Patent GB-650783-A (GB)
Title: Improvements in and relating to the degradation of dextran
IPC: C08B37/02
Filed: 1947-07-28
Abstract: The required fraction of partly depolymerized dextran is obtained from the liquid resulting from the action of a dilute mineral acid upon a dextran-containing solution obtained by the growth of such organisms as Leuconostoc meserentoides or L. dextranicum in saccharose solution, after adjustment of the pH of the liquid to 7-8, e.g. with sodium hydroxide or carbonate, by adding sufficient acetone to precipitate the dextran of undesirably large molecular size, removing this precipitate, again adding acetone to the remaining liquid to precipitate dextran of the desired molecular size, separating this fraction, and discarding the residual liquid.  By adding calcium chloride to the depolymerized dextran-containing liquid and heating to 50-60 DEG  C. calcium phosphate and sulphate are precipitated, and this precipitate entrains a large proportion of the nitrogen-containing compounds which may be present; after filtering or centrifuging off this precipitate, acetone is added to the liquid to precipitate dextran which has, in a 6 g./100 ml. solution in water, a viscosity, measured in a viscometer having a water-flow time of 10 sec. of not less than 3.8 relative to water; the desired dextran is contained within the fraction having a relative viscosity, similarly measured, of not less than 3.2, which fraction is obtained by adding more acetone; further fractionation by acetone of this fraction is undertaken to obtain a product having the relative viscosity 3.3-3.4.ALSO:A fraction of partly depolymerized dextran suitable for therapeutic use is obtained from the liquid resulting from the action of a dilute mineral acid upon a dextran containing solution obtained by the growth of such organisms as Leuconostoc-meserentoides or L. dextranicum in saccharose solution, after adjustment of the pH of the liquid to 7-8, by adding sufficient acetone to precipitate the dextran of considerably large molecular size, removing this precipitate, again addng acetone to the remaining liquid to precipitate dextran of the desired molecular size, separating this fraction, and discarding the residue liquid.  By adding calcium chloride to the depolymerized dextran-containing liquid and heating to 50-60 DEG  C. calcium phosphate and sulphate are precipitated, and this precipitate entrains a large proportion of the nitrogen-containing compounds which may be present after filtering or centrifuging off this precipitate, acetone is added to the liquid to precipitate dextran which has, in a 6g./100 ml. solution in water, a viscosity, measured in a viscometer having a waterflow time of 10 sec., of not less than 3.8 relative to water; the desired dextran is contained within the fraction having a relative viscosity, similarly measured, of not less than 3.2, which fraction is obtained by adding more acetone; futher fractionation by acetone of this fraction is undertaken to obtain a product having the relative viscosity 3.3-3.4; acetone is removed by evaporation under vacuum.  To a solution to be used as a blood plasma substitute is added 0.89g. of sodium chloride per 100 ml., and the pH is adjusted to 7.0 by adding hydrochloric acid or sodium hydroxide.