Covering: up to 2025Elansolids are metabolites isolated from the gliding bacterium Chitinophaga sancti (formerly Flexibacter spec.). The fascinating structures of this type of natural products, as well as their promising biological antibiotic activities, have triggered considerable efforts in the study of elansolids, especially their biosynthesis, which features the formation of highly reactive p-quinone methide intermediates in the enzymatic dehydration-IMDA process. This review focuses on the various aspects of p-quinone methides, including their formation, reactivities (chemical transformations), and applications in total synthesis, all of which are elucidated based on the example of elansolids. By highlighting this particular instance of p-quinone methides, it is shown how nature, namely, the enzymes in the PKS assembly line, could tame this type of highly reactive intermediate. Furthermore, by mimicking the p-quinone methide-mediated IMDA process as observed in biosynthesis, chemists can rationally access various synthetically challenging intermediates, for instance tetrahydroindanes, and utilize them in the total synthesis of the elansolid family.

Targeted RNA delivery with precise spatial and temporal control marks a significant advancement in therapeutic development, offering the potential to reduce drug dosages while minimizing off-target effects. In this study, we present a novel platform that employs superparamagnetic iron oxide nanoparticles (SPIONs) for externally controlled, thermally triggered, organ-specific locked nucleic acid (LNA) release. Our platform technology leverages a newly designed thermosensitive conjugate, based on a thermosensitive linker system that utilizes the thermal sensitivity of the tert-butyloxycarbonyl (Boc) group. This tool ensures stability during systemic circulation while enabling traceless, on-demand drug release at the target site. As a proof of concept, we applied this technology in a disease model of cardiac fibrosis, conjugating SPIONs with an inhibitor of microRNA (miRNA)-21, a key pro-fibrotic regulator. The nanoparticle system was thoroughly characterized for its stability, biocompatibility, and heat-induced release properties in vitro and subsequently validated for biodistribution, toxicology, and therapeutic potential in pre-clinical in vivo models. This innovative SPION-based delivery platform provides a versatile and precise framework for RNA-based therapeutics, with broad translational potential across various disease applications.

New sesquiterpene skeletons are accessible when the geminal dimethyl group in farnesyl pyrophosphate (FPP) is exchanged by small strained rings, specifically cyclopropane, cyclobutane, and oxetane. When these new FPP derivatives are exposed to sesquiterpene synthases, the additional chemical reactivity installed in the strained rings can interact in a unique way with the carbocation intermediates in the active centers of sesquiterpene synthases BcBOT2, PenA, Omp7, and Cop4, which are known to be substrate promiscuous. As such, they can induce rearrangements and ring enlargements, which can yield completely new, previously unknown sesquiterpene carbon skeletons with additional carbon atoms embedded in the (oligo)cyclic backbones. A total of 17 new terpenoids are reported and structurally elucidated, 11 of which have so far unknown unnatural terpene backbones. Besides rearrangements of the small rings, we report on the nucleophilic involvement of the oxygen atom in the oxetane ring during the initial cyclization step. As an additional finding, the oxetane analogues of the two known sesquiterpenes africanene and pentalenene were isolated. Molecular modeling studies revealed that the FPP derivatives are optimally oriented for catalysis within the enzymes' active sites. The simulations unveiled alternative binding poses that facilitate divergent cyclization cascades, ultimately leading to the formation of previously uncharacterized molecular frameworks of sesquiterpenes.

Covering: up to 2026A traditional view regarding enzymes assigns them a markedly low substrate promiscuity. This is based, among other factors, on concepts concerning the evolution of metabolism, which, according to the "patchwork model", assumes that the first enzymes converted a variety of substrates more or less effectively into quite different products and that enzymes then differentiated through evolution and became more substrate selective. Starting from linear oligoprenyl diphosphate precursors, terpene synthases produce oligocyclic terpenes via complex carbocation cascades. It was found that these sometimes exhibit unusual substrate acceptance. Using the example of the fungal sesquiterpene synthase BcBOT2, it is shown that the "terpenome" can be expanded in an unprecedented way, whereby completely new terpene backbones can be generated that nature is usually unable to access, as of today.

