Synthetic polysaccharides, process for their preparation and pharmaceutical compositions containing them

1. A synthetic polysaccharide containing from 8 to 24 monosaccharide units comprising a sequence of disaccharides formed from a uronic acid and from a hexose, said polysaccharide having its hydroxyl groups etherified with a (C 1 -C 6 )alkyl group or esterified in the form of a sulpho group, each disaccharide being at least monoetherified, having the formula:

in which

the wavy line indicates either a bond below or above the plane of the pyranose ring;

R 1 , R 6 , R 11 and R 16 are a (C 1 -C 6 )alkyl;

R 2 , R 3 , R 4 , R 5 , R 7 , R 8 , R 9 , R 10 , R 12 , R 13 , R 14 , R 15 and R 17 are a (C 1 -C 6 )alkyl or an SO 3 − group;

m, n and p are such that the sum m+n+p is greater than or equal to 4 and less than or equal to 12, one or two of the three being able to be zero;

and the salts thereof and the acids corresponding thereto.

2. A polysaccharide according to claim 1 formed from an anion and from a cation, wherein the anion has the formula (I.1):

in which m is 4 to 10; R 1 and R 16 are a (C 1 -C 6 )alkyl and R 15 and R 17 are a (C 1 -C 6 )alkyl or an SO 3 − group, each uronic acid being either an iduronic or glucuronic acid; and the cation is a pharmaceutically acceptable monovalent cation; and the salts thereof and the acids corresponding thereto.

3. A polysaccharide of claim 1 wherein the alkyls are methyls and the salts thereof and the acids corresponding thereto.

4. A polysaccharide of claim 1 wherein n and p are equal to zero and the salts thereof and the acids corresponding thereto.

5. A polysaccharide of claim 1 wherein n and p are equal to zero and m is 4 to 10 and the salts thereof and the acids corresponding thereto.

6. A polysaccharide of claim 1 wherein n and p are equal to zero, m is 4 to 10; at least one of the substituents R 12 , R 13 , R 14 and R 15 is a sulphate group; R 1 and R 16 are a (C 1 -C 6 )alkyl and R 17 is a (C 1 -C 6 )alkyl or an SO 3 − group and the salts thereof and the acids corresponding thereto.

7. A polysaccharide of claim 1 wherein n and p are equal to zero, m is 4 to 10; at least two of the substituents R 12 , R 13 , R 14 and R 15 are a sulphate group; R 1 and R 16 are a (C 1 -C 6 )alkyl and R 17 is a (C 1 -C 6 )alkyl or an SO 3 − group and the salts thereof and the acids corresponding thereto.

8. A polysaccharide of claim 1 wherein n and p are equal to zero, m is 4 to 10; at least three of the substituents R 12 , R 13 , R 14 and R 15 are a sulphate group; R 1 and R 16 are a (C 1 -C 6 )alkyl and R 17 is a (C 1 -C 6 )alkyl or an SO 3 − group and the salts thereof and the acids corresponding thereto.

9. A polysaccharide according to claim 2 in which the cation is selected from sodium and potassium.

10. A polysaccharide according to claim 1 formed from an anion and from a cation, wherein the anion has the formula (I.2):

in which m is 4 to 10; R 1 and R 16 are a (C 1 -C 6 )alkyl and R 15 and R 17 are a (C 1 -C 6 )alkyl or an SO 3 − group, each uronic acid being either an iduronic or glucuronic acid; and the cation is a pharmaceutically acceptable monovalent cation; and the salts thereof and the acids corresponding thereto.

11. A polysaccharide according to claim 1 formed from an anion and from a cation, wherein the anion has the formula (I.3):

in which m is 2 or 3; R 1 and R 16 are a (C 1 -C 6 )alkyl and R 12 , R 13 , R 14 , R 15 and R 17 are a (C 1 -C 6 )alkyl or an SO 3 − group, each uronic acid being either an iduronic or glucuronic acid; and the cation is a pharmaceutically acceptable monovalent cation; as well as the salts thereof and the acids corresponding thereto.

