Hylan preparation and method of recovery thereof from animal tissues
First Claim
1. A method of obtaining a chemically modified hyaluronic acid preparation comprising:
- (a) treating animal tissue containing hyaluronic acid with an aqueous treating mixture including an aldehyde to effect chemical modification of the hyaluronic acid contained in the tissue, in situ,(b) removing excess treating mixture from the reaction mixture,(c) extracting the chemically modified hyaluronic acid from the treated animal tissue with water at a temperature below about 16°
C. and an alkaline pH of from 8 to 14 and beyond for about 6 hours to several days, the weight ratio of water to treated tissue being about 2-5;
1 based on the weight of the treated tissue,(d) separating the extract containing the chemically modified hyaluronic acid from the treated animal tissue, and(e) recovering the chemically modified hyaluronic acid from the extract.
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Abstract
Disclosed is hylan, a chemically modified hyaluronan preparation characterized by the presence of small amounts (0.0002-0.05% by weight) of aldehyde cross-linking groups covalently bonded to the hyaluronan molecular chains. Also disclosed is an improved method of obtaining hylan comprising treating hyaluronan in situ in animal tissues containing same with a treatment mixture including an aldehyde which is reactive towards hyaluronic acid and the proteins contained in the animal tissue. Treatment is effected at temperatures below about 16° C. at very high pH, e.g., 8-14 whereby the overall yield is increased while maintaining the high molecular weight of the hylan.
78 Citations
45 Claims
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1. A method of obtaining a chemically modified hyaluronic acid preparation comprising:
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(a) treating animal tissue containing hyaluronic acid with an aqueous treating mixture including an aldehyde to effect chemical modification of the hyaluronic acid contained in the tissue, in situ, (b) removing excess treating mixture from the reaction mixture, (c) extracting the chemically modified hyaluronic acid from the treated animal tissue with water at a temperature below about 16°
C. and an alkaline pH of from 8 to 14 and beyond for about 6 hours to several days, the weight ratio of water to treated tissue being about 2-5;
1 based on the weight of the treated tissue,(d) separating the extract containing the chemically modified hyaluronic acid from the treated animal tissue, and (e) recovering the chemically modified hyaluronic acid from the extract. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43)
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- 44. A chemically modified hyaluronic acid preparation characterized by the presence of about 0.0002 to 0.05% by weight of aldehyde cross-linking groups covalently bonded to the hyaluronic acid polymer chains.
Specification