Covering: up to 2025S-Adenosylmethionine (SAM) belongs to the class of group-transferring coenzymes, whereby alkyl group transfers, especially electrophilic methylations, on the one hand, and radical reactions, which are characterised by initial H radical abstractions, on the other hand, are predominant. From an evolutionary point of view, these types of reactions are fundamental e.g. in the modification of nucleobases and fatty acids but also in methionine biosynthesis. At which point of chemical and biological evolution did SAM come into play? Since SAM is closely tied to nucleotide biochemistry both structurally and biosynthetically, a discussion linking it to RNA appears to be reasonably. Apart from general overviews of the early evolutionary role of coenzymes and cofactors, the appearance of SAM on the evolutionary stage has only been dealt with superficially so far. This report attempts to achieve such a classification, both prebiotically and biosynthetically within the RNA world theory.

Unspecific peroxygenases (UPOs) catalyze the H2O2-dependent monooxygenation of organic substrates with remarkable regioselectivity and chemoselectivity; however, their application to sterically demanding, non-natural terpene skeletons has remained largely unexplored to date. Here, we present a structure-guided, multiparametric screening pipeline that was used to prioritize 17 structurally distinct UPOs and UPO-like enzymes for the late stage oxyfunctionalization of tricyclic terpenoids previously unknown in nature. These are accessible via BcBOT2-catalyzed cyclization of non-natural farnesyl diphosphate analogs. The computer-aided pre-screening included an evaluation of expression levels, an analysis of the tunnel architecture for substrate access, and hierarchical docking using geometric criteria close to the attack conformation to rank candidate enzymes. Experimental screening of the prioritized enzymes identified productive UPO-substrate combinations with excellent agreement between the docking-based regioselectivity predictions and the product profiles confirmed by GC-MS. MthUPO FuncLib_18 catalyzed an “orchestrated” linear cascade of three consecutive oxidations of a furan sesquiterpenoid, converting it into an α-hydroxylactone—a transformation that mimics the natural oxidative diversification that biosynthetically follows terpene cyclization. Particularly striking was that a single inversion of the stereocenter in the 9a/9b diastereomer pair redirected the regioselectivity of MspUPO-mg133 and ChiUPO-II to opposite sides of the furan ring. This finding thus represents a proof-of-concept for regioselectivity reversal through stereochemical changes in the substrate during UPO-catalyzed terpenoid oxidation. Additionally, we were able to access two structures with tertiary alcohols, difficult to achieve by chemical means. Structural analysis of the newly characterized Monosporascus UPOs revealed a distinct UPO-/UPO-like subgroup defined by an EHR catalytic motif, a shortened α-helix, an elongated loop, and the lowest site hydrophobicity among all characterized UPOs. Molecular dynamics simulations, combined with an analysis of the near-attack-conformations of selected enzyme-substrate complexes, confirmed that only the experimentally observed oxidation positions achieve sustained proximity to the ferryl oxygen of compound I with catalytically suitable approach angles over timescales in the microsecond timescale. This work thus significantly expands both the known sequence-structure space of catalytically competent UPOs and the accessible chemical space of terpenoids as substrates.

Fungal terpene biosynthesis is a vital source of bioactive metabolites. Here, we elucidate the function of BcStc5, a Botrytis cinerea terpene synthase previously linked to abscisic acid (ABA) biosynthesis. Using bioinformatics and heterologous expression, we demonstrate that BcStc5 catalyzes the formation of (4S,5S,7R,10S)-4β,10α-eudesmane-5β,11-diol (1), a dihydroxylated sesquiterpenoid not previously reported in fungi. Mechanistic modeling suggests BcStc5 employs a novel, P450-independent dihydroxylation strategy. We further established a scalable bioproduction platform in Escherichia coli, achieving titers >550 mg/L. This work resolves a long-standing biosynthetic controversy, characterizing BcStc5 as an eudesmanediol synthase rather than the ABA cyclase, settling the controversy over this protein.