12. A polysaccharide according to claim 11 in which R 1 is a methyl, R 13 in position 3 of the glucose is a methyl, R 12 in position 2 and R 14 in position 6 of the glucose are an SO 3 − and R 16 in position 3 of the iduronic or glucuronic unit is a methyl, and m is equal to 2 or 3.

13. A polysaccharide chosen from the group consisting of:

methyl (1-4)-O-(2,3-di-O-methyl-4-O-sulpho-α-L-idopyranosyluronic acid)-[(1-4)-O-(2,3,6-tri-O-sulpho-α-D-glucopyranosyl)-(1-4)-O-(2,3-di-O-methyl-α-L-idopyranosyluronic acid)] 9 -2,3,6-tri-O-sulpho-α-D-glucopyranoside, sodium salt,

methyl (1-4)-O-(2,3-di-O-methyl-4-O-sulpho-α-L-idopyranosyluronic acid)-[(1-4)-O-(2,3,6-tri-O-sulpho-α-D-glucopyranosyl)-(1-4)-O-(2,3-di-O-methyl-α-L-idopyranosyluronic acid)] 4 -2,3,6-tri-O-sulpho-α-D-glucopyranoside, sodium salt,

methyl (1-4)-O-(2,3-di-O-methyl-4-O-sulpho-α-L-idopyranosyluronic acid)-[(1-4)-O-(2,3,6-tri-O-sulpho-α-D-glucopyranosyl)-(1-4)-O-(2,3-di-O-methyl-α-L-idopyranosyluronic acid)] 5 -2,3,6-tri-O-sulpho-α-D-glucopyranoside, sodium salt,

methyl (1-4)-O-(2,3-di-O-methyl-4-O-sulpho-α-L-idopyranosyluronic acid)-[(1-4)-O-(2,3,6-tri-O-sulpho-α-D-glucopyranosyl)-(1-4)-O-(2,3-di-O-methyl-α-L-idopyranosyluronic acid)] 6 -2,3,6-tri-O-sulpho-α-D-glucopyranoside, sodium salt,

methyl (1-4)-O-(2,3-di-O-methyl-4-O-sulpho-α-L-idopyranosyluronic acid)-[(1-4)-O-(2,3,6-tri-O-sulpho-α-D-glucopyranosyl)-(1-4)-O-(2,3-di-O-methyl-α-L-idopyranosyluronic acid)] 7 -2,3,6-tri-O-sulpho-α-D-glucopyranoside, sodium salt,

methyl (1-4)-O-(2,3-di-O-methyl-4-O-sulpho-α-L-idopyranosyluronic acid)-[(1-4)-O-(2,3,6-tri-O-sulpho-α-D-glucopyranosyl)-(1-4)-O-(2,3-di-O-methyl-α-L-idopyranosyluronic acid)] 8 -2,3,6-tri-O-sulpho-α-D-glucopyranoside, sodium salt,

methyl (1-4)-O-(2,3-di-O-methyl-4-O-sulpho-β-D-glucopyranosyluronic acid)-[(1-4)-O-(2,3,6-tri-O-sulpho-α-D-glucopyranosyl)-(1-4)-O-(2,3-di-O-methyl-β-D-glucopyranosyluronic acid)] 4 -2,3,6-tri-O-sulpho-α-D-glucopyranoside, sodium salt,

methyl (1-4)-O-(2,3-di-O-methyl-4-O-sulpho-β-D-glucopyranosyluronic acid)-[(1-4)-O-(2,3,6-tri-O-sulpho-α-D-glucopyranosyl)-(1-4)-O-(2,3-di-O-methyl-β-D-glucopyranosyluronic acid)] 3 -2,3,6-tri-O-sulpho-α-D-glucopyranoside, sodium salt,

