Semicarbazone-based saponin conjugate

1 . A saponin derivative based on a saponin comprising a triterpene aglycone core structure and at least one of a first saccharide chain ‘R 1 ’ and a second saccharide chain ‘R 2 ’ linked to the aglycone core structure, wherein the saponin derivative comprises an aglycone core structure comprising an aldehyde group, wherein the saponin on which the saponin derivative is based is a or bi-desmosidic triterpene saponin belonging to the type of a 12,13-dehydrooleanane with the aldehyde group in position C-23, and wherein the aldehyde group is transformed into a semicarbazone functional group according to formula (I)

wherein:

R 1 and R 2 are independently selected from a monosaccharide, a linear oligosaccharide, and a branched oligosaccharide,

X=O, P, or S, and

Y=NR 3 R 4 , wherein R 3 and R 4 independently represent H, an unsubstituted C1-C10 straight chain, branched or cyclic alkyl, an unsubstituted C2-C10 straight chain, branched or cyclic alkenyl or an unsubstituted C2-C10 straight chain or branched alkynyl, or a covalently bound linker; or

Y=

wherein n and m each are an integer independently selected from 1, 2, or 3,

Z=CH 2 , O, S, P or NR 5 , and

wherein R 5 represents H, an unsubstituted C1-C10 straight chain, branched or cyclic alkyl, an unsubstituted C2-C10 straight chain, branched or cyclic alkenyl, an unsubstituted C2-C10 straight chain or branched alkynyl, or a covalently bound linker, or a maleimide moiety according to formula (II)a or formula (II)b

or an azide moiety according to formula (II)c

wherein o is an integer selected from 0-10, and

W is a group according to formula (III)

wherein U=SH, NH 2 or OH and

p is an integer selected from 0-4.

2 . The saponin derivative according to claim 1 , wherein the saponin on which the saponin derivative is based comprises a glucuronic acid group in a carbohydrate substituent at the C-3beta-OH position of the saponin.

3 . The saponin derivative according to claim 1 ,

wherein:

Y=

n and m each are an integer independently selected from 1, 2 or 3; and

Z=CH 2 , O, S, P or NR 5 ; and

wherein R 5 represents H, an unsubstituted C1-C10 straight chain, branched or cyclic alkyl, an unsubstituted C2-C10 straight chain, branched or cyclic alkenyl or an unsubstituted C2-C10 straight chain or branched alkynyl, or a covalently bound linker, or a maleimide moiety according to formula (II)a or formula (II)b

or an azide moiety according to formula (II)c

wherein o is an integer selected from 0-10 and

W is a group according to formula (III)

wherein U=SH, NH 2 or OH and

p is an integer selected from 0-4.

4 . The saponin derivative according to claim 1 , wherein R 1 is selected from:

GlcA-,

Glc-,

Gal-,

Rha-(1→2)-Ara-,

Gal-(1→2)-[Xyl-(1→3)]-GlcA-,

Glc-(1→2)-[Glc-(1→4)]-GlcA-,

Glc-(1→2)-Ara-(1→3)-[Gal-(1→2)]-GlcA-,

Xyl-(1→2)-Ara-(1→3)-[Gal-(1→2)]-GlcA-,

Glc-(1→3)-Gal-(1→2)-[Xyl-(1→3)]-Glc-(1→4)-Gal-,

Rha-(1→2)-Gal-(1→3)-[Glc-(1→2)]-GlcA-,

Ara-(1→4)-Rha-(1→2)-Glc-(1→2)-Rha-(1→2)-GlcA-,

Ara-(1→4)-Fuc-(1→2)-Glc-(1→2)-Rha-(1→2)-GlcA-,

Ara-(1→4)-Rha-(1→2)-Gal-(1→2)-Rha-(1→2)-GlcA-,

Ara-(1→4)-Fuc-(1→2)-Gal-(1→2)-Rha-(1→2)-GlcA-,

Ara-(1→4)-Rha-(1→2)-Glc-(1→2)-Fuc-(1→2)-GlcA-,

Ara-(1→4)-Fuc-(1→2)-Glc-(1→2)-Fuc-(1→2)-GlcA-,

Ara-(1→4)-Rha-(1→2)-Gal-(1→2)-Fuc-(1→2)-GlcA-,

Ara-(1→4)-Fuc-(1→2)-Gal-(1→2)-Fuc-(1→2)-GlcA-,

Xyl-(1→4)-Rha-(1→2)-Glc-(1→2)-Rha-(1→2)-GlcA-,

Xyl-(1→4)-Fuc-(1→2)-Glc-(1→2)-Rha-(1→2)-GlcA-,

Xyl-(1→4)-Rha-(1→2)-Gal-(1→2)-Rha-(1→2)-GlcA-,

Xyl-(1→4)-Fuc-(1→2)-Gal-(1→2)-Rha-(1→2)-GlcA-,

Xyl-(1→4)-Rha-(1→2)-Glc-(1→2)-Fuc-(1→2)-GlcA-,

Xyl-(1→4)-Fuc-(1→2)-Glc-(1→2)-Fuc-(1→2)-GlcA-,

Xyl-(1→4)-Rha-(1→2)-Gal-(1→2)-Fuc-(1→2)-GlcA-,

Xyl-(1→4)-Fuc-(1→2)-Gal-(1→2)-Fuc-(1→2)-GlcA-, and

derivatives thereof, and

R 2 is selected from:

