Hydroxyalkyl starch derivatives and process for their preparation

Abstract

The invention relates to a method for the preparation of a hydroxyalkyl starch derivative which comprises reacting hydroxyalkyl starch (HAS) via the optionally oxidised reducing end of the HAS with the amino group M of a crosslinking compound which, apart from the amino group, comprises a specifically protected carbonyl group, namely an acetal group or a ketal group.

1 . A method for the preparation of a hydroxyalkyl starch derivative, comprising
 (i) reacting hydroxyalkyl starch (HAS) of formula (I)   
       
         
           
           
               
               
           
         
         
           via carbon atom C* of the reducing end of the HAS with the amino group M of a crosslinking compound according to formula (II)
   M-L-A  (II)
 
 
           wherein A is an acetal group or a ketal group; and L is a spacer bridging M and A, wherein C* is optionally oxidised prior to the reaction of HAS with M, 
           obtaining a HAS derivative according to formula (III) 
         
       
       
         
           
           
               
               
           
         
         
           
             wherein X is the functional group resulting from the reaction of the amino group M with the HAS via carbon atom C* of the optionally oxidised reducing end of the HAS, and 
             wherein HAS′ is the remainder of the hydroxyalkyl starch molecule, and R 1 , R 2  and R 3  are independently hydrogen or a linear or branched hydroxyalkyl group. 
           
         
       
     
     
         2 . The method of  claim 1 , wherein R 1 , R 2  and R 3  are independently a group —(CH 2 CH 2 O) n —H, wherein n is an integer, preferably 0, 1, 2, 3, 4, 5, or 6. 
     
     
         3 . The method of  claim 1 , wherein the hydroxyalkyl starch is hydroxyethyl starch (HES). 
     
     
         4 . The method of  claim 1 , wherein A is a residue according to formula (IIa) 
       
         
           
           
               
               
           
         
         wherein 
         Z 1  and Z 2  are each independently O or S or NR x , preferably O, wherein R x  is H or lower alkyl such as methyl, ethyl, or propyl such as n-propyl or i-propyl, or C(O)—R y  wherein R y  is preferably selected from the group consisting of C 1 -C 6  alkyl and C 6 -C 14  aryl, even more preferably selected from the group consisting of optionally substituted, preferably non-substituted methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and tert-butyl; R x  preferably being H; 
         A 1  and A 2  are each independently methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, benzyl, 1,1,1-trichloroethyl, nitrobenzyl, methoxybenzyl, ethoxybenzyl, or are forming a ring according to formula (IIb) 
       
       
         
           
           
               
               
           
         
         wherein A 1  and A 2 , taken together, are —(CH 2 ) 2 — or —(CH 2 ) 3 — or —(CH 2 CH(CH 3 ))—, and 
         wherein A 3  is H or methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, pentyl, benzyl, or is forming a ring with the N atom of the amino group M or with a suitable atom comprised in L, A 3  preferably being H. 
       
     
     
         5 . The method of  claim 4 , wherein Z 1  and Z 2  are each O; A 3  is H; and wherein A 1  and A 2  are each ethyl or wherein A 1  and A 2  are forming a ring according to formula (IIb) wherein A 1  and A 2 , taken together, are —(CH 2 ) 2 —. 
     
     
         6 . The method of  claim 1 , wherein the amino group M is a group according to formula (IIc) 
       
         
           
           
               
               
           
         
         wherein Y is either absent or is a chemical moiety selected from the group consisting of 
       
       
         
           
           
               
               
           
         
         wherein G is O or S or NH, and, if present twice, each G is independently O or S or NH, O being preferred, and 
         wherein R′ is H or a hydroxy group or an organic residue selected from the group consisting of alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, aryl, substituted aryl, arylalkyl, substituted arylalkyl, alkylaryl, and substituted alkylaryl; preferably H or an organic residue selected from the group consisting of alkyl and substituted alkyl; more preferably H or alkyl. 
       
     
     
         7 . The method of  claim 1 , wherein the amino group M is H 2 N—, H 2 N—O—, H 2 N—NH—(C═O)—, H 3 C—NH— or H 3 C—NH—O—, preferably H 2 N—, H 2 N—O—, or H 2 N—NH—(C═O)—. 
     
     
         8 . The method of  claim 1 , wherein in (i), HAS is reacted via its oxidised reducing end with the amino group M of the crosslinking compound, M being H 2 N—, and wherein the reaction is carried out at a temperature in the range of from 0 to 80° C., and wherein X is —(C═O)—NH—. 
     
