(S)-(−)-Fluorenylethylchloroformate (FLEC) ; preparation using asymmetric transfer hydrogenation and application to the analysis and resolution of amines

Fluorenylethylchoroformate (FLEC) is a valuable chiral derivatisation reagent that is used for the resolution of a wide variety of chiral amines. Herein, we describe an improved preparation of (S)-(−)-FLEC using an efficient asymmetric catalytic transfer hydrogenation as the key step. We also demonstrate the application of FLEC as a chiral Fmoc equivalent for chiral resolution, with facile deprotection, of tetrahydroquinaldines, and its capacity for inducing regioselective outcomes in nitration reactions

The structure–activity relationships of L3MBTL3 inhibitors: flexibility of the dimer interface

We recently reported the discovery of UNC1215, a potent and selective chemical probe for the L3MBTL3 methyllysine reader domain. In this article, we describe the development of structure-activity relationships (SAR) of a second series of potent L3MBTL3 antagonists which evolved from the structure of the chemical probe UNC1215. These compounds are selective for L3MBTL3 against a panel of methyllysine reader proteins, particularly the related MBT family proteins, L3MBTL1 and MBTD1. A co-crystal structure of L3MBTL3 and one of the most potent compounds suggests that the L3MBTL3 dimer rotates about the dimer interface to accommodate ligand binding

Peptidomimetic techniques and their application in the design and synthesis of Kisspeptin analogues

Peptidomimetic strategies play an important role in the development of peptides as therapeutics and biological probes. Strategies such as cyclisation and the introduction of unusual amino acids are central to the tailoring of peptide‐based compounds which capture the molecular features important for binding, whilst improving stability to proteases. This has the potential to lead to potent and stable peptides which may be used as biological probes or drug candidates. Kisspeptin is a novel peptide hormone which displays anti‐metastatic properties in several tumour types as well as an important role in reproduction. While the study of linear peptide analogues has revealed important features of Kisspeptin, the bioactive conformation is not known. 2D‐NMR structures of Kisspeptins and close Kisspeptin analogues have suggested two preferred conformations, helical and unstructured. This thesis describes the use of peptidomimetic strategies such as cyclisation and the incorporation of unusual amino acids to perform a peptide conformational analysis of Kisspeptin. This is separated into the exploration of the two potential Kisspeptin peptide binding modes – where the active conformation of Kisspeptin is either helical (Chapters 2 and 3) or linear (Chapter 4). Chapter 1 covers the prior literature considered relevant to this thesis. The reader is introduced to the pre‐eminent techniques of peptidomimetic design and the discovery, biological importance and previous work carried out in the field of Kisspeptin‐GPR54. The first body of work presented in this thesis investigates the helix hypothesis by the design of helix stabilised Kisspeptin mimetics. Chapter 2 presents an evaluation of current modelling techniques in the peptidomimetic design of lactam‐bridged peptides is presented and the usefulness and limitations of these methods is described. Chapter 3 presents the synthesis and conformational evaluation of a series of lactam‐bridged Kisspeptin analogues designed to stabilise a helical conformation. With stabilised Kisspeptin analogues in hand, they were evaluated for biological activity at GPR54, giving some useful insights to the bioactive conformation of Kisspeptin. The second body of work presented in this thesis explores the potential use of β-amino acids as a means of increasing stability in the linear analogues. Chapter 4 presents the synthesis and biological evaluation of a β‐amino acid scan of Kisspeptin‐10 and the downsized GPR54 agonist Amb‐Phe‐Gly‐Leu‐Arg‐Phe‐NH2. A series of Boc‐protected β2‐amino acids were synthesised and used for the synthesis of a series of mixed α/β peptides. Peptides were tested GPR54 activity as either a mixture of diastereomers or as separated diastereomers in a functional luciferase assay. The third body of work presented in this thesis describes a new method to facilitate the use of unusual amino acids (such as β2‐amino acids). Chapter 5 investigates the synthesis and application of the chiral pre‐column derivatisation reagent FLEC as a preparative scale separating agent and protecting group in standard Fmoc solid phase peptide synthesis. An efficient synthesis of enantiopure FLEC was devised, employing chiral reduction. Prepared unusual amino acids were protected using (R)‐FLEC and conditions reported for the separation of diastereomers under RP‐HPLC conditions. The use of FLEC as an amine protecting group was demonstrated by the incorporation of FLEC derivatised amino acids in linear peptide sequences under standard Fmoc solid phase synthesis conditions. The final chapter of this thesis (Chapter 6) summarises the achievements that were presented in this body of work

Peptidomimetic techniques and their application in the design and synthesis of Kisspeptin analogues

