Enhancement of peptide cellular uptake

A peptide conjugate of the formula I

• (R—X)n-peptide (I)
• wherein:
• n is from 1 to 10;
• X is
• (a) C═O, when the R—X group is attached to:
• (i) the N-terminus of the peptide, or
• (ii) a side chain of the peptide where the functional group of the side chain to which the R—X group is attached is NH2 or OH;
• or
• (b) O or NH, when the R—X group is attached to
• (i) the C-terminus of the peptide, or
• (ii) a side chain of the peptide where the functional group of the side chain to which the R—X group is attached is COOH or CONH2;
• R is selected from the group consisting of C2-18 alkyl;
• C2-18 alkoxy;
• C2-14 alkylenyl containing one or two double bonds;
• cyclobutyl;
• cyclopentyl;
• cyclohexyl optionally monosubstituted with a C1-5 straight or branched chain alkyl group;
• phenyl optionally monosubstituted with a C1-5 straight or branched chain alkyl group;
• and benzyl, and;
• the peptide is selected from the group consisting of SEQ ID NOS:
• 1, 2, 3, 55, 56, and analogs thereof in which one or more amino acids of SEQ ID NOS:
• 1, 2, 3, 55 or 56 are conservatively substituted with another amino acid.