Better Peptides via Chemical Glycosylation: Somatostatin Analogues Having a Human Complex-Type N-Glycan with Improved Drug Properties.

Somatostatin (somatotropin release-inhibiting factor, SRIF) is a growth hormone inhibitory factor in the form of a 14- or 28-amino acid peptide. SRIF affects several physiological functions through its action on five distinct SRIF receptor subtypes (sst1-5). Native SRIF has only limited clinical applications due to its rapid degradation in plasma. To overcome this obstacle, we have developed glycosylated SRIF analogues that possess not only metabolic stability but also high affinity to all five receptor subtypes by attaching human complex-type oligosaccharides. Such glycosylated SRIF analogues with improved pharmacokinetic profiles could be potent and novel therapeutic drugs for SRIF-related diseases in which several SRIF receptor subtypes are closely involved, and also shed light on new indications. Our results show that chemical glycosylation can be a powerful tool for the development of peptide and protein analogues superior to the original molecules with enhanced drug properties.

Syntheses of structurally-simplified and fluorescently-labeled neovibsanin derivatives and analysis of their neurite outgrowth activity in PC12 cells.

The syntheses of several neovibsanin derivatives were carried out in order to elucidate the simple structure required for displaying neurite outgrowth activity. In addition, a fluorescent probe molecule was synthesized and the analysis of its behavior in the PC12 cell line showed that the neovibsanins accumulate on the outer edge of the cell at the site of formation of prominences.

Total synthesis of (+/-)-neovibsanin B.

(+/-)-Neovibsanin B was synthesized based on a DMI-accelerated intramolecular Diels-Alder reaction followed by oxy-Michael addition-lactonization. The synthetic (+/-)-neovibsanin B induced similar morphological changes in NGF-mediated PC12 cells compared with natural (+)-neovibsanin B.