Optimised synthesis of a nitroCBI hypoxia-activated prodrug with substantial anticancer activity

An optimised synthesis of a hypoxia-activated anticancer prodrug related to the duocarmycin family of natural products is described. The improved 10-step synthesis increases the overall yield from 4.4% to over 40% while requiring just 2 chromatography-based purifications. The most significant improvements optimise the isomer distribution in a key chlorosulfonylation reaction, and facilitate the removal of tin residues from a tributyltin hydride-mediated radical reaction. Improved preparations of two side chains are also reported. The new method provides practical access to sufficient material to support advanced efficacy and toxicology assessments.     

A probabilistic approach to classifying metabolic stability

Metabolic stability is an important property of drug molecules that should-optimally-be taken into account early on in the drug design process. Along with numerous medium- or high-throughput assays being implemented in early drug discovery, a prediction tool for this property could be of high value. However, metabolic stability is inherently difficult to predict, and no commercial tools are available for this purpose. In this work, we present a machine learning approach to predicting metabolic stability that is tailored to compounds from the drug development process at Bayer Schering Pharma. For four different in vitro assays, we develop Bayesian classification models to predict the probability of a compound being metabolically stable. The chosen approach implicitly takes the "domain of applicability" into account. The developed models were validated on recent project data at Bayer Schering Pharma, showing that the predictions are highly accurate and the domain of applicability is estimated correctly. Furthermore, we evaluate the modeling method on a set of publicly available data.     

A versatile prodrug approach for liposomal core-loading of water-insoluble camptothecin anticancer drugs

We describe a versatile prodrug strategy for loading the liposomal lumen with water-insoluble camptothecins. The procedure involves conversion of an active camptothecin analogue to a 20-OR omega-aminoalkanoanic ester prodrug in which R = CO[CH(2)](n)()NH(2) and n = 1-3. The basic amino group of the prodrug serves three roles. First, at pH ranges of 3-5, the amine enhances aqueous solubility. Second, it enhances responsiveness to a transmembrane ammonium sulfate gradient across the liposomal bilayer, thereby facilitating active loading of the agent into the liposomal aqueous core. Third, at a physiological pH of 7 or above (the pH to be encountered following drug release at the tumor site), the nucleophilicity of the amine manifests itself and cyclization to the C-21 carbonyl carbon occurs. This cyclization triggers a rapid and convenient nonenzymatic decomposition process that releases active camptothecin. Accordingly, this novel liposomal approach offers a potential system for tumor-targeting prodrugs of many water-insoluble camptothecins, including the highly lipophilic and clinically attractive analogues SN-38, 9-nitrocamptothecin and DB-67. The rate of formation of the active agent at the tumor site can be controlled through the selection of n (the length of the alkyl spacer group).     

Targeting self-enhanced ROS-responsive artesunatum prodrug nanoassembly potentiates gemcitabine activity by down-regulating CDA expression in cervical cancer

Prodrug self-delivery carriers with targeting that specifically responded to tumor microenvironments have good potential to improve the application dilemma of approved clinical therapeutic drugs (systemic distribution and side effects). It's noted the conversion of gemcitabine (GEM) to inactive ingredients under the action of cytidine deaminase (CDA) during metabolism in vivo limits its clinical effect. A high level of reactive oxygen species (ROS) results in a high level of oxidative stress in tumor cells, which changes the expression of CDA and optimizes the metabolism of GEM in vivo and overcome drug resistance. In this study, the ROS responsive and ROS self-supplied prodrug of artemisia (ART)-thioacetal bond (TK)-GEM was synthesized and self-vectors based on ART-TK-GEM (TK@FA NPs) was prepared by using nano precipitation. ROS responsive characteristics ensure specific release of prodrugs in tumor cells with high level of ROS thereby reducing side effects on normal cells and tissues. The endogenous ROS and newly generated ROS by ART can reduce the expression of CDA and optimizes the metabolism of GEM, and the accumulated ROS can also induce apoptosis of tumor cells, realizing synergistic anti-tumor effect of chemical drugs and traditional Chinese medicines. This paper proposes a simple method by using clinically approved drugs to improve the insufficient effect of existing chemotherapy and overcome resistance, which has potential to appropriately shorten the drug development cycle and accelerate the clinical investigation of drugs.     

