DETAILED DESCRIPTION The present invention describes a series of thysplenin peptide analogs capable of regulating the function of cells of the immune system.
As one aspect, the present invention relates to novel tetrapeptides having the following formula: (I) R-Arg-X-Y-Z-R.
sup.
1 or a pharmaceutically acceptable acid- or base-addition salt thereof, wherein R is H, lower alkyl, acetyl, formyl, lower alkanoyl; X is Pro, dehydro-Pro, hydroxy-Pro, D-Lys, .
alpha.
-methylalanine (Aib), or Lys; Y is a D or L amino acid selected from Ala, Asp, Glu, Gln, Asn, beta Asp, Val, Leu, or Ile; Z is Gly or a D or L amino acid selected from Val, Ala, Leu or Ile; R.
sup.
1 is NR.
sup.
2 R.
sup.
3, wherein R.
sup.
2 and R.
sup.
3 are H or a straight chain or branched alkyl or alkenyl having 1 to 6 carbon atoms, optionally substituted with an aryl group or aryl substituted with either a halogen or a straight chain or branched alkyl or alkenyl having 1 to 6 carbon atoms or wherein R.
sup.
2 and R.
sup.
3 together comprise a cyclic methylene group of 3 to 7 carbon atoms, provided that when X is Lys, and Z is Val, Y is other than Asp, Asn, Ala, Asu, or Glu; and when X is Lys, Y is other than Asp; and when X is Ala and Z is Val, Y is other than Asp.
In another aspect, the present invention relates to novel pentapeptides having the following formula: (II) R.
sup.
4 -Arg-X'-Ala-Y'-Z'-R.
sup.
5 or a pharmaceutically acceptable acid- or base-addition salt thereof, wherein R.
sup.
4 is H, lower alkyl, acetyl, formyl, lower alkanoyl, or des-amino; X' is Pro, dehydro-Pro, hydroxy-Pro, D-Lys, Aib, or Lys; Y' is a D or L amino acid selected from Val, Ile, Leu, Lys, Ala, Asp, Glu, Gln; Z' is a D or L amino acid selected from Tyr, Val, Leu, His, Ala, Phe or Trp; and R.
sup.
5 is OH or NR.
sup.
6 R.
sup.
7, wherein R.
sup.
6 and R.
sup.
7 are H or a straight chain or branched alkyl or alkenyl having 1 to 6 carbon atoms, optionally substituted with an aryl group or aryl substituted with either a halogen or a straight chain or branched alkyl or alkenyl having 1 to 6 carbon atoms or wherein R
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