Abstract

Baptisia tinctoria (Wild indigo; Fabaceae) has long tradition of use in Indian systems of medicine for the treatment of depression. This investigation deals with the evaluation of the antidepressant activity of various extracts and fractions of B. tinctoria roots and estimation of the content of bioactive principle using thin-layer chromatography densitometry. Roots of B. tinctoria were successively extracted to obtain n-hexane, chloroform, methanol and water extracts. The chloroform, methanol and water extracts were screened for antidepressant activity at doses of 200 or 400 mg/kg, p.o., in mice subjected to forced swim test. Methanol extract showed significant activity at a dose of 400 mg/kg. The methanol extract was further fractionated successively to obtain ethyl acetate and 1-butanol fractions. Antidepressant activity of these fractions was assessed using forced swim test at the doses of 90 and 80 mg/kg, p.o., respectively. The ethyl acetate fraction showed significant antidepressant activity at the dose of 90 mg/kg in mice. Further, specific antidepressant activity without psychostimulant effects of bioactive methanol extract and ethyl acetate fraction was confirmed through evaluation of locomotor behaviour in mice using open field test. Phytochemical screening showed the presence of flavonoids as major class of phytoconstituents in the methanol extract. Comparative thin-layer chromatography fingerprint studies confirmed the presence of hesperitin in methanol extract. Hesperitin was used as a chemical marker to standardize B. tinctoria roots using validated thin-layer chromatography densitometric method and the content of hesperitin was found to be 0.0085% w/w.