Synthesis, radiolabelling and initial biological characterisation of 18F-labelled xanthine derivatives for PET imaging of Eph receptors

Immunohistochemical expression of ephrin receptors in neuroendocrine neoplasms: a case-series of gastroenteropancreatic neuroendocrine neoplasms and a systematic review of the literature

PURPOSE

Erythropoietin-producing hepatocellular (EPH) receptors are the largest known family of tyrosine kinases receptors (TKR) in humans, implicated in cell proliferation, adhesion, migration, tumor angiogenesis, invasion and metastasis. The aim of the present study is to assess the expression of EPHs in neuroendocrine neoplasms (NENs).

METHODS

Immunohistochemical staining of specimens of 30 patients with gastroenteropancreatic and lung NENs was performed for EPH-A1, EPH-A2, EPH-A4, EPH-A5 protein expression, in addition to ki-67 multiplication index and programmed death-ligand 1. Additionally, we performed a systematic review of the available literature in three different databases reporting on the expression of EPH in all neuroendocrine neoplasms.

RESULTS

Positive expression was seen in 16/19 (84%) specimens for EPH-A1, 15/23 (65%) for EPH-A2, 21/24 (88%) for EPH-A4, 24/26 (92%) for EPH-A5. EPH-A1 was expressed in 9/9 pancreatic, 3/4 small intestine, but not in one lung NEN, EPH-A2 in 5/10 pancreatic, 3/4 small intestine and lung, and in one of each of gastric, appendix, colorectal, and cervical NENs, respectively. EPH-A4 showed positive expression in 9/11 pancreatic, 4/4 small intestine, 3/3 lung specimens and EPH-A5 in 10/11, 4/4 and 4/4, respectively. Data retrieved from the systematic review of the literature in combination with the data from the present study are suggestive of a frequent EPH expression in pituitary, thyroid, lung and gastroenteropancreatic NENs, yet, with varying expressions of the single receptor subtypes.

CONCLUSION

EPHs may have a role in NEN tumorigenesis, prognosis as well as a role in the evolving molecular-targeted therapies.

A Comprehensive Review: Versatile Imaging Probe Based on Chemical Materials for Biomedical Applications

Imaging probe and contrast agents play significant role in combating cancer. Based on special chemical materials, imaging probe can convert cancer symptoms into information-rich images with high sensitivity and signal amplification, accompanying with detection, diagnosis, drug delivery and treatment. In the paper, some inorganic and organic chemical materials as imaging probe, including Ultrasound imaging (US), Optical imaging (OP), Photoacoustic imaging (PA), X-ray Computed Tomography (CT), Magnetic Resonance imaging (MRI), Radionuclide imaging (RNI) probe, as well as multi-modality imaging probe for diagnosis and therapy of tumour were introduced. The sophisticated and comprehensive chemical materials as imaging probe were highlighted in detail. Meanwhile, the advantages and disadvantages of the imaging probe were compared. In order to provide some reference and help researchers for construction imaging probe for tumour diagnosis and treatment, it attempts to exhaustively cover the whole field. Finally, the prospect and challenge for imaging probe were discussed.

Recent advances in the synthesis, reaction, and bio-evaluation potential of purines as precursor pharmacophores in chemical reactions: a review

Purines are nitrogenous heterocyclic compounds characterized by the presence of two fused rings: pyrimidine and imidazole. Their significance is underscored by their widespread occurrence in natural products as the metabolic processes of all living organisms heavily rely on purines and their synthetic derivatives. Furthermore, purines exhibit considerable bioactivity, highlighting their importance in biological systems. Given their unique structural characteristics and ability to yield a diverse array of bioactive molecules, purines have attracted substantial attention from researchers. This review illustrates the recent methods for the synthesis of purines from diaminomaleonitrile, urea derivatives, imidazole, and pyrimidine derivatives reported from 2019 to 2024. Additionally, it elucidates the various chemical modifications applied to the purine nucleus, including benzoylation, alkylation, halogenation, amination, selenylation, thiolation, condensation, diazotization, coupling reactions, and other miscellaneous reactions. Moreover, this review discusses several biological evaluations, including the mechanisms of action of purine derivatives as anticancer, antimicrobial, anti-inflammatory, antiviral, antioxidant, and anti-Alzheimer agents. This review aims to assist researchers in synthetic organic and medicinal chemistry toward the development and enhancement of novel methodologies for the synthesis of new purine molecules while supporting biologists in the identification of new targets for bio-evaluation.