Glc-,

Gal-,

Rha-(1→2)-[Xyl-(1→4)]-Rha-,

Rha-(1→2)-[Ara-(1→3)-Xyl-(1→4)]-Rha-,

Ara-,

Xyl-,

Xyl-(1→4)-Rha-(1→2)-[R1-(→4)]-Fuc- wherein R1 is 4E-Methoxycinnamic acid,

Xyl-(1→4)-Rha-(1→2)-[R2-(→4)]-Fuc- wherein R2 is 4Z-Methoxycinnamic acid,

Xyl-(1→4)-[Gal-(1→3)]-Rha-(1→2)-4-OAc-Fuc-,

Xyl-(1→4)-[Glc-(1→3)]-Rha-(1→2)-3,4-di-OAc-Fuc-,

Xyl-(1→4)-[Glc-(1→3)]-Rha-(1→2)-[R 6 -(→4)]-3-OAc-Fuc- wherein R 6 is 4E-Methoxycinnamic acid,

Glc-(1→3)-Xyl-(1→4)-[Glc-(1→3)]-Rha-(1→2)-4-OAc-Fuc-,

Glc-(1→3)-Xyl-(1→4)-Rha-(1→2)-4-OAc-Fuc-,

(Ara- or Xyl-)(1→3)-(Ara- or Xyl-)(1→4)-(Rha- or Fuc-)(1→2)-[4-OAc-(Rha- or Fuc-)(1→4)]-(Rha- or Fuc-),

Xyl-(1→3)-Xyl-(1→4)-Rha-(1→2)-[Qui-(1→4)]-Fuc-,

Api-(1→3)-Xyl-(1→4)-[Glc-(1→3)]-Rha-(1→2)-Fuc-,

Xyl-(1→4)-[Gal-(1→3)]-Rha-(1→2)-Fuc-,

Xyl-(1→4)-[Glc-(1→3)]-Rha-(1→2)-Fuc-,

Ara/Xyl-(1→4)-Rha/Fuc-(1→4)-[Glc/Gal-(1→2)]-Fuc-,

Api-(1→3)-Xyl-(1→4)-[Glc-(1→3)]-Rha-(1→2)-[R 7 -(→4)]-Fuc- wherein R 7 is 5-O-[5-O-Ara/Api-3,5-dihydroxy-6-methyl-octanoyl]-3,5-dihydroxy-6-methyl-octanoic acid),

Api-(1→3)-Xyl-(1→4)-Rha-(1→2)-[R 8 -(→4)]-Fuc- wherein R 8 is 5-O-[5-O-Ara/Api-3,5-dihydroxy-6-methyl-octanoyl]-3,5-dihydroxy-6-methyl-octanoic acid),