The origin of life signifies one of science's most profound mysteries, demanding integrative comprehension from chemistry, biology, and physics. In this review we examine the coupled roles of chemical evolution, biological evolution, gravity and light in shaping the earliest stages of life. We discuss how conditions established by the Big Bang, stellar nucleosynthesis and early planetary environments provided the energetic conditions necessary for the emergence of prebiotic chemistry. Going beyond the geocentric perspective, we explore extraterrestrial chemistry and analyze how gravitational fields and electromagnetic radiation jointly influence molecular stability, reaction kinetics, diffusion and spatial confinement. A central hypothesis advanced here is that planetary gravity constitutes a critical, but underappreciated physical selector in prebiotic evolution. Excessively strong gravity may suppress molecular mobility and dynamic self-organization whereas very weak gravity may prevent the retention, concentration, and stabilization of reactive intermediates. Earth’s gravitational acceleration (∼9.81 m s⁻²) may therefore represent a “sweet spot” regime that optimally balances stability and dynamism. Using illustrative examples from prebiotic reaction networks, vesicle self-organization, osmolarity-driven processes, and early peptide-based catalysis, we discuss how gravity could have shaped the emergence of sustained metabolic networks, molecular surrogates, and protocellular systems. We further extend this framework to later evolutionary transitions, including the role of cytoskeletal elements in overcoming gravitational constraints during the colonization of land. Together, this interdisciplinary synopsis provides evidence for gravity’s role as a continuous physical selector acting from chemical evolution to biological complexity, with implications for planetary habitability and the potential uniqueness of life on Earth.

Using elansolids as a case study, it is demonstrated how nature tames the highly reactive p -quinone methide by controlling its reactivity and conformation in a very efficient manner.

How stable are geranyl and farnesyl halides in water? Given the current increased interest in mimicking terpene synthases, we address this fundamental question by investigating their behaviour with regard to their ability to undergo hydrolysis and cyclisation reactions in the absence of a catalyst or chemical promotor. Some linear terpenoids with leaving groups, such as bromide, appear to have an intrinsic tendency to cyclise. In particular, hydrolysis or cyclisation of the respective water-insoluble bromide analogues by ultrasonic treatment was found to be effective. This technique ensured efficient dispersion of the hydrophobic oil droplets in the aqueous medium. It was found that even with short ultrasonic treatment times, the (2,3-Z)-configured terpenes neryl and Z-farnesyl bromide showed a pronounced tendency to cyclise, which in some cases led to high conversion and high selectivity. In contrast, omitting ultrasonic treatment resulted in a heterogeneous reaction environment, leading to a broader and more complex product spectrum, including the formation of dimeric ethers.

Nickel is a versatile element that plays critical roles in Earth's geological and biological evolution, from the depths of the magmatic mantle to the complexity of prebiotic chemistry. While it is not considered the sole catalyst for the origin of life, recent research suggests that Ni may have had a more profound role than traditionally recognized. This review synthesizes Ni isotope geochemistry, biology, and prebiotic chemistry, exploring how Ni isotope variations offer new insights into magmatic processes, hydrothermal systems, and the cycling of Ni through Earth’s lithosphere and hydrosphere. We summarize the pathways of Ni in oceanic environments, highlighting its influence on biogeochemical cycles and microbial metabolisms that shape global ecosystems. Furthermore, we examine the essential roles of Ni in biological systems, focusing on its function as a catalytic metal in enzymes crucial for nitrogen and carbon cycling. Extending to the prebiotic world, we evaluate Ni's potential in catalyzing life’s earliest chemical reactions, including the polymerization of amino acids and the fixation of CO2, possibly driven by unique metal-ligand interactions. Our comprehensive review positions Ni as a pivotal element across geological timescales and environments, underscoring its relevance to both planetary and biochemical processes.

Three geranylgeranyl pyrophosphate derivatives carrying an ether group at different positions within geranylgeranyl pyrophosphate were employed in biotransformations with five diterpene synthases (CotB2, PvHVS, PaFS, Bnd4 and TXS) derived from plants, bacteria and fungi. A total of six new oxygen-containing diterpenoids were isolated and characterized, deepening our knowledge on the substrate promiscuity of diterpene synthases. In addition, the diterpene synthase PvHVS also accepts an ether derivative of farnesyl pyrophosphate and converts it to the same tetrahydrofuran core as found for the analogous extended GGPP substrate. This result further demonstrates that diterpene synthases also exhibit promiscuity toward truncated unnatural substrates.

