Fully Detachable Molecular Umbrellas as Peptide Delivery Agents

A persulfated molecular umbrella, derived from cholic acid and spermidine, has been covalently attached to H-Tyr-d-Ala-Gly-Phe-d-Leu-OH (DADLE) by use of an <i>o</i>-dithiobenzyl carbamate linkage. Treatment of the resulting conjugate (<b>1</b>) with glutathione in solution resulted in the liberation of the free form of the peptide. Addition of <b>1</b> to glutathione-entrapped liposomes, prepared from 1-palmitoyl-2-oleyol-<i>sn</i>-glycero-3-phosphocholine (POPC), 1-palmitoyl-2-oleoyl-<i>sn</i>-glycero-3-phosphatidylglycerol (POPG), and cholesterol [POPC/POPG/cholesterol, 72/4/24 (mol/mol/mol)], resulted in the delivery of DADLE into their aqueous interior.