EntreChem (Spain)

Thanks to the use of a sustainable FeIII-based deep eutectic solvent (DES) as promoter/reaction medium, alkynes were hydrated under bench-type reaction conditions (45 °C, air, absence of co-catalysts or co-solvents). This Fe-DES could be recycled for up to eight consecutives runs in the absence of any VOC solvent (E factor = 10). Furthermore, the Fe-DES is able to promote the efficient formal oxidation of internal alkynes into 1,2-diketones, with the system being recycled up to three consecutive times. More information can be found in the Research Article by A. Presa Soto, V. del Amo, J. García-Álvarez, and co-workers (DOI: 10.1002/chem.202301736).

Abstract Fungal infections are a growing global health concern due to the limited number of available antifungal therapies as well as the emergence of fungi that are resistant to first-line antimicrobials, particularly azoles and echinocandins. Development of novel, selective antifungal therapies is challenging due to similarities between fungal and mammalian cells. An attractive source of potential antifungal treatments is provided by ecological niches co-inhabited by bacteria, fungi and multicellular organisms, where complex relationships between multiple organisms has resulted in evolvement of a wide variety of selective antimicrobials. Here, we characterized several analogs of the one such natural compound, Collismycin A. We show that NR-6226C has antifungal activity against several pathogenicCandidaspecies, includingC. albicansandC. glabrata, whereas it only has little toxicity against mammalian cells. Mechanistically, NR-6226C selectively chelates iron, which is a limiting factor for pathogenic fungi during infection. As a result, NR-6226C treatment causes severe mitochondrial dysfunction, leading to formation of reactive oxygen species, metabolic reprogramming and a severe reduction in ATP levels. Using anin vivomodel for fungal infections, we show that NR-6226C significantly increases survival ofCandida-infectedGalleria mellonellalarvae. Finally, our data indicate that NR-6226C synergizes strongly with fluconazole in inhibition ofC. albicans. Taken together, NR-6226C is a promising antifungal compound that acts by chelating iron and disrupting mitochondrial functions.Importance statementDrug-resistant fungal infections are an emerging global threat, and pan-resistance to current antifungal therapies is an increasing problem. Clearly, there is a need for new antifungal drugs. In this study, we characterized a novel antifungal agent, the Collismycin analog NR-6226C. NR-6226C has a favorable toxicity profile for human cells, which is essential for further clinical development. We unraveled the mechanism of action of NR-6226C and found that it disrupts iron homeostasis and thereby depletes fungal cells of energy. Importantly, NR-6226C strongly potentiates the antifungal activity of fluconazole, thereby providing inroads for combination therapy that may reduce or prevent azole resistance. Thus, NR-6226C is a promising compound for further development into antifungal treatment.

BackgroundMiT-Renal Cell Carcinoma (RCC) is characterized by genomic translocations involving microphthalmia-associated transcription factor (MiT) family members TFE3, TFEB, or MITF. MiT-RCC represents a specific subtype of sporadic RCC that is predominantly seen in young patients and can present with heterogeneous histological features making diagnosis challenging. Moreover, the disease biology of this aggressive cancer is poorly understood and there is no accepted standard of care therapy for patients with advanced disease. Tumor-derived cell lines have been established from human TFE3-RCC providing useful models for preclinical studies.MethodsTFE3-RCC tumor derived cell lines and their tissues of origin were characterized by IHC and gene expression analyses. An unbiased high-throughput drug screen was performed to identify novel therapeutic agents for treatment of MiT-RCC. Potential therapeutic candidates were validated in in vitro and in vivo preclinical studies. Mechanistic assays were conducted to confirm the on-target effects of drugs.ResultsThe results of a high-throughput small molecule drug screen utilizing three TFE3-RCC tumor-derived cell lines identified five classes of agents with potential pharmacological efficacy, including inhibitors of phosphoinositide-3-kinase (PI3K) and mechanistic target of rapamycin (mTOR), and several additional agents, including the transcription inhibitor Mithramycin A. Upregulation of the cell surface marker GPNMB, a specific MiT transcriptional target, was confirmed in TFE3-RCC and evaluated as a therapeutic target using the GPNMB-targeted antibody-drug conjugate CDX-011. In vitro and in vivo preclinical studies demonstrated efficacy of the PI3K/mTOR inhibitor NVP-BGT226, Mithramycin A, and CDX-011 as potential therapeutic options for treating advanced MiT-RCC as single agents or in combination.ConclusionsThe results of the high-throughput drug screen and validation studies in TFE3-RCC tumor-derived cell lines have provided in vitro and in vivo preclinical data supporting the efficacy of the PI3K/mTOR inhibitor NVP-BGT226, the transcription inhibitor Mithramycin A, and GPNMB-targeted antibody-drug conjugate CDX-011 as potential therapeutic options for treating advanced MiT-RCC. The findings presented here should provide the basis for designing future clinical trials for patients with MiT-driven RCC.