Resistance of bacterial pathogens against antibiotics is declared by WHO as a major global health threat. As novel antibacterial agents are urgently needed, we re-assessed the broad-spectrum myxobacterial antibiotic myxovalargin and found it to be extremely potent against Mycobacterium tuberculosis. To ensure compound supply for further development we studied myxovalargin biosynthesis in detail enabling production via fermentation of a native producer. Feeding experiments as well as functional genomics analysis suggested a structural revision, which was eventually corroborated by development of a concise total synthesis. The ribosome was identified as the molecular target based on resistant mutant sequencing and a cryo-EM structure revealed that myxovalargin binds within and completely occludes the exit tunnel, consistent with a mode of action to arrest translation during a late stage of translation initiation. Pharmacokinetic and initial in vivo efficacy studies indicated that myxovalargin and analogues show potential for development as an antibacterial agent.

Sesquiterpene synthases (STSs) enable cationic cascade reactions with farnesyl pyrophosphate (FPP) resulting in an immense variety of oligocyclic sesquiterpenes. Their substrate promiscuity allows access to new sesquiterpene carbon skeletons. We explored the ability of eight STSs to process three distinct synthetic FPP derivatives modified at the central isoprenyl unit. These include the incorporation of a keto group at C7 ("keto"-FPP), the relocation of the olefinic double bond into the methyl group ("iso"-FPP), and the shift of the double bond toward the aliphatic terminus of the FPP backbone and loss of the methyl group at C7 ("nor-iso" FPP). We report the enzymatic production of 18 new terpenoids, including a large variety of new oxaterpenoids. One of these is known as a late stage intermediate in the total synthesis of the sex pheromone periplanone B, which is secreted by females of the American cockroach Periplaneta americana to attract mates. Thus, a formal chemoenzymatic synthesis of this pheromone is disclosed.

The fungal sesquiterpene synthase BcBOT2 shows unique substrate promiscuity. It transforms farnesyl pyrophosphate (FPP) into presilphiperfolan-8 beta-ol via a cationic cascade that is initiated by a (1 -> 11) cyclization. Here, it is shown that BcBOT2 also accepts (2,3-Z)-configured FPP derivatives, which provide terpenoids that result from an initial (1 -> 6) cyclization. "Methyl mapping" was conducted by shifting the position of one or more methyl groups, and it was found that the location of methyl groups has a profound effect on the efficacy of cyclizations. In particular, the shift of the methyl group at C3 to the C2 position has the most profound effect on cyclohexane formation. Molecular modeling studies show that (1 -> 6) cyclization took place due to adopting a different catalytically competent docking pose of FPP derivatives compared to natural FPP within the active site of the BcBOT2, which is mainly due to the (2,3-Z)-configuration. This docking pose leads to a C1-C6 distance shorter (3.3-3.5 & Aring;) than the typical association with a near-attack conformation required for cyclization. Finally, these biotransformation results were benchmarked by a comprehensive study of the "hydrolysis" of eight different FPP derivatives. Under enzyme-free conditions, cyclohexene and cycloheptene terpenoids are formed. The ring size is mainly determined by the position of the methyl group at C6 or C7. The study reveals that in addition to protein engineering, unnatural substrates can also be used to specifically manipulate the mode of cyclization of terpene synthases.

Amide synthases catalyze the formation of macrolactam rings from aniline-containing polyketide-derived seco-acids as found in the important class of ansamycin antibiotics. One of these amide synthases is the geldanamycin amide synthase GdmF, which we recombinantly expressed, purified and studied in detail both functionally as well as structurally. Here we show that purified GdmF catalyzes the amide formation using synthetically derived substrates. The atomic structures of the ligand-free enzyme and in complex with simplified substrates reveal distinct structural features of the substrate binding site and a putative role of the flexible interdomain region for the catalysis reaction.

