In Berberis species (B. aristata, B. glauca, B. vulgaris, B. aquifolium etc.) berberine alkaloids are principally located in the cortical tissues and the bark of old roots has the highest concentration. Upper parts of the shoot system have a low concentration of alkaloids and in young leaves they are not detectable. Berberine content varies depending on the species and different plant parts. While Berberis species has 0.12% to 2.8%, Hydrastis species has 1% to 5% of berberine. Plants which contain berberine as the principal alkaloid may be processed for its isolation.

1. Weigh 50 g of the powdered plant material and pack it in a Soxhlet extractor. Subject it to hot continuous percolation using 250 ml ethanol for 4 h.
2. Concentrate the ethanol extract in a rotary vacuum evaporator to a pasty residue.
3. Dissolve the residue in minimum quantity of hot water (100 ml). Insoluble resins which separate out are removed by filtration of the hot solution. Reduce the volume of the filtrate by evaporation to about 20 ml.
4. Treat the filtrate with concentrated hydrochloric acid to a pH of 1 to 2. Berberine hydrochloride that crystallizes out is separated by filtration through a Buchner funnel.
5. For purification of the alkaloid it is recrystallized from ethanol using ether for precipitation.
6. Carefully separate the crystals and dissolve in hot water (5–10 ml). Make the solution alkaline by adding a few drops of 10% sodium hydroxide.
7. Add 2 ml acetone and dilute the solution with an equal volume of water. Set aside overnight in a refrigerator for complete precipitation of berberine-acetone complex.
8. Filter carefully and wash the precipitate with ice-cold water and dissolve the air-dried berberine-acetone in ethanol: chloroform (10:1).
9. Heat the solution to boiling and allow it to cool. Separate the crystals of pure berberine by centrifugation and dry in a desiccator to constant weight.