Late stage O-glycosylation: A strategic gateway to complex therapeutic natural products.

Complex natural product production methods and options

The mostly very complex composition of biogen drugs and particularly of combination drug products forces to compromises in the evaluation of their quality and efficacy. These necessary compromises are compatible with the current guidelines of the European Union, provided their reasonable interpretation. The problems occuring on the standardization of complex natural products of vegetable and animal origin do less result from insufficient knowledge of their composition at present, but rather mostly from ignorance of the contribution of their single components to the therapeutically wanted actions in qualitatively and particularly in quantitatively respect. Reasons are frequently methodical deficiencies in older experimental pharmacological and also clinical studies including an insufficient standardization of the tested products, but partly also the fact that due to the multiple ingredients their quantification or even their isolation and their single assay is impossible with justifiable efforts. The necessity of compromises with regard to the standardization of natural drug products results from the exclusive purpose of the quality assurance consisting in the guarantee of constant efficacy and safety of the product with consideration of the respective therapeutical claim as well as from the scientific state of knowledge, which is mostly lower of natural products in comparison to synthetic products. Therefore the requirements on product standardization must not orientate to their principal scientific feasibility, but have to consider the need of safety in the actual case and moreover the therapeutical relevance of the chemical components of the respective natural product. Conclusion for the quality control is that complex mixtures of natural origin with highly active components have to be standardized with defined and close content limits by chemical analytical or biological assays, whereas for natural products with mild active components - and this concerns the majority of them - broader tolerances or only lower limits for the content of the specified components with consideration of the natural fluctuations should be sufficient. Therefore the qualified quality evaluation of complex natural drug products besides a high scientific expertise and the knowledge of the obligative regulations also requires the ability and readiness adequately to interprete these regulations in the sense of a justified claim of safety in the concrete case considering product specific particularities and from an interdisciplinary synopsis.

A Fruitful Decade of Organofluorine Chemistry: New Reagents and Reactions

Nickel-Catalyzed Regiodivergent Asymmetric Cycloadditions of α,β-Unsaturated Carbonyl Compounds

Progress in the chemical sciences has formed the world we live in, both on a macroscopic and on a nanoscopic scale. The last century witnessed the development of high performance materials that interact with humans on many layers, from clothing to construction, from media to medical devices. On a molecular level, natural products and their derivatives influence many biological processes, and these compounds have enormously contributed to the health and quality of living of humans. Although coatings of stone materials with oils or resins (containing natural products) have led to improved tools already millennia ago, in contrast today, natural product approaches to designer materials, that is, combining the best of both worlds, remain scarce. In this Account, we will summarize our recent research efforts directed to the generation of natural product functionalized materials, exploiting the strategy of "copy, edit, and paste with natural products". Natural products embody the wisdom of evolution, and only total synthesis is able to unlock the secrets enshrined in their molecular structure. We employ total synthesis ("copy") as a scientific approach to address problems related to molecular structure, the biosynthesis of natural products, and their bioactivity. Additionally, the fundamental desire to investigate the mechanism of action of natural products constitutes a key driver for scientific inquiry. In an emerging area of relevance to society, we have prepared natural products such as militarinone D that can stimulate neurite outgrowth and facilitate nerve regeneration. This knowledge obtained by synthetic organic chemistry on complex natural products can then be used to design structurally simplified compounds that retain the biological power of the parent natural product ("edit"). This process, sometimes referred to as function-oriented synthesis, allows obtaining derivatives with better properties, improving their chemical tractability and reducing the step count of the synthesis. Along these lines, we have demonstrated that militarinone D can be truncated to yield structurally simplified analogs with improved activity. Finally, with the goal of designing bioactive materials, we have immobilized functionally optimized, neuritogenic natural products ("paste"). These materials could facilitate nerve regeneration, act as nerve guidance conduits, or lead to new approaches in neuroengineering. Based on the surface-adhesive properties of electron-deficient catecholates and the knowledge gathered on neuritogenic natural product derivatives, two mechanistically different design principles have been applied to generate neuritogenic materials. In conclusion, natural products, and their functionally optimized analogs, present a large, mostly untapped reservoir of powerful modulators of biological systems, and their hybridization with materials can lead to new approaches in various fields, from biofilm prevention to neuroengineering.

A practical method for the deoxygenation of α-hydroxyl carbonyl compounds under mild reaction conditions is reported here. The use of cheap and easy-to-handle Na2S·9H2O as the reductant in the presence of PPh3 and N-chlorosuccinimide (NCS) enables the selective dehydroxylation of α-hydroxyl carbonyl compounds, including ketones, esters, amides, imides and nitrile groups. The synthetic utility is demonstrated by the late-stage deoxygenation of bioactive molecule and complex natural products.