BackgroundSarcomas comprise a group of aggressive malignancies with very little treatment options beyond standard chemotherapy. Reposition of approved drugs represents an attractive approach to identify effective therapeutic compounds. One example is mithramycin (MTM), a natural antibiotic which has demonstrated a strong antitumour activity in several tumour types, including sarcomas. However, its widespread use in the clinic was limited by its poor toxicity profile.ResultsIn order to improve the therapeutic index of MTM, we have loaded MTM into newly developed nanocarrier formulations. First, polylactide (PLA) polymeric nanoparticles (NPs) were generated by nanoprecipitation. Also, liposomes (LIP) were prepared by ethanol injection and evaporation solvent method. Finally, MTM-loaded hydrogels (HG) were obtained by passive loading using a urea derivative non-peptidic hydrogelator. MTM-loaded NPs and LIP display optimal hydrodynamic radii between 80 and 105 nm with a very low polydispersity index (PdI) and encapsulation efficiencies (EE) of 92 and 30%, respectively. All formulations show a high stability and different release rates ranging from a fast release in HG (100% after 30 min) to more sustained release from NPs (100% after 24 h) and LIP (40% after 48 h). In vitro assays confirmed that all assayed MTM formulations retain the cytotoxic, anti-invasive and anti-stemness potential of free MTM in models of myxoid liposarcoma, undifferentiated pleomorphic sarcoma and chondrosarcoma. In addition, whole genome transcriptomic analysis evidenced the ability of MTM, both free and encapsulated, to act as a multi-repressor of several tumour-promoting pathways at once. Importantly, the treatment of mice bearing sarcoma xenografts showed that encapsulated MTM exhibited enhanced therapeutic effects and was better tolerated than free MTM.ConclusionsOverall, these novel formulations may represent an efficient and safer MTM-delivering alternative for sarcoma treatment.Graphical abstract

A chemoenzymatic approach has been developed for the preparation of sertraline, an established anti‐depressant drug. Ketoreductases (KREDs) were employed to yield a key chiral precursor. The bioreduction of the racemic tetralone exhibited excellent enantioselectivity (>99 % ee) and diastereomeric ratio (99:1) at 29 % conversion (the maximum theoretical yield is 50 %) after 7 hours. The resulting (S,S)‐alcohol was efficiently oxidized to an enantiopure (S)‐ketone, an immediate precursor of sertraline, by using sodium hypochlorite as oxidant and 2‐azaadamantane N‐oxyl (AZADO) as organocatalyst. Alternative routes aiming at the direct biocatalytic amination using imine reductases and transaminases were unsuccessful.

Phenolic acid decarboxylase from Bacillus subtilis (BsPAD) converts several p-hydroxycinnamic acid derivatives into the corresponding p-hydroxystyrenes, which are considered to be promising bio-bas...

Abstract An enzymatic one‐pot process for asymmetric transformation of prochiral ketoximes into alcohols or amines was developed by sequential coupling of a laccase‐catalyzed deoximation either with a ketone reduction (ketoreductase, KRED) or bioamination (ω‐transaminase, ω‐TA) in aqueous medium. An accurate selection of biocatalysts provided the corresponding products in excellent enantiomeric excesses and overall conversions ranging from 83 to >99 % for alcohols and 70 to >99 % for amines. Likewise, the employment of exclusively 1 % (w/w) of Cremophor®, a polyethoxylated castor oil, as co‐solvent enabled to reach concentrations up to 100 mM in the chiral alcohols cascade.

We previously developed an efficient deletion system for streptomycetes based on the positive selection of double-crossover events using bpsA, a gene for producing the blue pigment indigoidine. Using this system, we removed interfering secondary metabolite clusters from Streptomyces lividans TK24, resulting in RedStrep strains with dramatically increased heterologous production of mithramycin A (up to 3-g/l culture). This system, however, required a time-consuming step to remove the resistance marker genes. In order to simplify markerless deletions, we prepared a new system based on the plasmid pAMR18A. This plasmid contains a large polylinker with many unique restriction sites flanked by apramycin and kanamycin resistance genes and the bpsA gene for selecting a double-crossover event. The utility of this new markerless deletion system was demonstrated by its deletion of a 21-kb actinorhodin gene cluster from Streptomyces lividans TK24 with 30% efficiency. We used this system to efficiently remove the matA and matB genes in selected RedStrep strains, resulting in biotechnologically improved strains with a highly dispersed growth phenotype involving non-pelleting small and open mycelia. No further increase in mithramycin A production was observed in these new RedStrep strains, however. We also used this system for the markerless insertion of a heterologous mCherry gene, an improved variant of the monomeric red fluorescent protein, under the control of the strong secretory signal sequence of the subtilisin inhibitor protein, into the chromosome of S. lividans TK24. The resulting recombinant strains efficiently secreted mCherry into the growth medium in a yield of 30mg/l.

<p>Abstract</p>\n\n<p>A dual ruthenium/ketoreductase catalytic system has been developed for the conversion of β‐ketonitriles into optically active β‐hydroxyamides through an unprecedented hydration/bioreduction cascade process in aqueous medium working in concurrent mode. The ketoreductase‐mediated ketone reduction took place with exquisite stereoselectivity and it was simultaneous to the nitrile hydration promoted by the ruthenium catalyst. The overall transformation occurred: (i) employing commercially and readily available catalytic systems (ii) under mild reaction conditions, (iii) with high degree of conversion and excellent stereoselectivity, and (iv) without the need to isolate intermediates and with high final product yields. This genuine process demonstrates the benefits of combining metal and enzymatic catalysis to tackle the limitations arising from each field.</p>

Abstract A dual ruthenium/ketoreductase catalytic system has been developed for the conversion of β‐ketonitriles into optically active β‐hydroxyamides through an unprecedented hydration/bioreduction cascade process in aqueous medium working in concurrent mode. The ketoreductase‐mediated ketone reduction took place with exquisite stereoselectivity and it was simultaneous to the nitrile hydration promoted by the ruthenium catalyst. The overall transformation occurred: (i) employing commercially and readily available catalytic systems (ii) under mild reaction conditions, (iii) with high degree of conversion and excellent stereoselectivity, and (iv) without the need to isolate intermediates and with high final product yields. This genuine process demonstrates the benefits of combining metal and enzymatic catalysis to tackle the limitations arising from each field.