidepressant activity of HS-1 was evaluated on EPM and FST, respectively. The study showed that gosypetin exhibits significant antianxiety and antidepressant activity at the dose of 5 and 20 mg/kg po, respectively. Present study validates the traditional use of H. sabdariffa calyces in nervous disorders. Gossypetin is the anxiolytic and antidepressant constituents of H. sabdariffa calyces.

Key words:

• Antianxiety
• Antidepressant
• Gossypetin
• Lal Ambari
• Red Sorrel