The large number of emerging antibody-drug conjugates (ADCs) for cancer therapy has resulted in a significant market ‘boom’, garnering worldwide attention. Despite ADCs presenting huge challenges to ...researchers, particularly regarding the identification of a suitable combination of antibody, linker, and payload, as of September 2021, 11 ADCs have been granted FDA approval, with eight of these approved since 2017 alone. Optimism for this therapeutic approach is clear, despite the COVID-19 pandemic, 2020 was a landmark year for deals and partnerships in the ADC arena, suggesting that there remains significant interest from Big Pharma. Herein we review the enthusiasm for ADCs by focusing on the features of those approved by the FDA, and offer some thoughts as to where the field is headed.
Over the last few decades, design and discovery of chemical reactions that enable modification of proteins at pre-determined sites have been the focus of synthetic organic chemists. As an invaluable ...tool, the site-and chemoselective functionalization of peptides and proteins offers an exciting opportunity for creating high-value multicomponent conjugates with diverse applications in life sciences and pharmacology. In recent years, multiple strategies have emerged that target natural amino acids directly or convert them into other reactive species for further ligations. However, reactivity and selectivity are still key issues in the current state of chemical modification methodologies. Cysteine is one of the least abundant amino acids and exhibits unique chemistry of the thiol or thiolate group which makes it susceptible to a series of post-translational modifications. The thia-Michael "click" addition reactions, which can proceed under facile conditions provide a promising way for thiol-selective modification of cysteine-containing proteins. In this review, we summarize various reactions for cysteine-selective peptide and protein modification, focus on thia-Michael "click" addition reactions, elaborate on their historical perspective and mechanism, and highlight their applications in modifying biomolecules in a site-specific way.
The spiroketal moiety is an important privileged scaffold that occurs extensively in natural products, drugs, and bioactive molecules. Naturally occurring spiroketals are numerous, however aryl-fused ...spiroketals are relatively rare. The only comprehensive review disclosing the isolation, biological activity, and synthesis of benzannulated spiroketal natural products was published nearly a decade ago. This review will serve as an update of the 2009 review and include all known families of benzannulated spiroketals, detailing their isolation and biological activity where relevant. Although not exhaustive, endeavours towards their total synthesis will be discussed.
In the last decade the use of homogenous gold catalysts has rapidly grown and become a valuable tool for complex natural product synthesis. Spiroketal natural products are valuable targets for total ...synthesis and medicinal chemistry applications. The use of gold catalysts has emerged as a useful tool to synthesise these privileged scaffolds. This review summarises the application of gold catalysis for the syntheses of spiro, bridged and fused ketal natural products.
Display omitted
The biological activity and structural diversity of natural products are unsurpassed by any available synthetic screening libraries. As such, these privileged scaffolds serve as ...important, biologically prevalidated platforms for the design of compound libraries in the search for new drug candidates. Recent progress has focussed on improving the potency, selectivity and pharmacokinetics of bioactive natural products through structural modification, leading to the emergence of a number of drug-like lead compounds. Here, we review recent advances in the exploitation of terpenoid, polyketide, phenylpropanoid and alkaloid natural product scaffolds for inspiration in the design and development of important new drug candidates.
The alarming rate at which micro-organisms are developing resistance to conventional antibiotics represents one of the global challenges of our time. There is currently ample space in the ...antibacterial drug pipeline, and scientists are trying to find innovative and novel strategies to target the microbial enemies. Nature has remained a source of inspiration for most of the antibiotics developed and used, and the immune molecules produced by the innate defense systems, as a first line of defense, have been heralded as the next source of antibiotics. Most living organisms produce an arsenal of antimicrobial peptides (AMPs) to rapidly fend off intruding pathogens, and several different attempts have been made to transform this versatile group of compounds into the next generation of antibiotics. However, faced with the many hurdles of using peptides as drugs, the success of these defense molecules as therapeutics remains to be realized. AMPs derived from the proteolytic degradation of the innate defense protein lactoferrin have been shown to display several favorable antimicrobial properties. In an attempt to investigate the biological and pharmacological properties of these much shorter AMPs, the sequence dependence was investigated, and it was shown, through a series of truncation experiments, that these AMPs in fact can be prepared as tripeptides, with improved antimicrobial activity, via the incorporation of unnatural hydrophobic residues and terminal cappings. In this Account, we describe how this class of promising cationic tripeptides has been developed to specifically address the main challenges limiting the general use of AMPs. This has been made possible through the identification of the antibacterial pharmacophore and via the incorporation of a range of unnatural hydrophobic and cationic amino acids. Incorporation of these residues at selected positions has allowed us to extensively establish how these compounds interact with the major proteolytic enzymes trypsin and chymotrypsin and also the two major drug-binding plasma proteins serum albumin and α-1 glycoprotein. Several of the challenges associated with using AMPs relate to their size, susceptibility to rapid proteolytic degradation, and poor oral bioavailability. Our studies have addressed these issues in detail, and the results have allowed us to effectively design and prepare active and metabolically stable AMPs that have been evaluated in a range of functional settings. The optimized short AMPs display inhibitory activities against a plethora of micro-organisms at low micromolar concentrations, and they have been shown to target resistant strains of both bacteria and fungi alike with a very rapid mode of action. Our Account further describes how these compounds behave in in vivo experiments and highlights both the challenges and possibilities of the intriguing compounds. In several areas, they have been shown to exhibit comparable or superior activity to established antibacterial, antifungal, and antifouling commercial products. This illustrates their ability to effectively target and eradicate various microbes in a variety of settings ranging from the ocean to the clinic.
Peptide based hydrogels have received much attention due to their potential biomedical applications. The majority of the gel forming peptides present a β-sheet motif that is composed of alternating ...hydrophobic/hydrophilic amino acids. Furthermore, structural characterization of the assembly of these β-sheet peptides has been refined recently. However, the relationship between peptide residue composition, molecular structure and the mechanical properties of the resulting hydrogel is not entirely understood. In this review, an analysis of the structural features of different β-sheet peptide hydrogels and their mechanical properties is discussed, in order to provide further insight on the molecular features that are relevant for the design of effective β-peptide hydrogels.
The rubromycins are an ever growing family of natural products isolated from various Actinomycetes over the last 60 years. Exhibiting a highly attractive array of antimicrobial and enzyme activity, ...this unique family of compounds have attracted significant attention from many synthetic chemists. Investigations into the synthesis of the densely functionalised hexacyclic ring system have revealed many hidden synthetic challenges. This review covers the isolation, the reported biological activity and the detailed synthetic studies towards these complex natural products.
PDF
