Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
1999-06-28
2001-04-17
Kight, John (Department: 1625)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
active
06218541
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the extraction of bisbenzylisoquinolines from the root of Stephania Tetrandra S. Moore, and more particularly to a method for obtaining purified bisbenzylisoquinolines from the roots of Stephania Tetrandra S. Moore.
The inventor knows of two prior methods for obtaining purified tetrandrine from the roots of Stephania Tetrandra. The first method involves a refluxing operation in which tetrandrine, fangchinoline, cyclanoline, and various impurities are extracted from the roots of Stephania Tetrandra with ethanol. Tetrandrine and fangchinoline, along with various impurities, are then dissolved by acid solution. Hydrophobic impurities are then removed by filtering. Tetrandrine and fangchinoline are dissociated from the basic solution, to form a milky or cloudy suspension, and then are extracted with chloroform. The chloroform is removed, such as by evaporation, and retrieved, and tetrandrine is separated from fangchinoline by passing the resulting residue through an alumina chromatographic column. This first method is extremely slow and relies on the use of relatively expensive chromatographic separation equipment, and therefore is not conducive to commercial production of tetrandrine.
A second known process involves macerating ground roots of Stephania Tetrandra in the presence of an acidic solution to extract tetrandrine, cyclanoline, fangchinoline, and various soluble impurities from the roots of Stephania Tetrandra. The acidic solution (containing tetrandrine, cyclanoline, fangchinoline and various impurities) is then separated from the depleted roots of Stephania Tetrandra. A base is added to the acid solution to cause precipitation of tetrandrine, fangchinoline and various impurities. The basic solution containing cyclanoline is then separated from the precipitate. The precipitate is then contacted with cool benzene to dissolve tetrandrine. The cool benzene solution (containing tetrandrine and a small portion of the fangchinoline) is separated from a solid residue (which contains a substantial portion of the fangchinoline). Next, the benzene solution (containing tetrandrine) is concentrated to remove benzene, and the removed benzene is retrieved. The benzene extract is then dissolved into acetone. A substantial portion of the acetone is removed from the tetrandrine-rich acetone solution, such as by retrieve. The concentrated acetone solution (which is rich in tetrandrine) is then cooled to cause crystallization of tetrandrine along with a small quantity of impurities. The crystallized material is separated from the acetone, such as by filtration. The crystallized material (including tetrandrine) is redissolved in benzene. The benzene solution is then contacted with activated charcoal to adsorb any remaining impurities and to decolor. Thereafter the benzene solution is separated from the activated charcoal (on which any remaining impurities have been adsorbed) and benzene undissolvable fangchinoline, such as by filtration. Benzene is removed from the resulting filtrate, such as by evaporation, and retrieved. The resulting solid residue is combined with alcohol to recrystallize and decolor the tetrandrine. The pure tetrandrine crystals are separated from the alcohol, such as by filtration. A disadvantage with this second known method is that it involves the use of very large quantities of benzene, a hazardous chemical. Further, this second known method yields only about 3 kilograms of tetrandrine for every metric ton of raw material.
Accordingly, neither of the known processes for obtaining purified tetrandrine from the root of Stephania Tetrandra are commercially attractive.
SUMMARY OF THE INVENTION
In the present invention, higher yields of tetrandrine are economically achieved, while concomitantly reducing the amount of hazardous benzene which is required for obtaining purified tetrandrine from the roots of Stephania Tetrandra, and while eliminating the use of a slow and expensive chromatographic separation.
These goals are achieved in the present invention by obtaining an extract from the roots of Stephania Tetrandra with chloroform, separating the chloroform to obtain a first solid, extracting the first solid with benzene and then removing the benzene to yield a second solid comprising tetrandrine.
In another aspect of the invention, fangchinoline is also extracted from the same raw material by purification and recrystalization of the benzene filtrate left after benzene extraction.
These and other objects, advantages and features of the invention will be more fully understood and appreciated by reference to the written specification and appended drawings.
REFERENCES:
Chong-hou, Xiao, Chinese Medication Chemistry, Trial edition textbook of medical collge and pharmacy college, p. 106, 1987.*
The Merck Index, Eleventh Edition, Centennial Edition, Merck & Co., Inc, Rahway, N.J. U.S.A., (1989); p. 1455.
CBA, International, Inc.
Kight John
Price Heneveld Cooper DeWitt & Litton
Robinson Binta
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