Bioactivity Guided Fractionation of Ethanol Extract of Caesalpinia digyna Rottler Roots

Background: Authors have reported earlier that ethanol extract of Caesalpinia digyna Rottler roots exhibits significant antianxiety activity at 400 mg/kg, po, in mice using elevated plus-maze (EPM). Objective: Aim of the study was to isolate antianxiety principle(s) from ethanol extract of C. digyna roots following bioactivity guided fractionation approach. Materials and Methods: Bioactive ethanol extract was partitioned with ethyl acetate to get ethyl acetate soluble (EASF) and ethyl acetate insoluble (EAIF) fractions. A compound (CD₁) precipitated from EASF. The two fractions and CD₁ were evaluated for antianxiety activity in mice. Column chromatography of EASF yielded 5 fractions (F₁-F₅), all of which were evaluated for antianxiety activity using EPM. Results: Present study revealed that EASF (80 mg/kg) and CD₁ (40 mg/kg) exhibited significant antianxiety activity, while EAIF does not. Among the five fractions, only F4 (40 mg/kg, po), exhibited significant antianxiety activity, which was statistically comparable to that of diazepam (2 mg/kg). Conclusion: Present investigation reveals that EASF obtained by partitioning of ethanol extract of C. digyna roots with ethyl acetate, and a compound CD₁, isolated from EASF, exhibit significant antianxiety activity. Among 5 fractions (F₁-F₅) obtained from column chromatography of EASF, only F4 exhibited significant antianxiety activity. F4 is being processed further to isolate the anxiolytic constituent(s), and CD₁ is being characterized.