Bioactivity-guided isolation and estimation of hepatoprotective marker compounds from Onosma bracteata; a species of the controversial drug ‘Gojihva’

Gojihva or Gaozaban, an Ayurvedic and Unani medicinal plant, is a commercially important drug with a controversial botanical origin. Onosma bracteata, officially considered Gojihva in India, has very few scientific validations of traditional claims, and few attempts have been made to standardise the plant. The successive extracts were screened for in vitro DPPH assay and hepatoprotective activities (HepG2 cells) to evaluate the traditional claim of vishaghna - antitoxic. The methanol extract has the highest antioxidant capacity of 88.48 ± 0.00% at a concentration of 62.5 µg/mL. The methanol extract at a concentration of 125 µg/mL and above exhibited significant protection against paracetamol and carbon tetrachloride-induced toxicity compared to the control group and other extracts. The caffeic acid and β-sitosterol were isolated from methanol extract, with the latter being reported for the first time. A high-performance thin layer chromatography method was developed for estimating two compounds. The content of caffeic acid and β-sitosterol was found to be 19.06 mg/100 g and 40.42 mg/100 g of the plant material, respectively. Our studies have validated the hepatoprotective property and established quality parameters that are useful for standardisation of O. bracteata and distinguishing it from the other species of Gojihva.