Disclosed are compositions and methods related to improving pharmacological properties of bioactive compounds targeting nervous system.

Disclosed are compositions and methods related to improving pharmacological properties of bioactive compounds targeting nervous system.

An intracellular selection system allows screening for peptide bioactivity and stability. Randomized recombinant peptides are screened for bioactivity in a tightly regulated expression system, preferably derived from the wild-type lac operon. Bioactive peptides thus identified are inherently protease- and peptidase-resistant. Also provided are bioactive peptides stabilized by a stabilizing group at the N-terminus, the C-terminus, or both. The stabilizing group can be a small stable protein, such as the Rop protein, glutathione sulfotransferase, thioredoxin, maltose binding protein, or glutathione reductase, an -helical moiety, or one or more proline residues.

An intracellular selection system allows screening for peptide bioactivity and stability. Randomized recombinant peptides are screened for bioactivity in a tightly regulated expression system, preferably derived from the wild-type lac operon. Bioactive peptides thus identified are inherently protease- and peptidase-resistant. Also provided are bioactive peptides stabilized by a stabilizing group at the N-terminus, the C-terminus, or both. The stabilizing group can be a small stable protein, such as the Rop protein, glutathione sulfotransferase, thioredoxin, maltose binding protein, or glutathione reductase, an -helical moiety, or one or more proline residues.

The present invention is directed to compounds according to formula,

(R.sup.2R.sup.3)-A.sup.1-c(A.sup.2-A.sup.3-A.sup.4-A.sup.5-A.sup.6-A.sup.7-A.sup.8-A.sup.9)-A.sup.10-R.sup.1,

and pharmaceutically-acceptable salts thereof that act as ligands for one or more of the melanocortin receptors, to methods of using such compounds to treat mammals and to pharmaceutical compositions comprising said compounds.

The present invention is directed to compounds according to formula,

(R.sup.2R.sup.3)-A.sup.1-c(A.sup.2-A.sup.3-A.sup.4-A.sup.5-A.sup.6-A.sup.7-A.sup.8-A.sup.9)-A.sup.10-R.sup.1,

and pharmaceutically-acceptable salts thereof that act as ligands for one or more of the melanocortin receptors, to methods of using such compounds to treat mammals and to pharmaceutical compositions comprising said compounds.

Peptide analogues of dynorphin and their use in pain management, the peptide analogues having good biological stability and reduced side effects compared to opioid analgesics.

Peptide analogues of dynorphin and their use in pain management, the peptide analogues having good biological stability and reduced side effects compared to opioid analgesics.

The invention relates to cyclic peptide agonists that bind to the mu (morphine) opioid receptor and their use in the treatment of acute and/or chronic pain. Embodiments of the invention are directed to cyclic pentapeptide and hexapeptide analogs of endomorphin that have (i) a carboxy-terminal extension with an amidated hydrophilic amino acid and (ii) a substitution in amino acid position 2. These peptide analogs exhibit decreased tolerance relative to morphine, increased solubility compared to similar tetrapeptide analogs, while maintaining favorable or improved therapeutic ratios of analgesia to side effects.

The invention relates to cyclic peptide agonists that bind to the mu (morphine) opioid receptor and their use in the treatment of acute and/or chronic pain. Embodiments of the invention are directed to cyclic pentapeptide and hexapeptide analogs of endomorphin that have (i) a carboxy-terminal extension with an amidated hydrophilic amino acid and (ii) a substitution in amino acid position 2. These peptide analogs exhibit decreased tolerance relative to morphine, increased solubility compared to similar tetrapeptide analogs, while maintaining favorable or improved therapeutic ratios of analgesia to side effects.