     
         9 . The method of  claim 1 , wherein in (i), HAS is reacted, preferably in an aqueous system, via its non-oxidised reducing end with the amino group M of the crosslinking compound, M being H 2 N—, and wherein the reaction is carried out at a temperature in the range of from 20 to 80° C. at a pH in the range of from 4 to 7, X being —CH═N—. 
     
     
         10 . The method of  claim 9 , wherein in (i), the reaction is carried out in the presence of a reductive agent, preferably NaCNBH 3 , to obtain a HAS derivative, X being —CH 2 —NH—. 
     
     
         11 . The method of  claim 1 , wherein in (i), HAS is reacted, preferably in an aqueous system, via its non-oxidised reducing end with the amino group M of the crosslinking compound, M being H 2 N—O— or H 2 N—NH—(C═O)—, and wherein the reaction is carried out at a temperature in the range of from 5 to 80° C. at a pH in the range of from 4.5 to 6.5, X being —CH═N—O— or —CH═N—NH—(C═O)—. 
     
     
         12 . The method of  claim 1 , wherein L bridging M and A is a spacer comprising at least one structural unit according to formula (IId), preferably consisting of a structural unit according to formula (IId) 
       
         
           
           
               
               
           
         
         wherein L 1  and L 2  are independently from each other H or an organic residue selected from the group consisting of alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, aryl, substituted aryl, arylalkyl, substituted arylalkyl, alkylaryl, substituted alkylaryl, and residues —O—R″ wherein R″ is selected from the group consisting of alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, aryl, substituted aryl, arylalkyl, substituted arylalkyl, alkylaryl, substituted alkylaryl; preferably H or an organic residue selected from the group consisting of alkyl and substituted alkyl; more preferably H or alkyl; more preferably H, 
         wherein n is an integer from 1 to 20, preferably from 1 to 10, more preferably from 1 to 6, more preferably from 1 to 4, more preferably 2. 
       
     
     
         13 . The method of  claim 1 , wherein L is —(CL 1 L 2 ) n -, preferably —(CH 2 ) n —, wherein n is an integer from 1 to 20, preferably from 1 to 10, and wherein, more preferably, L is —CH 2 —CH 2 —. 
     
     
         14 . The method of  claim 1 , wherein L comprises at least one structure unit —(CL 1 L 2 ) n1 -O—(CL 1 L 2 ) n2 -, preferably —(CH 2 ) n1 —O—(CH 2 ) n2  wherein n1 is equal to or different from n2, and wherein the spacer L is preferably linked via —(CL 1 L 2 ) n1 - to the amino group M of the crosslinking compound. 
     
     
         15 . The method of  claim 14 , wherein L is —((CL 1 L 2 -O) m —(CL 1 L 2 )—, preferably —((CH 2 ) 2 —O) m —CH 2 —, wherein m is 1, 2, or 3, more preferably 2 or 3. 
     
     
         16 . The method of any of  claim 1 , wherein L is —(CL 1 L 2 ) n -(C═O)—NH—(CL 1 L 2 ) n -, preferably —(CH 2 ) n —(C═O)—NH—(CH 2 ) n —, wherein each n is, independently from each other, preferably in the range of from 1 to 4, more preferably in the range of from 1 to 3. 
     
     
         17 . The method of  claim 16 , wherein L is selected from the group consisting of
 —(CH 2 ) 3 —(C═O)—NH—(CH 2 ) 3 —; —(CH 2 ) 3 —(C═O)—NH—(CH 2 ) 2 —;   —(CH 2 ) 2 —(C═O)—NH—(CH 2 ) 3 —; and —(CH 2 ) 2 —(C═O)—NH—(CH 2 ) 2 —;   most preferably selected from the group consisting of   —(CH 2 ) 3 —(C═O)—NH—(CH 2 ) 2 —; and —(CH 2 ) 2 —(C═O)—NH—(CH 2 ) 2 —.   
     
