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|Title:||Podophyllotoxin purification process|
|Abstract:||Podophyllotoxin is recovered from podophyllum resin with improved efficiency by adsorbing impurities out of a solution using a solid adsorbent, preferably alumina. This improvement finds application in an overall process for purifying podophyllotoxin from podophyllum resin in which the podophyllotoxin is first crystallized from the podophyllum resin, the crystals so formed are dissolved and subjected to the solid adsorbent treatment, crystals are then recovered and optionally recrystallized and dried to give the desired product.|
|Inventor(s):||Jennings; Rex A. (Holland, MI), Stearns; Jay F. (Santa Rosa, CA)|
|Assignee:||Oclassen Pharmaceuticals, Inc. (San Rafael, CA)|
1. In a process for purifying podophyllotoxin from an impure solution in a solvent comprising an aliphatic halohydrocarbon wherein the podophyllotoxin is recovered as a solid
from the solution, the improvement comprising suspending a high surface area solid inorganic adsorbent with the impure solution to adsorb impurities and removing the solid adsorbent and then recovering the podophyllotoxin as a purified material.
2. The improved process of claim 1 wherein the solid adsorbant is selected from titania, boria and alumina.
3. The improved process of claim 2 wherein the said adsorbant is alumina.
4. The improved process of claim 2 wherein the solvent additionally comprises a polar aprotic cosolvent.
5. The improved process of claim 2 wherein the polar aprotic cosolvent is a ketone.
6. The improved process of claim 2 wherein the polar aprotic cosolvent is acetone.
7. The improved process of claim 2 wherein the polar aprotic cosolvent is an ester.
8. The improved process of claim 2 wherein the polar aprotic cosolvent is an amide.
9. The improved process of claim 2 wherein the solid adsorbant is neutral alumina.
10. The improved process of claim 2 wherein the solid adsorbant is acidic alumina.
11. The improved process of claim 2 wherein the solid adsorbant is mildly basic alumina.
12. A process for isolating podophyllotoxin from podophyllum resin comprising:
a. dissolving podophyllum resin in an organic solvent to yield an impure solution,
b. adding a cosolvent to the impure solution to cause precipitation of a first stage podophyllotoxin product,
c. recovering the precipitated first stage podophyllotoxin product,
d. dissolving the first stage podophyllotoxin product in an organic liquid phase comprising an aliphatic halohydrocarbon to yield a first stage podophyllotoxin product solution,
e. suspending in the first stage podophyllotoxin product solution the solid phase to yield a second stage solution of purified podophyllotoxin,
f. recovering purified podophyllotoxin from the second stage solution as a solid.
13. The process of claim 12 wherein in step e. the high surface area solid is suspended in the first stage podophyllotoxin product solution.
14. The process of claim 12 wherein the high surface area solid is a refractory oxide.
15. The process of claim 14 wherein the refractory oxide is selected from boria, titania and alumina.
16. The process of claim 15 wherein the refractory oxide is alumina.
17. The process of claim 16 wherein the alumina is neutral alumina.
18. The process of claim 16 wherein the alumina is acidic alumina.
19. The process of claim 16 wherein the alumina is mildly basic alumina.
20. The process of claim 16 wherein in step a. the organic solvent comprises a lower alcohol.
21. The process of claim 16 wherein in step b. the cosolvent comprises a nonpolar organic liquid plus water.
22. The process of claim 21 wherein in step b. an acid is present.
23. The process of claim 16 wherein in step d. the organic liquid phase comprises halohydrocarbon liquid plus polar aprotic liquid.
24. The process of claim 23 wherein in step d. the organic liquid phase comprises CH.sub.2 Cl.sub.2 and acetone.
25. The process of claim 16 comprising the additional steps of
g. dissolving the purified solid podophyllotoxin in a solvent to give a third stage solution, and
h. recovering pure podophyllotoxin as a recrystallized solid from the third stage solution.
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