Enantioselective Synthesis of a Cyclopropane Derivative of Spliceostatin A and Evaluation of Bioactivity

Synthesis of 3-carene-derived nanocellulose/1,3,4-thiadiazole-amide complexes with antifungal activity for plant protection

BACKGROUND

Nanopesticides have been proved to be a powerful and promising tool to solve the issues in agriculture. The purpose of the present study was to develop ecofriendly nanopesticide systems by the strategy of comprehensive utilization of two natural biomass resources (bagasse and turpentine oil) because of their incomparable advantages.

RESULTS

In this research, a series of nanocellulose carriers ETOCN-1-ETOCN-4 (ETOCN, esterified TEMPO-oxidized cellulose nanofibers) with different degrees of substitution were prepared and characterized by Fourier-transform infrared (FTIR), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Then, 21 1,3,4-thiadiazole-amide compounds 8a-8u containing gem-dimethylcyclopropane ring were designed, synthesized and characterized. A preliminary bioassay indicated that compound 8i (R = p-Br Ph) exhibited broad-spectrum antifungal activity against the tested fungi. Furthermore, drug-loading complexes 8i/ETOCN-1-8i/ETOCN-4 were fabricated by integration of nanocellulose-based carriers ETOCN-1-ETOCN-4 with bioactive compound 8i, and the drug-loading capacities, microstructures and sustained-releasing performance of these complexes were also investigated. According to the observation of scanning electron microscopy (SEM) images of complex 8i/ETOCN-2, the small-molecule drug and the carrier formed a well-distributed and compact complex, which led to the excellent drug-loading capacity and sustained-releasing performance in the ethanol/water (1:1, v/v) system.

CONCLUSIONS

Complexes 8i/ETOCN-1-8i/ETOCN-4 deserved further study as the promising candidates for the development of nanopesticides. © 2022 Society of Chemical Industry.

Synthesis of Spirocyclic Cyclopropyl Glycosyl-1-phosphate Analogues

A general methodology allowing the preparation of phosphonylated 1-spirocyclopropyl analogues of glycosyl-1-phosphates is reported. The scope of this reaction has been assessed using various exo-glycals easily obtained from the corresponding pyranoses and furanoses. The cyclopropanation was found to be stereospecific, and the cis/trans selectivity only depends on the E/Z configuration of the starting exo-glycal. The four possible isomers of spirocyclopropyl ribose-1-phosphonate could thus be prepared in a controlled manner, protected and deprotected.

Synthesis and Evaluation of Biological Activities of Bis(spiropyrazolone)cyclopropanes: A Potential Application against Leishmaniasis

This work focuses on the search and development of drugs that may become new alternatives to the commercial drugs currently available for treatment of leishmaniasis. We have designed and synthesized 12 derivatives of bis(spiropyrazolone)cyclopropanes. We then characterized their potential application in therapeutic use. For this, the in vitro biological activities against three eukaryotic models-S. cerevisiae, five cancer cell lines, and the parasite L. mexicana-were evaluated. In addition, cytotoxicity against non-cancerous mammalian cells has been evaluated and other properties of interest have been characterized, such as genotoxicity, antioxidant properties and, in silico predictive adsorption, distribution, metabolism, and excretion (ADME). The results that we present here represent a first screening, indicating two derivatives of bis(spiropyrazolone)cyclopropanes as good candidates for the treatment of leishmaniasis. They have good specificity against parasites with respect to mammalian cells.

Spliceostatins and Derivatives: Chemical Syntheses and Biological Properties of Potent Splicing Inhibitors

Spliceostatins and thailanstatins are intriguing natural products due to their structural features as well as their biological significance. This family of natural products has been the subject of immense synthetic interest because they exhibit very potent cytotoxicity in representative human cancer cell lines. The cytotoxic properties of these natural products are related to their ability to inhibit spliceosomes. FR901564 and spliceostatins have been shown to inhibit spliceosomes by binding to their SF3B component. Structurally, these natural products contain two highly functionalized tetrahydropyran rings with multiple stereogenic centers joined by a diene moiety and an acyclic side chain linked with an amide bond. Total syntheses of this family of natural products led to the development of useful synthetic strategies, which enabled the synthesis of potent derivatives. The spliceosome modulating properties of spliceostatins and synthetic derivatives opened the door for understanding the underlying spliceosome mechanism as well as the development of new therapies based upon small-molecule splicing modulators. This review outlines the total synthesis of spliceostatins, synthetic studies of structural derivatives, and their bioactivity.