Albumin-targeting of an oxaliplatin-releasing platinum(iv) prodrug results in pronounced anticancer activity due to endocytotic drug uptake in vivo

Oxaliplatin is a very potent platinum(ii) drug which is frequently used in poly-chemotherapy schemes against advanced colorectal cancer. However, its benefit is limited by severe adverse effects as well as resistance development. Based on their higher tolerability, platinum(iv) prodrugs came into focus of interest. However, comparable to their platinum(ii) counterparts they lack tumor specificity and are frequently prematurely activated in the blood circulation. With the aim to exploit the enhanced albumin consumption and accumulation in the malignant tissue, we have recently developed a new albumin-targeted prodrug, which supposed to release oxaliplatin in a highly tumor-specific manner. In more detail, we designed a platinum(iv) complex containing two maleimide moieties in the axial position (KP2156), which allows selective binding to the cysteine 34. In the present study, diverse cell biological and analytical tools such as laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS), isotope labeling, and nano-scale secondary ion mass spectrometry (NanoSIMS) were employed to better understand the in vivo distribution and activation process of KP2156 (in comparison to free oxaliplatin and a non-albumin-binding succinimide analogue). KP2156 forms very stable albumin adducts in the bloodstream resulting in a superior pharmacological profile, such as distinctly prolonged terminal excretion half-life and enhanced effective platinum dose (measured by ICP-MS). The albumin-bound drug is accumulating in the malignant tissue, where it enters the cancer cells via clathrin- and caveolin-dependent endocytosis, and is activated by reduction to release oxaliplatin. This results in profound, long-lasting anticancer activity of KP2156 against CT26 colon cancer tumors in vivo based on cell cycle arrest and apoptotic cell death. Summarizing, albumin-binding of platinum(iv) complexes potently enhances the efficacy of oxaliplatin therapy and should be further developed towards clinical phase I trials.

Albumin-targeting of a maleimide-containing oxaliplatin-releasing platinum(iv) prodrug results in tumor-specific drug delivery and activity as shown by LA-ICP-MS, isotope-labeling and NanoSIMS in cell culture and in vivo.     

Naphthalenediimide dimers and trimers form self-assembling hydrogen-bonded nanotubes of enhanced stability

Covalent linkage of amino acid-functionalised naphthalenediimides (NDIs) produced a dimer and a trimer that form helical, hydrogen-bonded nanotubes in CHCl₃ solutions and that are more resistant than an analogous monomer to the hydrogen-bond disrupting effects of tetrahydrofuran, methanol and heat.     

Synthesis of betulinic acid acyl glucuronide for application in anticancer prodrug monotherapy

The synthesis of 28-O-β-d-glucuronide betulinic acid, an acyl glucuronide derivative, was successfully carried out for the first time using commercially available peracetylated methyl glucuronate bromide under phase-transfer conditions. The target compound could be used in an anticancer prodrug monotherapy (PMT) strategy since it is non-cytotoxic, non-haemolytic, more water soluble than betulinic acid, it possesses a good in vitro stability in phosphate buffer and can be hydrolyzed in the presence of β-d-glucuronidase releasing in vitro betulinic acid, a promising anticancer agent.     

