Glycosphingolipids for use in modulating immune responses
Provided herein are sphingolipid compounds that are useful for activating natural killer T cells. Also provided are methods for treating or preventing a disease or disorder that is treatable by activating the immune system by stimulating natural killer T cells. The compounds are therefore useful for treating or reducing the likelihood of occurrence of an immune diseases and disorders, such as autoimmune diseases or disorders. The compounds may also be used for treating or reducing the likelihood of occurrence of a microbial infection or for treating or reducing the likelihood of occurrence of a cancer in a subject by administering the sphingolipid compounds described herein.
1. A compound having the following structure (I):
or a single stereoisomer, a mixture of stereoisomers, tautomer or pharmaceutically acceptable salt thereof, wherein
A is a sugar moiety;
X is —O—, —S—, —NH—, or —CH 2 —;
is a glycosidic bond;
R 1 is C 5-28 fatty acid chain optionally substituted with one or more substituents selected from the group consisting of hydroxy, halo, —NR a R b , oxo, and C 1-3 lower alkyl, or -L 1 -Q 1 -R 3 ;
R 2 is C 5-19 fatty acid chain optionally substituted with one or more substituents selected from the group consisting of hydroxy, halo, —NR a R b , oxo, and C 1-3 lower alkyl; or -L 2 -Q 2 -R 4 ; ;
R a and R b are the same or different and independently hydrogen, acyl, or alkyl;
R e , is hydroxy; and
R d is hydrogen, or alkyl;
L 1 and L 2 are the same or different and independently C 1-26 alkylene or C 2-26 alkenylene chain optionally substituted with one or more substituents selected from the group consisting of hydroxy, halo, —NR a R b , oxo, and C 1-3 lower alkyl;
Q 1 and Q 2 are the same or different and independently carbocycle or heterocycle; and
R 3 and R 4 are the same or different and independently hydrogen or C 1-28 fatty acid chain optionally substituted with one or more substituents selected from the group consisting of hydroxy, halo, —NR a R b , oxo, and C 1-3 lower alkyl, provided that the compound is not:
2. The compound of claim 1 , wherein the compound has the following structure (Ia):
3. The compound of claim 1 wherein the compound has the following structure (IIa):
or
has the following structure (IIb):
4. The compound of claim 1 wherein X is —O—.
5. The compound of claim 1 , wherein (a) A is a monosaccharide selected from glucose, galactose, mannose, talose, iodose, altrose, gulose, allose, ribose, arabinose, xylose, and lyxose or a derivative thereof; or (b) A is a disaccharide selected from sucrose, lactulose, lactose, maltose, trehalose, and cellobiose or a derivative thereof.
6. The compound of claim 1 , wherein A is
or
A is a galactose derivative represented by
wherein,
R 5 is hydrogen, —OR e , —NR a R b , halo, or C 1-3 lower alkyl; R 6 , R 7 , and R 8 —OR e ;
R 9 and R 10 are the same or different and independently hydrogen or C 1-3 lower alkyl, or R 9 and R 10 together form ═O, ═S or ═NH;
R a and R b are the same or different and independently hydrogen, acyl, or alkyl; and
R e is hydrogen, acyl, alkyl, a monosaccharide or a derivative thereof.
7. The compound of claim 1 , wherein (a) R 2 is C 5-19 alkyl, C 5-15 alkyl, C 9-19 alkyl, C 9-15 alkyl, C 5-19 alkenyl, C 5-15 alkenyl, C 9-19 alkenyl or C 9-15 alkenyl, and wherein R 2 may be optionally substituted with one or more hydroxy; or (b) R 2 is —(CH 2 ) m CH(CH 3 ) 2 , and wherein m is an integer of between 4 and 12; or (c) R 2 is —(CH 2 ) 11 CH(CH 3 ) 2 .
8. The compound of claim 1 , wherein (a) R 1 is C 9-15 alkyl; or C 9-15 alkenyl; and wherein R 1 may be optionally substituted with one or more hydroxy; or (b) wherein R 1 is —(CH 2 ) m CH 3 or —(CH 2 ) m CH(CH 3 ) 2 , wherein m is an integer between 4 and 12; or (c) R 1 is —(CH 2 ) 12 CH 3 or —(CH 2 ) 10 CH(CH 3 ) 2 .
9. The compound of claim 8 wherein R d is hydrogen.
10. The compound of claim 1 having the following structure:
11. A pharmaceutical composition comprising the compound of claim 1 and a pharmaceutically acceptable excipient.
12. A method for activating a natural killer T cell (NKT cell) comprising contacting the NKT cell with the compound of claim 1 .