     
         18 . The method of  claim 1 , wherein the crosslinking compound M-L-A according to formula (II) is selected from the group consisting of
 H 2 N—(CH 2 ) 2 —CH(OCH 2 CH 3 ) 2 ;   H 2 N—(CH 2 ) 2 —O—(CH 2 ) 2 —O—CH 2 —CH(OCH 2 CH 3 ) 2 ,   H 2 N—(CH 2 ) 2 —(C═O)—NH—(CH 2 ) 2 —CH(OCH 2 CH 3 ) 2 ;   H 2 N—(CH 2 ) 3 —(C═O)—NH—(CH 2 ) 2 —CH(OCH 2 CH 3 ) 2 ;   H 2 N—(CH 2 ) 7 —CH(OCH 2 CH 3 ) 2 ;   H 2 N—O—(CH 2 ) 2 —O—(CH 2 ) 2 —O—CH 2 —CH(OCH 2 CH 3 ) 2 ; and   H 2 N—NH—(C═O)—(CH 2 ) 2 —(C═O)—NH—(CH 2 ) 2 —CH(OCH 2 CH 3 ) 2 ;   
       preferably from the group consisting of
 H 2 N—(CH 2 ) 2 —CH(OCH 2 CH 3 ) 2 ; 
 H 2 N—(CH 2 ) 2 —O—(CH 2 ) 2 —O—CH 2 —CH(OCH 2 CH 3 ) 2 , 
 H 2 N—(CH 2 ) 2 —(C═O)—NH—(CH 2 ) 2 —CH(OCH 2 CH 3 ) 2 ; 
 H 2 N—(CH 2 ) 3 —(C═O)—NH—(CH 2 ) 2 —CH(OCH 2 CH 3 ) 2 ; 
 H 2 N—O—(CH 2 ) 2 —O—(CH 2 ) 2 —O—CH 2 —CH(OCH 2 CH 3 ) 2 ; and 
 H 2 N—NH—(C═O)—(CH 2 ) 2 —(C═O)—NH—(CH 2 ) 2 —CH(OCH 2 CH 3 ) 2 ; 
 
       and more preferably from the group consisting of
 H 2 N—(CH 2 ) 2 —CH(OCH 2 CH 3 ) 2 ; 
 H 2 N—(CH 2 ) 2 —O—(CH 2 ) 2 —O—CH 2 —CH(OCH 2 CH 3 ) 2 , 
 H 2 N—(CH 2 ) 2 —(C═O)—NH—(CH 2 ) 2 —CH(OCH 2 CH 3 ) 2 ; and 
 H 2 N—(CH 2 ) 3 —(C═O)—NH—(CH 2 ) 2 —CH(OCH 2 CH 3 ) 2 . 
 
     
     
         19 . The method of  claim 1 , wherein the crosslinking compound M-L-A according to formula (II) is 1-amino-3,3-diethoxypropane. 
     
     
         20 . The method of  claim 1 , further comprising
 (ii) reacting the HAS derivative according to formula (III) via group A with an amino group of a biologically active agent H 2 N-BA′, via reductive amination, obtaining a HAS derivative according to formula (IV)   
       
         
           
           
               
               
           
         
       
     
     
         21 . The method of  claim 20 , wherein prior to (ii), group A of the HAS derivative according to formula (III) is transformed to the corresponding aldehyde or keto group. 
     
     
         22 . The method of  claim 20 , wherein in (ii), the reaction is carried out, preferably in an aqueous system, in the presence of a reducing agent, preferably NaCNBH 3 , at a temperature in the range of from 0 to 37° C., preferably 0 to 25° C. and a pH in the range of from 3 to 9, preferably from 3 to 7, more preferably from 3 to below 7, and wherein in (ii), the molar ratio of the HAS derivative to the biologically active agent H 2 N-BA′ is from 0.1:1 to 200:1 equivalents, preferably from 1:1 to 50:1 equivalents, based on the number average molecular weight (M n ) of the HAS derivative. 
     
     
         23 . The method of  claim 20 , wherein the biologically active agent H 2 N-BA′ is a peptide, an oligopeptide, a polypeptide, a protein, a functional derivative, fragment or mimetic of the polypeptide or protein, a small molecule compound or an oligonucleotide. 
     
     
         24 . The method of  claim 23 , wherein the protein is erythropoietin (EPO) such as recombinant human EPO (rhEPO), a colony-stimulating factor (CSF) such as G-CSF like recombinant human G-CSF (rhG-CSF), interferon (IFN) such as IFN alpha, IFN beta, IFN gamma like recombinant human IFN alpha (rhIFN alpha) or recombinant human IFN beta (rhIFN beta), factor VII such as recombinant human factor VIIa (rhFVIIa), factor IX such as recombinant human factor IX (rhFIX), growth hormone (GH) such as recombinant human growth hormone (rhGH), Fab fragments such as Fab fragment derived from human immunoglobuline G molecule (hFab), immunoglobuline G such as murine immunoglobuline G (mIgG), glucagon-like peptide-1 (GLP-1), asparaginase such as recombinant asparaginase (rAsparaginase), leptin such as recombinant human leptin (rhLeptin), interleukine-2, interleukine-11, alpha-1-antitrypsin, an antibody, or an antibody fragment, or an alternative protein scaffold. 
     
     
         25 .- 51 . (canceled)