Enhanced hydrolytic stability of self-assembling alkylated two-dimensional covalent organic frameworks

The stability and bulk properties of two-dimensional boronate ester-linked covalent organic frameworks (COFs) were investigated upon exposure to aqueous environments. Enhanced stability was observed for frameworks with alkylation in the pores of the COF compared to nonalkylated, bare-pore frameworks. COF-18? and COF-5 were analyzed as "bare-pore" COFs, while COF-16? (methyl), COF-14? (ethyl), and COF-11? (propyl) were evaluated as "alkylated-pore" materials. Upon submersion in aqueous media, the porosity of alkylated COFs decreased ～25%, while the nonalkylated COFs were almost completely hydrolyzed, virtually losing all porosity. Similar trends were observed for the degree of crystallinity for these materials, with ～40% decrease for alkylated COFs and 95% decrease for nonalkylated COFs. SEM was used to probe the particle size and morphology for these hydrolyzed materials. Stability tests, using absorbance spectroscopy and (1)H NMR, monitored the release of monomers as the COF degraded. While nonalkylated COFs were stable in organic solvent, hydrolysis was rapid in aqueous environments, more so in basic compared to neutral or acidic aqueous media (minutes to hours, respectively). Notably, alkylation in the pores of COFs slows hydrolysis, exhibiting up to a 50-fold enhancement in stability for COF-11? over COF-18?.     

Interaction of an anticancer drug, gemcitabine, with phospholipid bilayers

The molecular interaction between gemcitabine, an anticancer pyrimidine analogue, and fully hydrated phospholipid (1,2-dipalmitoyl-sn-3-phosphatidylcholine, DPPC) membrane model has been investigated by Differential Scanning Calorimetry (DSC) and Small and Wide Angle X-ray Diffraction (SWAXS). The behaviour of the charged and uncharged forms of gemcitabine has been examined. Our results show that: (1) at physiological pH, gemcitabine does not modify significantly the thermal and structural properties of DPPC, (2) at pH of 2.4 the drug interacts electrostatically with the polar headgroups, inducing the formation of unilamellar vesicles and (3) at acidic pH the DPPC lamellar phase is recovered when salt is added.     

Nitrogen-doped graphene supporting PtSn nanoparticles with a tunable microstructure to enhance the activity and stability for ethanol oxidation

In this work, a series of nitrogen-doped graphenes (NGs) were prepared by deriving from pyrolysis of graphite oxide (GO) with urea at different temperatures and high-dispersed PtSn nanoparticles with tunable size were then deposited onto nitrogen-doped graphene (PtSn/NG) by an easy-controlled template-free method. The PtSn/NG and undoped graphene (PtSn/G) were carried out as anode catalysts for the electrooxidation of ethanol. The microstructure and morphology of the synthesized catalysts were characterized by transmission electron microscopy, X-ray powder diffraction, and X-ray photoelectron spectroscopy. The electrocatalytic performance toward ethanol oxidation was evaluated by cyclic voltammetry and chronoamperometry. It is found that the pyrolysis temperature is an important factor which influenced the contents of nitrogen and functional groups of nitrogen. And then, the functional groups of nitrogen affect the distribution, size, and contents of PtSn nanoparticles. The as-obtained optimal PtSn/NG-600 sample with narrower size distribution and high content of PtSn exhibits higher electrocatalytic activity and stability compared with the other samples, implying the potential application for ethanol fuel cells.     

PARP抑制剂的虚拟筛选、酶抑制活性及代谢稳定性研究

聚腺苷酸二磷酸核糖聚合酶（Poly-ADP-ribose polymerase, PARP）通过“合成致死”效应对携带BRCA突变的患者疗效显著,现已成为癌症治疗的重要靶点。多款PARP抑制剂已批准上市,极大的改善了当前卵巢癌的治疗现状,但其耐药性与低亚型选择性受到了研究人员的广泛关注。本研究采用虚拟筛选和生物活性实验验证,发现化合物Y041-8647对PARP的酶抑制活性IC50 值为1.4 μM。体外代谢稳定性研究表明,Y041-8647在人工胃肠液、血浆及体外肝微粒体中稳定性良好。此外,本研究通过分子动力学揭示了Y041-8647与7KK5蛋白的相互作用模式。本研究中化合物Y041-8647可作为进一步改造的先导化合物,为新型PARP抑制剂的开发提供了新的思路。     