Api-(1→3)-Xyl-(1→4)-Rha-(1→2)-[Rha-(1→3)]-4-OAc-Fuc-,

Api-(1→3)-Xyl-(1→4)-[Glc-(1→3)]-Rha-(1→2)-[Rha-(1→3)]-4-OAc-Fuc-,

6-OAc-Glc-(1→3)-Xyl-(1→4)-Rha-(1→2)-[3-OAc-Rha-(1→3)]-Fuc-,

Glc-(1→3)-Xyl-(1→4)-Rha-(1→2)-[3-OAc-Rha-(1→3)]-Fuc-,

Xyl-(1→3)-Xyl-(1→4)-Rha-(1→2)-[Qui-(1→4)]-Fuc-,

Glc-(1→3)-[Xyl-(1→4)]-Rha-(1→2)-[Qui-(1→4)]-Fuc-,

Glc-(1→3)-Xyl-(1→4)-Rha-(1→2)-[Xyl-(1→3)-4-OAc-Qui-(1→4)]-Fuc-,

Xyl-(1→3)-Xyl-(1→4)-Rha-(1→2)-[3,4-di-OAc-Qui-(1→4)]-Fuc-,

Glc-(1→3)-[Xyl-(1→4)]-Rha-(1→2)-Fuc-,

6-OAc-Glc-(1→3)-[Xyl-(1→4)]-Rha-(1→2)-Fuc-,

Glc-(1→3)-[Xyl-(1→3)-Xyl-(1→4)]-Rha-(1→2)-Fuc-,

Xyl-(1→3)-Xyl-(1→4)-Rha-(1→2)-[Xyl-(1→3)-4-OAc-Qui-(1→4)]-Fuc-,

Api/Xyl-(1→3)-Xyl-(1→4)-[Glc-(1→3)]-Rha-(1→2)-[Rha-(1→3)]-4OAc-Fuc-,

Api-(1→3)-Xyl-(1→4)-[Glc-(1→3)]-Rha-(1→2)-[Rha-(1→3)]-4OAc-Fuc-,

Api/Xyl-(1→3)-Xyl-(1→4)-[Glc-(1→3)]-Rha-(1→2)-[R 9 -(→4)]-Fuc- wherein R 9 is 5-O-[5-O-Rha-(1→2)-Ara/Api-3,5-dihydroxy-6-methyl-octanoyl]-3,5-dihydroxy-6-methyl-octanoic acid),

Api/Xyl-(1→3)-Xyl-(1→4)-[Glc-(1→3)]-Rha-(1→2)-[R 10 -(→4)]-Fuc- wherein R 10 is 5-O-[5-O-Ara/Api-3,5-dihydroxy-6-methyl-octanoyl]-3,5-dihydroxy-6-methyl-octanoic acid),

Api/Xyl-(1→3)-Xyl-(1→4)-[Glc-(1→3)]-Rha-(1→2)-[R 11 -(→4)]-Fuc- wherein R 11 is 5-O-[5-O-Ara/Api-3,5-dihydroxy-6-methyl-octanoyl]-3,5-dihydroxy-6-methyl-octanoic acid),

Api-(1→3)-Xyl-(1→4)-Rha-(1→2)-[R 12 -(→4)]-Fuc- wherein R 12 is 5-O-[5-O-Ara/Api-3,5-dihydroxy-6-methyl-octanoyl]-3,5-dihydroxy-6-methyl-octanoic acid),

Xyl-(1→3)-Xyl-(1→4)-Rha-(1→2)-[R 13 -(→4)]-Fuc- wherein R 13 is 5-O-[5-O-Ara/Api-3,5-dihydroxy-6-methyl-octanoyl]-3,5-dihydroxy-6-methyl-octanoic acid),

Api-(1→3)-Xyl-(1→4)-Rha-(1→2)-[R 14 -(→3)]-Fuc- wherein R 14 is 5-O-[5-O-Ara/Api-3,5-dihydroxy-6-methyl-octanoyl]-3,5-dihydroxy-6-methyl-octanoic acid),

Xyl-(1→3)-Xyl-(1→4)-Rha-(1→2)-[R 15 -(→3)]-Fuc- wherein R 15 is 5-O-[5-O-Ara/Api-3,5-dihydroxy-6-methyl-octanoyl]-3,5-dihydroxy-6-methyl-octanoic acid)

Glc-(1→3)-[Glc-(1→6)]-Gal-, and

derivatives thereof.

5 . The saponin derivative according to claim 1 , wherein the saponin derivative is a derivative of a saponin selected from the group of saponins consisting of: Quillaja bark saponin, NP-017777, NP-017778, NP-017774, NP-018110, NP-017772, NP-018109, NP-017888, NP-017889, NP-018108, SA1641, AE X55, NP-017674, NP-017810, AG1, NP-003881, NP-017676, NP-017677, NP-017706, NP-017705, NP-017773, NP-017775, SA1657, AG2, SO1861, GE1741, SO1542, SO1584, SO1658, SO1674, SO1832, SO1904, SO1862, QS-7, QS1861, QS-7 api, QS1862, QS-17, QS-18, QS-21 A-apio, QS-21 A-xylo, QS-21 B-apio, and QS-21 B-xylo.

6 . The saponin derivative according to claim 1 , wherein the saponin derivative is according to Molecule (V), Molecule (VII) or Molecule (VIII):

7 . A first pharmaceutical composition comprising the saponin derivative according to claim 1 .

8 . A saponin conjugate based on a saponin derivative according to claim 1 , wherein the aldehyde group is transformed into a semicarbazone group according to formula (IX)

wherein n and m each are an integer independently selected from 1, 2, or 3;

o is an integer selected from 0-10;

and wherein the maleimide group is further transformed into a thioether bond through reaction with a first proteinaceous molecule (‘proteinaceous molecule 1’) comprising a thiol group according to formula (X)

9 . The saponin conjugate according to claim 8 , wherein the proteinaceous molecule 1 comprises a cell-surface molecule binding-molecule comprising a first binding site for binding to a first epitope of a first cell-surface molecule.

10 . The saponin conjugate according to claim 8 , wherein the proteinaceous molecule 1 comprises a covalently bound effector moiety.

11 . The saponin derivative according to claim 1 , wherein the semicarbazone group of formula (I) is hydrolysable under acidic conditions, wherein hydrolysis of said semicarbazone group provides an aldehyde group.