Enrichment methods for preparing tannic acid compositions
Methods for preparing tannic acid-containing compositions (e.g., pharmaceutical compositions, nutraceutical compositions or medical food compositions), particularly those having enriched tannic acid populations with superior potency, purity and safety profile. Also provide herein are the tannic acid-containing compositions for use in inhibiting D-amino acid oxidase and/or for treating CNS disorder and obesity disorders including diabetes, hyperglycemia, hyperlipidemia or hypercholesterolemia.
1. A method for preparing a tannic acid composition, the method comprising:
(i) providing a composition containing tannic acids;
(ii) extracting the composition with a first solvent to produce a first tannic acid extract; and
(iii) contacting the first tannic acid extract with metal carbonate at 20-60° C. to form a mixture, extracting the mixture with ethyl acetate, methyl acetate, acetone, methyl ethyl ketone, acetonitrile, ethanol, isopropanol, 1,4-dioxane, tetrahydrofuran, or a combination thereof at 20-50° C. to produce an organic solution, and incubating the organic solution with charcoal and metal sulfate at 20-60° C., simultaneously or sequentially, thereby producing a first tannic acid composition.
2. The method of claim 1 , wherein step (ii), is performed at 20-80° C.
3. The method of claim 1 , further comprising contacting the mixture formed in step (iii) with silicon dioxide.
4. The method of claim 1 , wherein step (ii) is performed by incubating multiple batches of the composition with the first solvent sequentially.
5. The method of claim 3 , wherein step (ii) is performed by (a) incubating a first batch of the composition with the first solvent, (b) incubating a second batch of the composition with the mixture formed in (a), and (c) incubating a third batch of the composition with the mixture formed in (b) to produce the first tannic acid extract.
6. The method of claim 3 , further comprising:
(iv) mixing the first tannic acid composition with a second solvent to form a solution;
(v) contacting the solution with dichloromethane, dichloroethane, pentane, hexane, heptane, or a mixture thereof at 20-40° C. to allow for precipitation of tannic acids in solid form; and
(vi) collecting the tannic acids in solid form, thereby producing a second tannic acid composition, wherein <2% of the tannic acids in the second tannic acid composition have 1-4 galloyl moieties.
7. The method of claim 6 , further comprising a step of removing dextrin, gum, and/or resin from the first or second tannic acid composition.
8. The method of claim 7 , wherein the removing step is performed by a process comprising (a) mixing the first or second tannic acid composition with a polar solvent and collecting the organic layer thus formed.
9. The method of claim 8 , wherein the polar solvent is ethyl acetate, methyl acetate, acetone, methyl ethyl ketone, acetonitrile, ethanol, isopropanol, 1,4-dioxane, or tetrahydrofuran.
10. The method of claim 8 , wherein the process for the removing step further comprises (b) contacting the organic layer with an alkyl solvent, a chlorinated solvent, or a mixture thereof at 10-70° C., and (c) collecting the bottom oily layer thus formed.
11. The method of claim 10 , wherein the alkyl solvent is pentane, hexane, or heptane.
12. The method of claim 10 , wherein the chlorinated solvent is dichloromethane or dichloroethane.
13. The method of claim 6 , further comprising (a) mixing the second tannic acid composition with an alkyl solvent, a chlorinated solvent, or a combination thereof, and (b) stirring the mixture thus formed to remove solvent residues at 10-70° C.
14. The method of claim 13 , wherein (i) the alkyl solvent is pentane, hexane, or heptane; and/or (ii) wherein the chlorinated solvent is dichloromethane, or dichloroethane.
15. The method of claim 13 , wherein in step (a), the second tannic acid composition is subject to removal of dextrin, gum, and/or resin.
16. The method of claim 1 , wherein step (ii) is performed at a temperature of 20-60° C.
17. The method of claim 1 , wherein the composition containing tannic acids of step (i) is gallnut powder or gallnut chips obtained from gallnuts of a plant.
18. The method of claim 17 , wherein the plant is selected from the group consisting of Rhus chinensis, Rhus javanica, Rhus semialata, Rhus coriaria, Rhus potaninii, Rhus punjabensis var. sinica (Diels) Rehder & E. H. Wilson, Camellia sinensis , Berry, Bixa orellana, Vitis vinifera, Punica granatum, Quercus infectoria, Quercus cerris, Acacia mearnsii, Pseudotsuga menziesii, Caesalpinia spinosa, Fagus hayata Palib. ex Hayata , and Machilus thunbergii Sieb. & Zucc.
19. The method of claim 17 , wherein the plant is selected from the group consisting of Rhus chinensis, Rhus javanica, Rhus semialata, Rhus coriaria, Rhus potaninii , and Rhus punjabensis var. sinica (Diels) Rehder & E. H. Wilson.
20. The method of claim 17 , wherein the gallnuts have diameters ranging from 1-8 cm.
21. The method of claim 17 , wherein the gallnuts are Chinese belly-shaped gallnuts or horned gallnuts.
22. The method of claim 21 , wherein gallnuts are Chinese horned gallnuts.
23. The method of claim 22 , wherein the Chinese horned gallnuts have diameters ranging from 1-8 cm.
24. The method of claim 23 , wherein the gallnuts have diameters ranging from 2-6 cm.
25. The method of claim 24 , wherein the gallnuts have diameters ranging from 3-5 cm.
26. The method of claim 1 , wherein the metal carbonate in step (iii) is lithium carbonate, sodium carbonate, or potassium carbonate.
27. The method of claim 1 , wherein the metal sulfate in step (iii) is calcium sulfate or magnesium sulfate.
28. The method of claim 1 , wherein the first solvent in step (ii) comprises acetone, acetonitrile, methyl ethyl ketone, ethyl acetate, methyl acetate, ethanol, isopropanol, tetrahydrofuran, 1,4-dioxane, heptane, hexane, water, or a combination thereof.
29. The method of claim 6 , wherein the second solvent is acetone, acetonitrile, ethyl acetate, methyl acetate, methyl ethyl ketone, ethanol, isopropanol, 1,4-dioxane, tetrahydrofuran, or a combination thereof.