A self-assembling peptide targeting VEGF receptors to inhibit angiogenesis

Vascular endothelial growth factor (VEGF)-vascular endothelial growth factor receptor (VEGFR) pathways are essential in tumor angiogenesis, growth and metastasis. Studies on anti-angiogenic therapy have been mostly focused on the blockage of VEGF-VEGFR pathways. We report an extracellularly transformable peptide-based nanomaterial to develop artificial extracellular matrix (ECM)-like networks for high-efficient blockage of natural VEGF-VEGFR interactions. The transformable peptide-based nanomaterial transforms from nanoparticles into nanofibers upon binding to VEGFR in solution. In addition, the transformable peptide-based nanomaterial forms ECM-like fibrous networks on VEGFR overexpressed cells, inhibiting the VEGF-VEGFR interactions and the subsequent angiogenesis. The tube formation is reduced by nearly 85.1% after treatment. This strategy shows excellent potential for anti-angiogenesis, and inhibition of tumor invasion and metastasis.     

A self-assembling peptide targeting VEGF receptors to inhibit angiogenesis

Vascular endothelial growth factor (VEGF)-vascular endothelial growth factor receptor (VEGFR) pathways are essential in tumor angiogenesis, growth and metastasis. Studies on anti-angiogenic therapy have been mostly focused on the blockage of VEGF-VEGFR pathways. We report an extracellularly transformable peptide-based nanomaterial to develop artificial extracellular matrix (ECM)-like networks for high-efficient blockage of natural VEGF-VEGFR interactions. The transformable peptide-based nanomaterial transforms from nanoparticles into nanofibers upon binding to VEGFR in solution. In addition, the transformable peptide-based nanomaterial forms ECM-like fibrous networks on VEGFR overexpressed cells, inhibiting the VEGF-VEGFR interactions and the subsequent angiogenesis. The tube formation is reduced by nearly 85.1% after treatment. This strategy shows excellent potential for anti-angiogenesis, and inhibition of tumor invasion and metastasis.     

Radioiodination and preliminary biological tests of aniline-mustard and its glucuronide conjugate as a potential anticancer prodrug

Aniline-mustard and its glucuronide conjugate were radioiodinated with ¹³¹I. The preliminary dynamic tests were carried out on rabbits. The scintigrams showed clearly that the glucuronide conjugate of aniline-mustard was very quickly cleared from the metabolism, accumulating in the bladder in about 15 minutes. The clearance time of radioiodinated aniline-mustard-glucuronide was considerably longer (about 45 min.). The results obtained from the biodistributional studies have represented interesting differences between the metabolic details of radioiodinated compounds, and indicated that the glucuronide conjugate of aniline-mustard may be a promising radioiodinated prodrug, if verification of its selective accumulation in some kinds of tumor cells can be obtained.     

Synthesis and anticancer activity of benzotriazole derivatives

A series of benzotriazole (BTA) derivatives were synthesized as tyrosine protein kinase inhibitors using fragment-based design strategy. All desired compounds were synthesized with the reaction of benzotriazole, chloroacetonitrile and aromatic aldehyde using Ultrasonic-Microwave method and characterized by IR, ¹H and ¹³C-NMR, mass spectrometry (MS) and elemental analysis. The anticancer activity of these compounds was evaluated by CCK-8 method against carcinoma VX2, lung cancer A549, stomach cancer cell lines MKN45 and MGC in vitro. The results showed that all compounds showed good antiproliferative activity. In particular, compound 2.1 showed the most prominent inhibition of VX2 cell lines with IC₅₀ of 3.80 ± 0.75 μM. Compound 2.2 exhibited highly potent anticancer activity of stomach MGC cell lines with IC₅₀ of 3.72 ± 0.11 μM. A549 and MKN45 cell lines were sensitive to compound 2.5 with IC₅₀ of 5.47 ± 1.11 and 3.04 ± 0.02 μM, respectively.     