Synthesis, antifungal activity and 3D-QSAR study of novel acyl thiourea compounds containing gem-dimethylcyclopropane ring

A series of novel acyl thiourea compounds containing gem-dimethylcyclopropane ring were designed and synthesized by multi-step reactions in search of novel antifungal molecules. Structures of all the target compounds were characterized by spectral techniques of UV-vis, FT-IR, ¹H-NMR, ¹³C-NMR, and ESI-MS. The antifungal activity of the target compounds was preliminarily evaluated by agar dilution method. The antifungal bioassay revealed that, at 50 μg/mL, compounds 5h (R = o-F), 5m (R = p-Br), and 5n (R = o-NO₂) showed the same antifungal activity of 73.6% against Physalospora piricola, which was comparable than that of the positive control. Furthermore, against Gibberella zeae, compounds 5k (R = m-Cl), 5l (R = m-Br), 5m (R = p-Br), and 5n (R = o-NO₂) displayed the same antifungal activity of 75.6%, and compound 5o (R = p-NO₂) displayed antifungal activity of 78.8%, which were all better than that of the positive control. The preliminary analysis of 3D-QSAR model was performed to study the effect of molecular structure on biological activity using the comparative molecular field analysis (CoMFA) method. The results showed 3D-QSAR model (r² = 0.995, q² = 0.503) was reasonable and effective.

A Comprehensive Overview of Structure-Activity Relationships of Small-Molecule Splicing Modulators Targeting SF3B1 as Anticancer Agents

The pre-mRNA splicing factor SF3B1 shows recurrent mutations among hematologic malignancies and some solid tumors. In 2007, the identification of two cytotoxic natural products, which showed splicing inhibition by binding to SF3b, prompted the development of small-molecule splicing modulators of SF3B1 as therapeutics for cancer. Recent studies suggested that spliceosome-mutant cells are preferentially sensitive to pharmacologic splicing modulation; therefore, exploring the clinical utility of splicing modulator therapies in patients with spliceosome-mutant hematologic malignancies who have failed current therapies is greatly needed, as these patients have few treatment options. H3B-8800 had unique pharmacological activity and exhibited favorable data in phase I clinical trials to treat patients with advanced myeloid malignancies, indicating that further clinical trials are promising. The most established small-molecule modulators of SF3B1 can be categorized into three classes: the bicycles, the monopyranes, and the 12-membered macrolides. This review provides a comprehensive overview of the structure-activity relationships of small-molecule SF3B1 modulators, with a detailed analysis of interactions between modulators and protein binding pocket. The future strategy for splicing modulators development is also discussed.

Total Synthesis of Meayamycin and O-Acyl Analogues

A short, scalable total synthesis of meayamycin is described by an approach that entails a longest linear sequence of 12 steps (22 steps overall) from commercially available chiral pool materials (ethyl l-lactate, BocNH-Thr-OH, and d-ribose) and introduces the most straightforward preparation of the right-hand subunit detailed to date. The use of the approach in the divergent synthesis of a representative series of O-acyl analogues is exemplified.

Design and Synthesis of 1,2-Deoxy-pyranose Derivatives of Spliceostatin A toward Prostate Cancer Treatment

We designed and synthesized a novel 1,2-deoxy-pyranose and terminal epoxide methyl substituted derivatives of spliceostatin A using Julia-Kocienski olefination as a key step. With respect to the biological activity, the 1,2-deoxy-pyranose analogue of spliceostatin A suppressed AR-V7 expression at the nano level (IC₅₀ = 3.3 nM). In addition, the in vivo toxicity test showed that the 1,2-deoxy-pyranose analogue was able to avoid severe toxicity compared to spliceostatin A.

Copper-Catalyzed Stille Cross-Coupling Reaction and Application in the Synthesis of the Spliceostatin Core Structure

An efficient palladium-free Stille cross-coupling reaction of allylic bromides and functionalized organostannylfuran using catalytic copper halide has been developed. The coupling reaction was optimized using CuI and low catalyst loading (down to 5 mol %). The reaction was conveniently carried out at ambient temperature in the presence of inorganic base to afford the coupling product in good-to-excellent yields. The utility of this reaction was demonstrated in the synthesis of a furan with sensitive functionalities. A sulfolene moiety was utilized as a masking group for the sensitive diene. Noyori asymmetric reduction, Achmatowicz reaction, and Kishi reduction steps converted sulfolene to a highly substituted tetrahydropyran intermediate used in the synthesis of the highly potent antitumor agents, spliceostatins, and their derivatives.