A switch in N-terminal capping of ß-peptides creates novel self-assembled nanoparticles.

Small tripeptides composed entirely of ß3-amino acids have been shown to self-assemble into fibres following acylation of the N-terminus. Given the use of Fmoc as a strategy to initiate self-assembly in α-peptides, we hypothesized that the acyl cap can be replaced by an Fmoc without perturbation to the self-assembly and enable simpler synthetic protocols. We therefore replaced the N-acyl cap for an Fmoc group and herein we show that these Fmoc-protected ß3-peptides produce regular spherical particles, rather than fibrous structures, that are stable and capable of encapsulating cargo. We then demonstrated that these particles were able to deliver cargo to cells without any obvious signs of cytotoxicity. This is the first description of such regular nanoparticles derived from Fmoc-protected ß3-peptides.

Esterase-Mediated Sustained Release of Peptide-Based Therapeutics from a Self-Assembled Injectable Hydrogel.

A synthetic strategy for conjugating small molecules and peptide-based therapeutics, via a cleavable ester bond, to a lipidated ß3-tripeptide is presented. The drug-loaded ß3-peptide was successfully co-assembled with a functionally inert lipidated ß3-tripeptide to form a hydrogel. Quantitative release of lactose from the hydrogel, by the action of serum esterases, is demonstrated over 28 days. The esterase-mediated sustained release of the bioactive brain-derived neurotrophic factor (BDNF) peptide mimics from the hydrogel resulted in increased neuronal survival and normal neuronal function of peripheral neurons. These studies define a versatile strategy for the facile synthesis and co-assembly of self-assembling ß3-peptide-based hydrogels with the ability to control drug release using endogenous esterases with potential in vivo applications for sustained localized drug delivery.

TNFSF14-Derived Molecules as a Novel Treatment for Obesity and Type 2 Diabetes.

Obesity is one of the most prevalent metabolic diseases in the Western world and correlates directly with glucose intolerance and insulin resistance, often culminating in Type 2 Diabetes (T2D). Importantly, our team has recently shown that the TNF superfamily (TNFSF) member protein, TNFSF14, has been reported to protect against high fat diet induced obesity and pre-diabetes. We hypothesized that mimics of TNFSF14 may therefore be valuable as anti-diabetic agents. In this study, we use in silico approaches to identify key regions of TNFSF14 responsible for binding to the Herpes virus entry mediator and Lymphotoxin ß receptor. In vitro evaluation of a selection of optimised peptides identified six potentially therapeutic TNFSF14 peptides. We report that these peptides increased insulin and fatty acid oxidation signalling in skeletal muscle cells. We then selected one of these promising peptides to determine the efficacy to promote metabolic benefits in vivo. Importantly, the TNFSF14 peptide 7 reduced high fat diet-induced glucose intolerance, insulin resistance and hyperinsulinemia in a mouse model of obesity. In addition, we highlight that the TNFSF14 peptide 7 resulted in a marked reduction in liver steatosis and a concomitant increase in phospho-AMPK signalling. We conclude that TNFSF14-derived molecules positively regulate glucose homeostasis and lipid metabolism and may therefore open a completely novel therapeutic pathway for treating obesity and T2D.

1,3-Dichloroacetone: A Robust Reagent for Preparing Bicyclic Peptides.

The chemical synthesis of cyclic peptides is a well-established area of research. This has been further expanded by development of bio-orthogonal reactions that enable access to peptides of greater structural complexity. One approach utilizes 1,3-dichloroacetone to selectively link free cysteine side-chains with an acetone-like bridge via an SN2 reaction. Here, we have used this reaction to dimerize cyclic peptide monomers to create novel bicyclic dimeric peptides. We investigated a range of reaction parameters to identify the optimal dimerization conditions for our model systems. One of the acetone-linked dimeric peptides was analyzed for proteolytic stability in human serum and was observed to still be fully intact after 48 h. This study provides valuable insights into the application of 1,3-dichloroacetone as a tool in the synthesis of complex, multicyclic peptides.