Preorganization boosts the artificial esterase activity of a self-assembling peptide

The creation of artificial enzymes to mimic natural enzymes remains a great challenge owing to the complexity of the structural arrangement of the essential amino acids in catalytic centers. In this study, we used the phosphatase-based enzyme-instructed self-assembly(EISA) to supervise artificial esterases' final structures and catalytic activities. We reported that peptide precursors containing different phosphorylation sites could preorganize into alternated nanostructures and undergo dephosphorylation in the presence of alkaline phosphatase(ALP) with variation in kinetic and thermodynamic profiles. Although identical self-assembly compositions were formed after dephosphorylation, precursors with more enhanced preorganized states tended to better promote ALP dephosphorylation, facilitate further self-assembly, and strengthen the catalytic activities of the final assemblies. We envisioned that our strategy would be useful for further construction and manipulation of various artificial enzymes with superior catalytic activities.     

A strategy to enhance the thermal stability of a nanostructured polypyrrole-based coating for solid phase microextraction

We report on a nanostructured self-doped polypyrrole (SPPy) film that was prepared by an electrochemical technique in an electrolyte containing fluorosulfonic acid as the sulfonation reagent. The film was applied as a new fiber material for solid-phase microextraction (SPME) of the pesticides lindane, heptachlor, aldrin, endosulfans I and II prior to their quantitation by GC with electron capture detection. The SPPy nanoparticles have a diameter of <100?nm. The introduction of covalently bound sulfo groups into the backbone of the polymer resulted in improved temperature resistance (~350?°C) and satisfactory extraction efficiency. The thermal stability of the SPPy fiber is superior to common polypyrrole fibers. Extraction was optimized by means of the Taguchi orthogonal array experimental design with an OA₁₆ (4⁵) matrix including extraction temperature, extraction time, salt concentration, stirring rate, and headspace volume. The method displays good repeatability (RSD?<?6%) and linearity (in the range from 0.78 to 100?ng?mL^?1; with an R² of >0.998. The detection limits are <0.23?ng?mL^?1. The method was successfully applied to the analysis of the pesticides in skimmed milk and fruit juice samples, and recoveries are from 84?±?1 to 105?±?1%.

A collaborative CeO2@metal-organic framework nanosystem to endow scaffolds with photodynamic antibacterial effect

Antibacterial photodynamic therapy had attracted considerable attention in implant-associated infections treatment due to its high selectivity and no resistance. Actually, bacteria readily formed protective biofilm to cover themselves and impede the permeation of photosensitizers, severely impairing the therapeutic effect. Herein, a collaborative nanosystem was constructed by in-situ growing cerium oxide (CeO₂) nanoparticles on porphyrinic metal-organic framework PCN-224, and then mixed with poly-l-lactic acid (PLLA) powder to fabricate CeO₂@PCN-224/PLLA scaffold. In the nanosystem, CeO₂ was expected to disrupt the biofilm integrity by releasing Ce⁴⁺, exposing bacteria. Subsequently, PCN-224 could grab this opportunity to kill the bacteria by generating reactive oxygen species (ROS) under light irradiation, thereby achieving the desired antibacterial effect. Crystal violet staining and agarose gel electrophoresis results demonstrated that the bacterial biofilm was effectively eliminated by cleaving the extracellular DNA chains. Coomassie brilliant blue and acridine orange staining revealed that the generated ROS effectively killed bacteria by destroying their cell membrane, causing DNA hydrolysis and protein leakage. Furthermore, ROS could also weaken the antioxidant capacity of bacteria by consuming their glutathione, further accelerating bacterial death. As a consequence, the scaffolds presented a robust antibacterial rate of 97% against S. aureus. Collectively, this work provides a promising strategy for efficient implant-related infection treatment.     

Erratum to: Synthesis and anticancer activity of some new pyridine derivatives

Research on Chemical Intermediates -