Structure-Based Engineering of E. coli Galactokinase as a First Step toward In Vivo Glycorandomization

In evolution, nature has created a variety of secondary metabolites with high chemical and structural diversity. These natural products (NPs) were evolved by nature to exert particular biological functions and to bind to different proteins as substrates and targets. Therefore, it is not surprising that a major fraction of the current drugs on the market are derived from or based on NPs and that NPs are valuable tools for the elucidation of biological processes [1]. Although NPs for decades have served as promising starting points for the discovery of new drugs and biological tools, isolation from their original sources and characterization in medium- and high-throughput approaches is severely hampered by limited amounts and insufficient purity. The total synthesis of NPs in principle offers an alternative route for getting access to pure and well-characterized compounds. In many cases, however, the complexity of NPs is prohibitive to fuel subsequent chemical biology or medicinal chemistry research. A systematic structural classification of natural products (SCONP) reveals that NPs embody only a limited number of different structural scaffolds that can be regarded as privileged [2]. SCONP therefore can serve to inspire new synthetic routes combining classical organic chemistry approaches with combinatorial chemistry methods for the synthesis of NP-inspired compound collections that can be regarded as biologically relevant and prevalidated [3, 4]. The synthesis of NP-like compound collections might provide new compounds with biological properties similar to the guiding NPs. The availability of such compounds and efficient methods for their synthesis allows establishing structure–activity correlations and the synthesis of suitable probes for isolation of target proteins and thereby lays the chemical foundation for subsequent identification of target proteins. Such information is crucial and very valuable because the lack of information about the cellular targets of most NPs hampers drug discovery: it defines a bottleneck in the quest for new drugs and in chemical biology research [5]. Furthermore, the missing information about so-called off-targets that may account for side effects complicates subsequent pharmacological and chemical research [5].

Natural products play a key role in innovative drug discovery. To explore the potential application of natural products and their analogues in pharmacology, total synthesis is a key tool that provides natural product candidates and synthetic analogues for drug development and potential clinical trials. Deconstructive synthesis, namely building new, challenging structures through bond cleavage of easily accessible moieties, has emerged as a useful design principle in synthesizing bioactive natural products. Divergent synthesis, namely synthesizing many natural products from a common intermediate, can improve the efficiency of chemical synthesis and generate libraries of molecules with unprecedented structural diversity. In this review, we will firstly introduce five recent and excellent examples of deconstructive and divergent syntheses of natural products (2021–2023). Then, we will summarize our previous work on the deconstructive and divergent synthesis of natural products to demonstrate the high efficiency and simplicity of these two strategies in the field of total synthesis.

Traditional medicine systems worldwide utilize natural products (NPs), including plant-derived compounds, minerals, and organisms, harnessing their healing potential. NPs offer a rich source of potential drug candidates, driving innovation in drug discovery. Recent breakthroughs have reignited interest in harnessing the therapeutic benefits of natural compounds. Clinical applications of NP-based immunotherapies, such as curcumin and resveratrol in cancer treatment, highlight their diverse pharmacological properties. However, despite these advancements, challenges persist in the clinical implementation of NPs. Issues such as standardization, regulatory approval, and supply sustainability remain significant hurdles. Overcoming these limitations requires a concerted effort to address the complexities of NP drug development. Nevertheless, ongoing research efforts and interdisciplinary collaboration hold promise for advancing NP-based therapeutics, paving the way for the development of innovative treatments for various diseases. In the world of precision medicine, a new chapter unfolds as NPs join the therapeutic journey. The exploration of NPs as sources of bioactive compounds has revealed promising prospects for precision therapeutics in medicine. This article explores the therapeutic potential of NPs within the context of precision medicine. It examines the intricate pathways through which bioactive compounds derived from nature offer tailored therapeutic prospects, emphasizing their role in precision medicine interventions. Exploring the synergy between NPs and precision therapeutics at a molecular level, this article delineates the exciting prospect of customized treatments, signifying a transformative impact on modern medical care. The review article further highlights their potential in tailoring treatments based on individual genetic makeup and disease characteristics. Additionally, it discusses challenges and prospects, addressing issues of sourcing, standardization, scalability, and regulatory considerations to realize the full therapeutic potential of NPs.

Natural products account for more than 50% of all small-molecule pharmaceutical agents currently in clinical use. However, low availability often becomes problematic when a bioactive natural product is promising to become a pharmaceutical or leading compound. Advances in synthetic biology and metabolic engineering provide a feasible solution for sustainable supply of these compounds. In this review, we have summarized current progress in engineering yeast cell factories for production of natural products, including terpenoids, alkaloids, and phenylpropanoids. We then discuss advanced strategies in metabolic engineering at three different dimensions, including point, line, and plane (corresponding to the individual enzymes and cofactors, metabolic pathways, and the global cellular network). In particular, we comprehensively discuss how to engineer cofactor biosynthesis for enhancing the biosynthesis efficiency, other than the enzyme activity. Finally, current challenges and perspective are also discussed for future engineering direction.

