This invention discloses a novel method for extracting
swainsonine from
locoweed. The method comprises: (1) extracting
locoweed powder with
ethanol at a ratio of 1:(6-10) for 3 times (4 h each time), filtering, recovering
ethanol, dissolving the residue with 3-5 times of
ethanol, recovering ethanol to obtain an extractum, adding 2%
acetic acid to adjust the pH value to 4.5-6, adding 50-100 times of
chloroform, and recovering the
chloroform layer; (2) extracting the acidic
water layer with 50 times of
chloroform for twice, recovering chloroform,
drying the acidic water at 50-60 deg.C to obtain crude alkaloids, completely dissolving in 1 M
ammonium solution, adding 10% NaOH solution (1 mL / 45-75 g) and
methanol (5 mL / 45-75 g) into alkaloids solution, extracting with
dichloromethane repeatedly until the solution color is light, adding
ammonium solution to completely dissolve the residue, extracting with
dichloromethane, and recovering
dichloromethane to obtain crude
swainsonine; (3) dissolving with
methanol, evaporating
methanol, and sublimating to obtain white needle-like crystals. The method has such advantages as easy operation, and high extraction rate.