methyl (1-4)-O-(3-O-methyl-2,4-di-O-sulpho-α-L-idopyranosyluronic acid)-[(1-4)-O-(3-O-methyl-2,6-di-O-sulpho-α-D-glucopyranosyl)-(1-4)-O-(3-O-methyl-2-O-sulpho-α-L-idopyranosyluronic acid)] 4 -3-O-methyl-2,6-di-O-sulpho-α-D-glucopyranoside, sodium salt,

methyl (1-4)-O-(3-O-methyl-2,4-di-O-sulpho-α-L-idopyranosyluronic acid)-[(1-4)-O-(3-O-methyl-2,6-di-O-sulpho-α-D-glucopyranosyl)-(1-4)-O-(3-O-methyl-2-O-sulpho-α-L-idopyranosyluronic acid)] 3 -3-O-methyl-2,6-di-O-sulpho-α-D-glucopyranoside, sodium salt,

methyl O-(3-O-methyl-2,4-di-O-sulpho-α-L-idopyranosyluronic acid)-[(1-4)-O-(3-O-methyl-2,6-di-O-sulpho-α-D-glucopyranosyl)-(1-4)-O-(3-O-methyl-2-O-sulpho-α-L-idopyranosyluronic acid)(1-4)-] 5 -3-O-methyl-2,6-di-O-sulpho-α-D-glucopyranoside, sodium salt,

methyl (1-4)-O-(3-O-methyl-2,4-di-O-sulpho-β-D-glucopyranosyluronic acid)-[(1-4)-O-(3-O-methyl-2,6-di-O-sulpho-α-D-glucopyranosyl)-(1-4)-O-(3-O-methyl-2-O-sulpho-β-D-glucopyranosyluronic acid)] 4 -3-O-methyl-2,6-di-O-sulpho-α-D-glucopyranoside, sodium salt,

methyl (1-4)-O-(3-O-methyl-2,4-di-O-sulpho-α-L-idopyranosyluronic acid)-[(1-4)-O-(3-O-methyl-2,6-di-O-sulpho-α-D-glucopyranosyl)-(1-4)-O-(3-O-methyl-2-O-sulpho-α-L-idopyranosyluronic acid)] 2 -O-(2,3,6-tri-O-sulpho-α-D-glucopyranosyl)-(1-4)-O-(3-(1-4)-O-methyl-2-O-sulpho-α-L-idopyranosyluronic acid)-3-O-methyl-2,6-di-O-sulpho-α-D-glucopyranoside, sodium salt, and

methyl (1-4)-O-(3-O-methyl-2,4-di-O-sulpho-α-L-idopyranosyluronic acid)-[(1-4)-O-(3-O-methyl-2,6-di-O-sulpho-α-D-glucopyranosyl)-(1-4)-O-(3-O-methyl-2-O-sulpho-α-L-idopyranosyluronic acid)] 3 -(1-4)-O-(2,3,6-tri-O-sulpho-α-D-glucopyranosyl)-(1-4)-O-(3-O-methyl-2-O-sulpho-α-L-idopyranosyluronic acid)-3-O-methyl-2,6-di-O-sulpho-α-D-glucopyranoside, sodium salt.

14. A process for the preparation of compounds of formula (I):

and the salts

in which

the wavy line indicates either a bond below or above the plane of the pyranose ring;

R 1 , R 6 , R 11 and R 16 are a (C 1 -C 6 )alkyl;

R 2 , R 3 , R 4 , R 5 , R 7 , R 8 , R 9 , R 10 , R 12 , R 13 , R 14 , R 15 and R 17 are a (C 1 -C 6 )alkyl or an SO 3 − group;

m, n and p are such that the sum m+n+p is greater than or equal to 4 and less than or equal to 12, one or two of the three being able to be zero;

said process comprising the steps of:

