Delivery of neuropeptides from the periphery to the brain: Studies with enkephalin

Yoram Shechter, Eli Heldman, Keren Sasson, Tzach Bachar, Mary Popov, Matityahu Fridkin

    Research output: Contribution to journalArticlepeer-review

    6 Scopus citations


    Many peptides with the potential of therapeutic action for brain disorders are not in clinical use because they are unable to cross the blood-brain barrier (BBB) following peripheral administration. We have developed two potential strategies for the delivery of peptides to the brain and demonstrated their feasibility with enkephalins. In the first approach, designated induced reversible lipophilization, Leu/Met Enkephalins were converted to 9-fluorenylmethoxycarbonyl (Fmoc) derived lipophilic prodrug analogues, which undergo slow, spontaneous hydrolysis under physiological conditions, generating the native agonists. In contrast to Enkephalin, Fmoc-Met-Enkephalin was found to facilitate an analgesic effect following intraperitoneal administration in mice. Fmoc-Leu-Enkephalin was not analgesic. In the second approach, Enkephalin was linked to BBB transport vectors through an Fmoc based linker spacer, forming conjugates that slowly release Enkephalin under physiological conditions. A pronounced antinociceptive response was thus obtained following intraperitoneal administration of either cationized-human serum albumin-Fmoc-Enkephalin or polyethylene glycol5-Fmoc-Enkephalin. Derivatives of Enkephalin covalently linked to the same BBB-transport vectors through a stable (nonreversible) chemical bond were not analgesic. In summary, we have demonstrated that lipophilicity can be conferred to hydrophilic peptides to a degree permitting the permeation of the BBB by passive diffusion, without the drawback of agonist inactivation, which is often caused by irreversible derivatization. Similarly, in the second strategy, the conjugation to BBB-permeable vectors overcomes the obstacle of peptide inactivation by releasing the active form in the central nervous system.

    Original languageEnglish
    Pages (from-to)399-406
    Number of pages8
    JournalACS Chemical Neuroscience
    Issue number5
    StatePublished - 19 May 2010


    • Blood-brain barrier
    • Enkephalin
    • Neuropeptide
    • Prodrug
    • Reversible- lypophilization
    • Reversible-conjugation

    ASJC Scopus subject areas

    • Biochemistry
    • Physiology
    • Cognitive Neuroscience
    • Cell Biology


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