1. Extraction of total alkaloids and separation of lipophilic and hydrophilic alkaloids
Tetrandrine is an alkaloid, and the plant raw material is Tetrandrine (root). The principle of extraction and separation is the higher content or the main component and the difference in dissolution, which is called acid water percolation. The separation method is as follows:
2. Separation of tetrandrine and B by low-pressure column chromatography
Low-pressure column chromatography is used under low pressure (0.5-3kg/cm2, generally 0.3-1.2kg/cm2) for thin-layer chromatography with a particle diameter between classical column chromatography (100-200μm) and HPLC (~37μm). Silica gel (or alumina) H or G (50-75μm) is used as a column chromatography column as a filler. Its basic principle is the same as that of HPLC, and its separation effect is also between that of classical columns and HPLC. It is packed by vacuum dry method. The layer is compact and uniform, and the chromatographic bands are uniformly distributed. At the same time, the optimal separation solvent system of thin-layer chromatography can be directly used in low-pressure column chromatography. It is a kind of separation effect, simple equipment, convenient operation, fast Methods. Suitable for constant preparative separation of natural products.
(1) Column packing
Vacuum dry installation method, column specifications: column length 30cm, inner diameter 2cm, a total of about 30g of silica gel (about 22cm in height). Add it to 1.5g of silica gel with a dropper, mix well, evaporate to dryness on a water bath, grind it finely, carefully add it to the top of the column through a long-necked funnel, and tap it vertically until the surface of the sample is flat and does not stir , Cover it with blank silica gel about 1-2cm high, and then cover it with a circular filter paper, and press it tightly.
First check whether the valves and pipelines from the air compressor to the chromatography column are normal, close each valve tightly, and start the air compressor to the rated pressure (5.8kg/cm2) for use. Use a dropper to carefully add a small amount of eluent (cyclohexane-ethyl benzylate-diethylamine/6:2:0.8) along the column wall of the chromatography column. When the liquid level reaches a certain height, add the rest of the eluent again. (About 250ml in total), quickly install a glass plug connector on the top of the column, press it tightly with an iron clip (to prevent the connector from being flushed when pressurized), carefully open the air compressor valve, and then open the needle valve and air filter to reduce the pressure. Pressure device, (note: the pressure is too high. The glass column will explode, generally 2kg is safe, and a protective mask can be worn if necessary) to adjust the required pressure, 0.6～1.2kg/cm2, it will flow out after about 40 minutes, control the flow rate 1ml/cm2 Divide into one tube every 10 minutes, collect 12-15 copies, and the whole process of elution takes about 3 hours.
Each fraction was transferred into a small glass evaporator, concentrated on a water bath, and checked by TLC respectively. Adsorbent: silica gel G, developer: cyclohexane-ethyl acetate-diethylamine/6:3:1, modified iodine Bismuth Potassium Reagent was sprayed for color development, with Tetrandrine and B as the standard control, the same components were combined to obtain crude A and B respectively, recrystallized with acetone, and determined.