Role of the guanidine group in the N-terminal fragment of PTH(1–11)

Characteristics of parathyroid hormone-1 receptor agonists and antagonists

Aim: Parathyroid hormone-1 receptor (PTH1R) is a member of B G protein-coupled receptors. The agonistic activation of the PTH1R results in the production and secretion of osteoclast-stimulating cytokines while antagonists may be used to treat bone metastases, hypercalcemia, cachexia and hyperparathyroidism. Results: We built pharmacophore models and investigated the characteristics of PTH1R agonists and antagonists. The agonist model consists of three hydrophobic points, one hydrogen bond acceptor and one positive ionizable point. The antagonist model consists of one hydrogen bond donor and three hydrophobic points. Conclusion: The features of the two models are similar, but the hydrogen bond acceptor, which is the main difference between PTH1R agonists and antagonists, suggests it may be essential for the agonist.

Guanidine Motif in Biologically Active Peptides

In the past decade, guanidines have attracted attention as valuable hydrogen bond-based catalysts while they have long been considered as organic superbases with a broad scope of synthetic applicability. Their easy modification has also expanded their capacity to form complexes with a wide range of metal salts as effective metal scavengers. All these attractive aspects have promoted a huge growth in the field of organic synthesis involving guanidines and examples of such reactions have been collected in numerous reviews and some books. Moreover, this structural motif is also present in a large number of natural products and biologically active compounds that exhibit appealing properties and play important roles in medicinal chemistry. In this highlight, we will only cover the synthesis and properties of biologically active guanidine-containing peptides reported in the past 3 years.

The chemistry and biology of organic guanidine derivatives

The chemistry and biology of organic natural guanidines are reviewed, including the isolation, structure determination, synthesis, biosynthesis and biological activities of alkaloids, non-ribosomal peptides, guanidine-bearing terpenes, polyketides and shikimic acid derivatives from natural sources.

Peptide-peptoid hybrids based on (1-11)-parathyroid hormone analogs

A series of peptide-peptoid hybrids, containing N-substituted glycines, were synthesized based on the H-Aib-Val-Aib-Glu-Ile-Gln-Leu-Nle-His-Gln-Har-NH(2) (Har = Homoarginine) as the parent parathyroid hormone (1-11) analog. The compounds were pharmacologically characterized in their agonistic activity at the parathyroid hormone 1 receptor.