ChemCatChemVolume 17, Issue 1 e202580102 CoverFree Access Cover Feature: Expanding the "Terpenome": Applications of Unspecific Peroxygenases (UPOs) in Oxidations of Unnatural Terpenoids (ChemCatChem 1/2025) This article relates to: Expanding the "Terpenome": Applications of Unspecific Peroxygenases (UPOs) in Oxidations of Unnatural Terpenoids Henry Struwe, Christopher Grimm, Gerald Dräger, Sascha Beutel, Miguel Alcalde, Andreas Kirschning, Selin Kara, Volume 17Issue 1ChemCatChem First Published online: October 8, 2024 Henry Struwe, Henry StruweSearch for more papers by this authorDr. Christopher Grimm, Dr. Christopher GrimmSearch for more papers by this authorDr. Gerald Dräger, Dr. Gerald DrägerSearch for more papers by this authorProf. Sascha Beutel, Prof. Sascha BeutelSearch for more papers by this authorProf. Miguel Alcalde, Prof. Miguel AlcaldeSearch for more papers by this authorProf. Andreas Kirschning, Prof. Andreas KirschningSearch for more papers by this authorProf. Selin Kara, Prof. Selin KaraSearch for more papers by this author Henry Struwe, Henry StruweSearch for more papers by this authorDr. Christopher Grimm, Dr. Christopher GrimmSearch for more papers by this authorDr. Gerald Dräger, Dr. Gerald DrägerSearch for more papers by this authorProf. Sascha Beutel, Prof. Sascha BeutelSearch for more papers by this authorProf. Miguel Alcalde, Prof. Miguel AlcaldeSearch for more papers by this authorProf. Andreas Kirschning, Prof. Andreas KirschningSearch for more papers by this authorProf. Selin Kara, Prof. Selin KaraSearch for more papers by this author First published: 09 January 2025 https://doi.org/10.1002/cctc.202580102AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookxLinkedInRedditWechat Graphical Abstract The Cover Feature shows the exploration of innovative routes in the late-stage oxidation of terpenoids by combining chemical and enzymatic catalysis to achieve the first successful oxyfunctionalization of complex tricyclic and macrocyclic terpenoids. Novel oxiranes and hemiacetals were formed through epoxidation and hydroxylation catalyzed by unspecific peroxygenases (UPOs), expanding the terpenome and unlocking pathways for bioactive compounds like flavors, fragrances, and APIs. More information can be found in the Research Article by A. Kirschning, S. Kara and co-workers (DOI: 10.1002/cctc.202401414). Dr. Hanna Grimm is acknowledged for the cover design. Volume17, Issue1January 9, 2025e202580102 RelatedInformation

Antimicrobial resistance poses a fundamental global threat, necessitating new strategies for effective therapies. Cystobactamids, a class of antibacterial agents targeting bacterial gyrase and topoisomerase IV, represent a non-traditional chemical scaffold with broad-spectrum activity. For toxicological de-risking, we performed a comprehensive profiling on eukaryotic cells, focusing on cytotoxicity, genotoxicity, and mitochondrial toxicity, demonstrating cellular safety and superoxide scavenging properties. Studies in zebrafish embryos assessed developmental, cardiovascular, and hepatic toxicity, indicating a favorable in vivo safety profile. Metabolism studies revealed glucuronidation and amide bond hydrolysis as key pathways, whereby cystobactamid metabolic stability substantially improved by cobicistat co-treatment. Affinity-based protein profiling identified the cholesterol- and HCV-receptor scavenger receptor class B member 1 (SCARB1) as a primary eukaryotic off-target protein, with cystobactamids shown to inhibit SCARB1´s function, preventing hepatitis C virus pseudoparticle entry into cells. These findings suggest a high therapeutic potential for cystobactamids and highlight SCARB1 as a primary eukaryotic target.

Tubulysins belong to a class of natural products originally isolated from myxobacteria culture and are known to induce cell apoptosis through inhibition of microtubule assembly. Herein, we report the computationally designed, structurally simplified, and first solid‐phase peptide synthesis of novel third‐generation tubulin inhibitors in high yields. These inhibitors are devoid of tubuvaline and tubuphenylalanine fragments previously considered essential for tubulin inhibition activity. The most potent inhibitor contains four fragments arranged from the N terminal to the C terminal as N‐methyl pipecolic acid, isoleucine, valine‐thiazole, and asparagine. The hydrophilic tubulin inhibitors demonstrated significant anticancer activity, with IC 50 values in the low nanomolar range (IC 50 = 13–53 nM) within a 48 hours incubation period across prostate, lung, breast, skin, and cervical cancer cell lines. The synthetic strategy incorporates a simplified valine‐thiazole ring structure, retaining both biological activity and chiral integrity of the molecules. The method enables the synthesis of potent tubulin inhibitors by avoiding multistep synthetic and purification procedures, supporting the inhibitor's applicability for large‐scale synthesis and potential therapeutic development. The structural modifications at the N‐terminal result in the loss of activity from nM to µM range, whereas the C‐terminal modification had minimal impact on the potency.