Aberrant Ras signaling drives numerous cancers, and drugs to inhibit this are urgently required. This compelling clinical need combined with recent innovations in drug discovery including the advent of biologic therapeutic agents, has propelled Ras back to the forefront of targeting efforts. Activated Ras has proved extremely difficult to target directly, and the focus has moved to the main downstream Ras-signaling pathways. In particular, the Ras-Raf and Ras-PI3K pathways have provided conspicuous enzyme therapeutic targets that were more accessible to conventional drug-discovery strategies. The Ras-RalGEF-Ral pathway is a more difficult challenge for traditional medicinal development, and there have, therefore, been few inhibitors reported that disrupt this axis. We have used our structure of a Ral-effector complex as a basis for the design and characterization of α-helical-stapled peptides that bind selectively to active, GTP-bound Ral proteins and that compete with downstream effector proteins. The peptides have been thoroughly characterized biophysically. Crucially, the lead peptide enters cells and is biologically active, inhibiting isoform-specific RalB-driven cellular processes. This, therefore, provides a starting point for therapeutic inhibition of the Ras-RalGEF-Ral pathway.

Nature, a rich source of bioactive natural products, serves as a massive pool of drug candidates for the pharmaceutical industry. However, the supply of these structurally complex chemicals is costly as most of the natural products are scarce in nature, thus requiring de novo synthesis. The supply chain issue hinders the development of novel therapeutic agents from natural products. Microbial synthesis, based on the expression of biosynthetic genes in a suitable microbial host to produce certain chemicals, is a sustainable strategy to produce complex natural products. However, this strategy requires gaining insights into the biosynthesis of target molecules. Most natural products are biosynthetically unknown or not fully elucidated; thus, the sole application of microbial synthesis strategy to produce a given molecule is challenging. In this review, we highlight a strategy that combines microbial and chemical syntheses to tackle the supply chain issue in developing drugs from natural products. We believe this strategy can revive the drug development pipeline for natural products.

Fungal natural products (NPs) comprise a vast number of bioactive molecules with diverse activities, and among them are many important drugs. However, the yields of fungal NPs from native producers are usually low, and total synthesis of structurally complex NPs is challenging. As such, downstream derivatization and optimization of lead fungal NPs can be impeded by the high cost of obtaining sufficient starting material. In recent years, reconstitution of NP biosynthetic pathways in heterologous hosts has become an attractive alternative approach to produce complex NPs. Here, we present an efficient, cloning-free strategy for the cluster refactoring and total biosynthesis of fungal NPs in Aspergillus nidulans. Our platform places our genes of interest (GOIs) under the regulation of the robust asperfuranone afo biosynthesis gene machinery, allowing for their concerted activation upon induction. We demonstrated the utility of our system by creating strains that can synthesize high-value NPs, citreoviridin (1), mutilin (2), and pleuromutilin (3), with good to high yield and purity. This platform can be used not only for producing NPs of interests (i.e., total biosynthesis) but also for elucidating cryptic biosynthesis pathways.

Baricitinib (Olumiant) is a Janus kinase inhibitor utilized for the management of COVID-19, rheumatoid arthritis, and alopecia areata. It received U.S. Food and Drug Administration approval on May 31, 2018. This work developed a sensitive, rapid, environmentally friendly, and reliable UPLC-MS/MS method for quantifying baricitinib in human liver microsomes, utilized to evaluate the in vitro metabolic stability of baricitinib in HLMs. The StarDrop software, with DEREK and P450 metabolic programs, was employed to detect the structural warnings related to BCB and assess the in silico metabolic lability. The validation of the UPLC-MS/MS approach conformed to U.S. Food and Drug Administration standards for bioanalytical approach validation. The present UPLC-MS/MS method exhibited a wide range of linearity (1.0-3000 ng mL-1) and optimum separation of analytes in an ultra-fast separation time (1 min) and was reproducible and accurate in the absence of human liver microsome matrix effects. Baricitinib and encorafenib (the internal standard) were examined employing an isocratic mobile phase technique on a reversed phase (SB C18) column. This study assessed the accuracy and precision of UPLC-MS/MS methodologies for intra- and inter-day evaluations, which ranged from -1.20% to 8.67% and 0.12% to 11.67%, respectively. The intrinsic clearance of baricitinib was quantified at 27.49 mL min-1 kg-1, while the in vitro half-life was established at 29.50 minutes. In silico analysis proposes that slight structural alterations to the pyrrole ring (88%) and the pyrimidine ring (5%) in drug design may increase safety and metabolic stability related to baricitinib. The evaluation of in silico absorption, distribution, metabolism, excretion, and metabolic stability characteristics for baricitinib is crucial for advancing innovative drug discovery focused on enhancing metabolic stability.