(a) coupling a glycosidic link donor monosaccharide to a glycosidic link acceptor monosaccharide to obtain an intermediate saccharide synthon of completely protected disaccharide type of formula (A):

in which the identical or different T 1 , T 2 , T 3 , T 4 , T 5 , T 6 , T 7 and Z substituents are selected from the protective groups used in sugar chemistry as permanent, semi-permanent or temporary protective groups,

(b) chemically modifying the disaccharide of formula (A) above to obtain an intermediate saccharide synthon of glycosidic link donor disaccharide type of formula (B):

in which T 2 to T 7 and Z are as defined above for (A) and X is an activating group of the anomeric carbon, then

(c) chemically modifying the disaccharide of formula (A) above to obtain an intermediate saccharide synthon of glycoside link acceptor disaccharide type of formula (C):

in which T 1 to T 7 are such as defined above for (A), by selectively eliminating the protective group Z, then

(d) coupling a glycosidic link donor disaccharide of formula (B) obtained above and a glycosidic link acceptor disaccharide of formula (C) obtained above to obtain a completely protected tetrasaccharide of formula (D):

in which T 1 to T 7 and Z are such as defined above for (A) and T 8 , T 9 , T 10 , T 11 , T 12 and T 13 are such as defined for T 2 to T 7 then,

(e) chemically modifying the intermediate saccharide synthon of tetrasaccharide type of formula (D) to obtain an intermediate saccharide synthon of glycosidic link donor tetrasaccharide type of formula (E):

in which X has the same definition as for (B) and T 2 to T 13 are such as defined for (D) then,

(f) selectively deprotecting the tetrasaccharide of formula (D) to obtain a glycosidic link acceptor tetrasaccharide of formula (F):

in which T 1 to T 13 are such as defined above for (D) then,

(g) coupling the glycosidic link acceptor tetrasaccharide of formula (F) and a glycosidic link donor disaccharide of formula (B) such as those obtained above to form an intermediate synthon of completely protected hexasaccharide type of formula (G):

in which T 1 to T 13 are such as defined above for (D) and T 14 to T 19 are such as defined for T 2 to T 7 for (B);

or coupling the glycosidic link acceptor tetrasaccharide of formula (F) and a glycosidic link donor tetrasaccharide of formula (E) to obtain a completely protected octasaccharide of formula (H):

in which T 1 to T 19 and Z are such as defined previously and T 20 to T 25 are such as defined for T 2 to T 7 for (B) then,

(h) chemically modifying the hexasaccharide of formula (G) or the octasaccharide of formula (H) obtained above to obtain an intermediate synthon of glycosidic link acceptor hexasaccharide type of formula (G) in which Z is hydrogen or else a glycosidic link acceptor octasaccharide of formula (H) in which Z is hydrogen,

(i) repeating the above deprotection and coupling steps until the completely protected oligosaccharide having the desired structure is obtained, the glycosyl donor and glycosyl acceptor intermediate saccharide synthons being chosen as a function of the final structure to thus obtain the protected precursor of the desired final polysaccharide of formula (I), in which the nature of the protective substituents determines the position of the alkyl and sulphate groups on the final product (I), and

(j) deprotecting the alcohol functions which must be sulphated by eliminating the substituents T 1 to T 25 which protected the functions in the course of the steps of elaboration of the skeleton, then, finally

(k) carrying out the sulphation to obtain the compounds (I), or one of their salts.

15. A pharmaceutical composition containing a polysaccharide or salt thereof according to claim 1 in-combination with an inert, non-toxic, pharmaceutically acceptable excipient.

16. A pharmaceutical composition according to claim 15 , in the form of a dosage unit.

17. A pharmaceutical composition according to claim 16 in which each dosage unit contains from 0.1 to 100 mg of the polysaccharide.

18. A pharmaceutical composition according to claim 17 in which each dosage unit contains from 0.5 to 50 mg of the polysaccharide.

19. The polysaccharide according to claim 10 in which the cation is selected from sodium and potassium.

20. The polysaccharide according to claim 11 in which the cation is selected from sodium and potassium.