1. Crush Centella asiatica, extract with 60-70v% ethanol solution in a stream, filter the extract, recover the solvent from the filtrate, add 40-50C water to dissolve, filter, and dissolve the filter residue in 50-60v% ethanol solution to obtain crude extract.
2. Put the crude extract on XAD-9 manhole resin column, elute with acid solution with a pH value of 2-4, and combine flow solution and acid wash solution.
3. Adjust the pH value of the combined solution to neutral, filter it, and refill the filtrate with EXAD-3 macroporous resin column, elute with ethanol with a volume concentration of 30-40%, track and detect by thin-layer chromatography, and collect components containing asiatic acid ethanol eluate; then volume concentration, 55-65% ethanol elution, thin layer, chromatography tracking detection, collection of ethanol eluate containing madecassic acid, the madecassic acid eluate Recover ethanol and dry to obtain madecassic acid.
In step 1, ethanol with a volume concentration of 60-70% can fully dissolve the diterpenoids in Centella asiatica, including triterpene saponins and triterpene acids. Because the molecules of centella asiatica soap are often combined with many sugar molecules, and the number of hydroxyl groups is large, it can show a certain degree of hydrophilicity, but the hydrophilicity is not strong enough, and it is slightly soluble in water, while diterpene acids are polar. Small and insoluble in water. Therefore, the use of warm water at 40-50°C can help the total saponins of Centella asiatica to dissolve, and the acid substances of centella asiatica are insoluble in hot water. Filter the filtrate, take the filter residue and dissolve it in ethanol to achieve the daily goal of removing total saponins of Centella asiatica. .
XAD-9 resin mainly adsorbs fat-soluble components and macromolecular substances with strong polarity. These substances have stronger adsorption to the resin, and the macroporous resin preferentially adsorbs these substances and quickly reaches saturation. XAD-9 is a polar macroporous resin, which has a large difference in polarity from triterpene acids, so it cannot effectively adsorb triterpene acids. It plays the role of physically intercepting triterpenic acid compounds, so the triterpene acid compounds will flow out with the effluent. The elution with acid solution with a pH value of 2-4 can further elute a small amount of triterpene acid compounds adsorbed in the resin to avoid the adsorption loss of triterpene acid compounds.
In step 2, the column speed of the crude extract is 3-5BV/h. The elution rate of acid solution is 1-2BV/h.
In step 3, the XAD-3 model macroporous resin is a non-polar resin with an average pore diameter of 0.44um and a specific surface area of 256m2/g. The resin has very good adsorption properties for triterpenic acid compounds, and the column loading speed of the filtrate is 0.5-1BV/h, which can completely adsorb diterpenic acid compounds. Due to the difference in polarity between Asiatic acid and Madecassic Acid, Asiatic acid can be preferentially eluted by ethanol with a volume concentration of 30-40%. Then elute with ethanol with a volume concentration of 55-65%, and the remaining Madecassic Acid can be eluted.
Compared with the prior art, this method performs adsorption and desorption on target components, and the yield of extracted Madecassic Acid is as high as 90%, and the purity is as high as 95.0%.
