| 主权项 |
1. A method for preparing a refined extract of Centella asiatica comprising more than 50% wt. of a mixture of madecassoside and terminoloside in relation to the total weight of the extract, said method comprising the following steps:
a. maceration under stirring of the aerial parts of leaves of the Centella asiatica plant in water or in a solvent mixture, comprising at least water and optionally an alcoholic solvent, at a temperature of 20 to 90° C. and for between 20 and 180 minutes, wherein a ratio of Centella asiatica to the solvent mixture is between 1:2 and 1:20, followed by filtration of the maceration mixture, whereby an aqueous solution is obtained;
α. passage of the aqueous solution obtained over an adsorbent resin to adsorb triterpene heterosides, wherein said adsorbent resin is styrene-divinylbenzene or phenol formaldehyde resin;β. elution of said triterpene heterosides from said adsorbent resin with an eluent comprising at least 30% wt. of an alcoholic solvent and optionally water, whereby an eluate is obtained, followed by:treatment of the eluate obtained with activated carbon; b. passage of the treated eluate over a strong anionic styrene-chloride type discoloring resin followed by treatment by means of successive passage(s) over a strong cationic ion exchange resin comprising sulfonate type functional groups, and over a strong anionic ion resin comprising quaternary ammonium type functional groups, or passage of the eluate over said mixed resins, whereby a discolored aqueous phase is obtained; c. vacuum-concentration of the discolored aqueous phase using tangential filtration membrane techniques on an organic or mineral membrane, using media having a cut-off threshold between 200 kDa and 100 kDa, whereby an extract is obtained, followed by recrystallization of the extract obtained by: d. solubilization of the extract obtained in a solvent mixture comprising 70 vol. % water and 30 vol. % methanol, carried to a temperature between 55° C. and 65° C., whereby a solution is obtained; e. reduction of the temperature over a period from 100 to 250 hours to a cooled mixture temperature between −10° C. and 10° C., whereby a cooled mixture is obtained; f. filtration of the cooled mixture, whereby a filtrate is obtained; and g. concentration of the filtrate by distillation, whereby a refined extract comprising less than 15% wt. of asiaticoside in relation to the total weight of the extract is obtained. |
