Compositions and methods for delivering agents to the central nervous system

1. A compound of the formula:

where X 1 is a transferrin receptor ligands, X 2 is a glycoside hydrolase, and wherein n and l are each independently an integer from 1 to 100, wherein m and k are each independently an integer from 1 to 4, wherein each instance of Y is independently selected from the group consisting of —N(R 3 )C(═O)—, —C(═O)N(R 3 )—, and —C(R 4 ) 2 —, and wherein:

R 1 , R 2 , and each instance of R 3 are independently selected from the group consisting of hydrogen, C1-6 alkyl, and a nitrogen protecting group;

each instance of R 4 is independently selected from the group consisting of a hydrogen, halogen, acyl, alkyl, alkenyl, alkynyl, carbocyclyl, heterocyclyl, aryl, heteroaryl, —OR A , —N(R A ) 2 , —SR A , —CN, —SCN, —C(═NR A )R A , —C(═NR A )OR A , —C(═NR A )N(R A ) 2 , —C(═O)R A , —C(═O)OR A , —C(═O)N(R A ) 2 , —NO 2 , —NR A C(═O)R A —NR A C(═O)OR A , —NR A C(═O)N(R A ) 2 , —OC(═O)R A , —OC(═O)OR A , —OC(═O)N(R A ) 2 , and a nitrogen protecting group when attached to a nitrogen atom, or two R A groups are joined to form a carbocyclic, heterocyclic, aryl, or heteroaryl ring; and

each instance of R A is independently selected from the group consisting of a hydrogen, acyl, alkyl, alkenyl, alkynyl, carbocyclyl, heterocyclyl, aryl, heteroaryl, a nitrogen protecting group when attached to a nitrogen atom, an oxygen protecting group when attached to an oxygen atom, and a sulfur protecting group when attached to a sulfur atom, or two R A groups are joined to form a heterocyclic ring.

2. The compound of claim 1 , which is of the formula:

3. The compound of claim 1 , wherein the transferrin receptor ligand is transferrin.

4. The compound of claim 3 , where the transferrin is a human transferrin.

5. The compound of claim 1 , wherein the transferrin receptor ligand is an antibody or antigen-binding fragment that selectively binds to the transferrin receptor.

6. The compound of claim 1 , wherein the glycoside hydrolase is a lysozyme.

7. The compound of claim 6 , wherein the lysozyme is a human lysozyme.

8. The compound of claim 1 , wherein the glycoside hydrolase hydrolyzes the β-1,4-glycosidic bond between the N-acetylmuramic acid (NAM) and N-acetylglucosamine (NAG) residues of peptidoglycans.

9. The compound of claim 1 , wherein the glycoside hydrolase hydrolyzes the 1,4-beta-linkages between N-acetyl-D-glucosamine residues in chitodextrins.

10. A compound of the formula:

wherein X 1 is a transferrin receptor ligand, and X 2 is a glycoside hydrolase.

11. A compound of the formula

wherein Tf is transferrin and Lz is lysozyme.

12. A multimeric compound comprising a plurality of covalently linked monomers of the formula as set forth in claim 1 .

13. A composition comprising a plurality of compounds, each of which compounds has a formula as set forth in claim 1 .

14. A method of killing gram-positive bacteria, the method comprising contacting the bacteria with a compound of claim 1 in an amount effective to breakdown the cell wall of the bacteria, thereby killing the bacteria.

15. A method of treating a bacterial infection of the central nervous system (CNS) in a subject, the method comprising

administering to the CNS of the subject the composition of claim 13 in an amount effective for treating a bacterial infection in the CNS.

16. The method of claim 15 wherein the step of administering comprising delivering the composition to the subject intravenously, wherein the compound enters the CNS by crossing the blood-brain-barrier.

17. The method of claim 15 further comprising determining that the bacterial infection caused by a gram-positive bacteria, prior to administering the composition to the subject.

18. The method of claim 17 further comprising obtaining a sample of CNS fluid from the subject and performing an assay to detect the presence of gram-positive bacteria in the CNS fluid.

19. The method of claim 18 , wherein the assay is a Gram stain assay or PCR assay.