Glucan gels
The present invention relates to a glucan having a weight average molar mass of 15,000 to 50,000 g/mol on a single chain basis and a weight average molar mass in aqueous solution on an aggregate basis of 4 to 20×10 5 g/mol and existing in gel form in aqueous solution at a concentration ≧1% at 25° C. and neutral pH and having a melting temperature (gel to sol) of 35 to 60° C. when the glucan is dissolved in water at a concentration of 2%, methods for the production thereof, medical uses thereof, physical supports having the glucan applied thereto or impregnated thereon and in vitro methods of proliferation of skin cells which comprise contacting a population of skin cells with the glucan.
1. A gel glucan product comprising a soluble yeast glucan in aqueous solution at a concentration of 1 to 6%, the glucan having a weight average molar mass of 15,000 to 50,000 g/mol on a single chain basis and a weight average molar mass in aqueous solution on an aggregate basis of 4 to 20×10 5 g/mol, the gel glucan product having a gel to sol melting temperature of 35 to 60° C.
2. The gel glucan product of claim 1 , wherein the glucan has a weight average molar mass of 20,000 to 40,000 g/mol on a single chain basis.
3. The gel glucan product of claim 1 , wherein the glucan has a melting temperature (gel to sol) of about 40° C.
4. The gel glucan product of claim 1 , wherein the glucan is in aqueous solution at a concentration of about 2%.
5. The gel glucan product of claim 1 , wherein the glucan is derived from Saccharomyces cerevisiae.
6. The gel glucan product of claim 1 , wherein the glucan is a beta glucan comprising a backbone of β-(1,3)-linked glucosyl residues and side chains comprising 2 or more β-(1,3)-linked glucosyl residues, the sidechains being attached to the backbone via a β-(1,6)-linkage.
7. The gel glucan product of claim 1 , wherein the glucan is essentially free of repetitive β-(1,6)-linked glucosyl residues.
8. A method of producing a gel glucan product, said method comprising the following steps:
a) treating an aqueous solution of soluble glucan molecules with an agent which dissociates the glucan's hydrogen bonds; and
b) contacting the product of step a) with an agent which enables reformation of hydrogen bonds within the glucan;
wherein in step a) the glucan is derived from yeast and is in aqueous solution at a concentration of about 1% to wbout 6%, the glucan having a weight average molar mass of 15,000 to 50,000 g/mol on a single chain basis and a weight average molar mass in aqueous solution on an aggregate basis of 4 to 20×10 5 g/mol.
9. The method of claim 8 , wherein the agent which dissociates the hydrogen bonds is an alkali salt, sodium hydride, sodium amide, urea or formamide.
10. The method of claim 9 , wherein the agent which dissociates the hydrogen bonds is sodium hydroxide.
11. The method of claim 8 , wherein the agent which dissociates the hydrogen bonds is used at a final concentration of above 50 mM.
12. The method of claim 11 , wherein the agent which dissociates the hydrogen bonds is used at a final concentration of about 150 mM.
13. The method of claim 8 , wherein the agent which enables reformation of hydrogen bonds is a strong acid.
14. The method of claim 13 , wherein the acid is hydrochloric acid, formic acid, sulphuric acid, phosphoric acid, acetic acid or citric acid.
15. The method of claim 8 wherein step b) results in gel formation in less than 10, preferably less than 4 minutes.
16. The method of claim 8 , wherein the agents of step a) and b) are added in equimolar amounts.
17. The method of claim 8 which is preceded by a formolysis step wherein a particulate glucan starting material is suspended in formic acid in order to remove β-(1,6) linked glucosyl side chains and to solubilise the particulate glucan.
18. A gel glucan product obtainable by the method of claim 8 .
19. A pharmaceutical composition comprising the gel glucan product of claim 1 and one or more pharmaceutically acceptable diluents or carriers.
20. A pharmaceutical composition comprising the gel glucan product of claim 18 and one or more pharmaceutically acceptable diluents or carriers.