Peptidomimetic strategies play an important role in the development of peptides as therapeutics and biological probes. Strategies such as cyclisation and the introduction of unusual amino acids are central to the tailoring of peptide‐based compounds which capture the molecular features important for binding, whilst improving stability to proteases. This has the potential to lead to potent and stable peptides which may be used as biological probes or drug candidates. Kisspeptin is a novel peptide hormone which displays anti‐metastatic properties in several tumour types as well as an important role in reproduction. While the study of linear peptide analogues has revealed important features of Kisspeptin, the bioactive conformation is not known. 2D‐NMR structures of Kisspeptins and close Kisspeptin analogues have suggested two preferred conformations, helical and unstructured. This thesis describes the use of peptidomimetic strategies such as cyclisation and the incorporation of unusual amino acids to perform a peptide conformational analysis of Kisspeptin. This is separated into the exploration of the two potential Kisspeptin peptide binding modes – where the active conformation of Kisspeptin is either helical (Chapters 2 and 3) or linear (Chapter 4). Chapter 1 covers the prior literature considered relevant to this thesis. The reader is introduced to the pre‐eminent techniques of peptidomimetic design and the discovery, biological importance and previous work carried out in the field of Kisspeptin‐GPR54. The first body of work presented in this thesis investigates the helix hypothesis by the design of helix stabilised Kisspeptin mimetics. Chapter 2 presents an evaluation of current modelling techniques in the peptidomimetic design of lactam‐bridged peptides is presented and the usefulness and limitations of these methods is described. Chapter 3 presents the synthesis and conformational evaluation of a series of lactam‐bridged Kisspeptin analogues designed to stabilise a helical conformation. With stabilised Kisspeptin analogues in hand, they were evaluated for biological activity at GPR54, giving some useful insights to the bioactive conformation of Kisspeptin. The second body of work presented in this thesis explores the potential use of β-amino acids as a means of increasing stability in the linear analogues. Chapter 4 presents the synthesis and biological evaluation of a β‐amino acid scan of Kisspeptin‐10 and the downsized GPR54 agonist Amb‐Phe‐Gly‐Leu‐Arg‐Phe‐NH2. A series of Boc‐protected β2‐amino acids were synthesised and used for the synthesis of a series of mixed α/β peptides. Peptides were tested GPR54 activity as either a mixture of diastereomers or as separated diastereomers in a functional luciferase assay. The third body of work presented in this thesis describes a new method to facilitate the use of unusual amino acids (such as β2‐amino acids). Chapter 5 investigates the synthesis and application of the chiral pre‐column derivatisation reagent FLEC as a preparative scale separating agent and protecting group in standard Fmoc solid phase peptide synthesis. An efficient synthesis of enantiopure FLEC was devised, employing chiral reduction. Prepared unusual amino acids were protected using (R)‐FLEC and conditions reported for the separation of diastereomers under RP‐HPLC conditions. The use of FLEC as an amine protecting group was demonstrated by the incorporation of FLEC derivatised amino acids in linear peptide sequences under standard Fmoc solid phase synthesis conditions. The final chapter of this thesis (Chapter 6) summarises the achievements that were presented in this body of work

High-resolution US of the facial vessels with new facial vein landmarks for reconstructive surgery and dermal injection

Abstract Background Accurate knowledge of vessel anatomy is essential in facial reconstructive surgery. The technological advances of ultrasound (US) equipment with the introduction of new high-resolution probes improved the evaluation of facial anatomical structures. Our study had these objectives: the primary objective was to identify new surgical landmarks for the facial vein and to verify their precision with US, the secondary objective was to evaluate the potential of high-resolution US examination in the study of both the facial artery and vein. Methods Two radiologists examined a prospective series of adult volunteers with a 22–8 MHz hockey-stick probe. Two predictive lines of the facial artery and vein with respective measurement points were defined. The distance between the facial vein and its predictive line (named mandibular-orbital line) was determined at each measurement point. The distance from the skin and the area of the two vessels were assessed at every established measurement point. Results Forty-one volunteers were examined. The median distance of the facial vein from its predictive line did not exceed 2 mm. The facial vein was visible at every measurement point in all volunteers on the right side, and in 40 volunteers on the left. The facial artery was visible at every measurement point in all volunteers on the right and in 37 volunteers on the left. Conclusions The facial vein demonstrated a constant course concerning the mandibular-orbital line, which seems a promising clinical and imaging-based method for its identification. High-resolution US is valuable in studying the facial artery and vein. Relevance statement High-resolution US is valuable for examining facial vessels and can be a useful tool for pre-operative assessment, especially when combined with the mandibular-orbital line, a new promising imaging and clinical technique to identify the facial vein. Key points • High-resolution US is valuable in studying the facial artery and vein. • The facial vein demonstrated a constant course concerning its predictive mandibular-orbital line. • The clinical application of the mandibular-orbital line could help reduce facial surgical and cosmetic procedure complications. Graphical Abstrac

Structural Determinants for Small-Molecule Activation of Skeletal Muscle AMPK α2β2γ1 by the Glucose Importagog SC4.

The AMP-activated protein kinase (AMPK) αβγ heterotrimer regulates cellular energy homeostasis with tissue-specific isoform distribution. Small-molecule activation of skeletal muscle α2β2 AMPK complexes may prove a valuable treatment strategy for type 2 diabetes and insulin resistance. Herein, we report the small-molecule SC4 is a potent, direct AMPK activator that preferentially activates α2 complexes and stimulates skeletal muscle glucose uptake. In parallel with the term secretagog, we propose "importagog" to define a substance that induces or augments cellular uptake of another substance. Three-dimensional structures of the glucose importagog SC4 bound to activated α2β2γ1 and α2β1γ1 complexes reveal binding determinants, in particular a key interaction between the SC4 imidazopyridine 4'-nitrogen and β2-Asp111, which provide a design paradigm for β2-AMPK therapeutics. The α2β2γ1/SC4 structure reveals an interaction between a β2 N-terminal α helix and the α2 autoinhibitory domain. Our results provide a structure-function guide to accelerate development of potent, but importantly tissue-specific, β2-AMPK therapeutics