1) Weigh 180g of 100-200 mesh column chromatography silica gel, spread it out on a plate, put it into a 1000ml beaker after activation at 110°C for 2h, mix it well with PE, remove air bubbles, and then wet it into a glass chromatography column, and then use PE wash the solid column.
2) Weigh 60 g of 20% Coleus forskohlii extract, when the PE liquid level in the glass column is about 6 cm higher than the silica surface, directly add it to the column by wet method, add it slowly and remove air bubbles, and then add it to the column. After eluting with PE for 30 min, the sample was covered with 2 cm thick chromatographic silica gel, and finally the column was washed with PE.
3) After washing 600ml of the column with PE, directly wash the column with PE-ethyl acetate (10:1); collect in a conical flask, 200ml per bottle, and recover the solvent in a water bath to dryness. The color of the solution washed first is dark and black, and there are many impurity spots in it. When the solvent is recovered to a small volume, it is thicker and darker in color, but it can be dissolved in ethyl acetate, which is discarded here. In this way, the original gradient elution was continued, and the previous strong lipophilic impurities were continuously removed, and the solvent was recovered as much as possible in each bottle, so as to observe the phenomenon.
4) When a large amount of crystals appear in the bottle, collect and combine when opening. The phenomenon at this time is that a large number of crystals are precipitated, and the place washed by the hot solution is bright white, and the rest is brown. The precipitated crystals were carefully dissolved in ethyl acetate, and all the precipitated crystals were combined. When combined to a certain volume, the solvent is recovered in a water bath to a small volume, which is equivalent to 1/3 of the original volume, and the crystals are naturally precipitated due to supersaturation during heat and are naturally precipitated when cooled. When the color is lighter, it is dissolved in ethyl acetate and collected in another device to be combined with the washed crystallization solution. The upper mother liquor was sucked up with a pipette, and the mother liquor and washing liquid continued to be combined with the subsequent crystallizing liquid. Repeated operations in this way, two parts are finally obtained: one part is the crystallization solution that has been repeatedly washed with PE, the color is light brownish yellow, and the other part is the mother liquor, which is very dark and private. After further identification, it was found that there were spots of FSK, but no obvious crystals could be seen when the solution was recovered to 1,000, so the mother liquor was discarded or used for another preparation.
5) Recover the solvent from the crystallization solution until the crystals will precipitate when it is hot, take out the water bath, add 6 times the amount of PE, shake it up a little, and instantly a large number of white crystals will precipitate out, which is very obvious. When it was naturally cooled to room temperature, a large number of white crystals could be seen at the bottom. The crystallization and the mother liquor are separated, and the mother liquor continues to be concentrated until it crystallizes. Finally, two parts of crystals and a dark-colored mother liquor were obtained. After recovering the solvent from the mother liquor to dryness, it was decolorized with PE, and the decolorized solid was dissolved in ethyl acetate and precipitated. After recrystallization twice in this way, a large amount of white crystals was finally obtained, and finally 12.4 g of the product was received. After “testing, the content was 85%.