Discovery of a new 1-(phenylsulfonyl)-1H-indole derivative targeting the EphA2 receptor with antiproliferative activity on U251 glioblastoma cell line

In our continuing effort devoted at developing agents targeting the EphA2 receptor by means of protein-protein interaction (PPI) inhibitors, we report here the design and synthesis of a new class of l-β-homotryptophan conjugates of 3-β-hydroxy-Δ5-cholenic acid bearing a set of arylsulfonyl substituents at the indole nitrogen atom. An extensive structure-activity relationship (SAR) analysis indicates that the presence of a bulky lipophilic moiety at the indole nitrogen is fundamental for improving potency on the EphA2 receptor, while abrogating activity on the EphB1-EphB3 receptor subtypes. A rational exploration, guided by the combined application of an experimental design on σp and π physicochemical descriptors and docking simulations, led to the discovery of UniPR1454, a 1-(4-(trifluoromethyl)phenyl)sulfonyl derivative acting as potent and competitive EphA2 antagonist able to inhibit ephrin-A1 dependent signals and to reduce proliferation of glioblastoma (U251) cell line at micromolar concentration.

Molecular Insights on Coffee Components as Chemical Antioxidants

Coffee is not only a delicious beverage but also an important dietary source of natural antioxidants. We live in a world where it is impossible to avoid pollution, stress, food additives, radiation, and other sources of oxidants that eventually lead to severe health disorders. Fortunately, there are chemicals in our diet that counteract the hazards posed by the reactive species that trigger oxidative stress. They are usually referred to as antioxidants; some of them can be versatile compounds that exert such a role in many ways. This review summarizes, from a chemical point of view, the antioxidant effects of relevant molecules found in coffee. Their mechanisms of action, trends in activity, and the influence of media and pH in aqueous solutions, are analyzed. Structure-activity relationships are discussed, and the protective roles of these compounds are examined. A particular section is devoted to derivatives of some coffee components, and another one to their bioactivity. The data used in the analysis come from theoretical and computational protocols, which have been proven to be very useful in this context. Hopefully, the information provided here will pro-mote further investigations into the amazing chemistry contained in our morning coffee cup.   Resumen. El café no solo es una bebida deliciosa, sino también una importante fuente dietética de antioxidantes naturales. Vivimos en un mundo donde es imposible evitar la contaminación, el estrés, los aditivos alimentarios, la radiación y otras fuentes de oxidantes que eventualmente conducen a trastornos de salud graves. Afortunadamente, existen sustancias químicas en nuestra dieta que contrarrestan los peligros planteados por las especies reactivas que desencadenan el estrés oxidativo. Por lo general, se les denomina antioxidantes; algunos de ellos pueden ser compuestos versátiles que ejercen dicho papel de muchas maneras. Este artículo de revisión resume, desde un punto de vista químico, los efectos antioxidantes de moléculas relevantes encontradas en el café. Se analizan sus mecanismos de acción, tendencias en la actividad y la influencia del medio y el pH en soluciones acuosas. Se discuten las relaciones estructura-actividad, y se examinan los roles protectores de estos compuestos. Se dedica una sección particular a los derivados de algunos componentes del café, y otra a su bioactividad. Los datos utilizados en el análisis provienen de protocolos teóricos y computacionales, que han demostrado ser muy útiles en este contexto. Se espera que la información proporcionada aquí promueva investigaciones futuras sobre la química contenida en nuestra taza de café matutina.

Novel Receptor Tyrosine Kinase Pathway Inhibitors for Targeted Radionuclide Therapy of Glioblastoma

Glioblastoma (GB) remains the most fatal brain tumor characterized by a high infiltration rate and treatment resistance. Overexpression and/or mutation of receptor tyrosine kinases is common in GB, which subsequently leads to the activation of many downstream pathways that have a critical impact on tumor progression and therapy resistance. Therefore, receptor tyrosine kinase inhibitors (RTKIs) have been investigated to improve the dismal prognosis of GB in an effort to evolve into a personalized targeted therapy strategy with a better treatment outcome. Numerous RTKIs have been approved in the clinic and several radiopharmaceuticals are part of (pre)clinical trials as a non-invasive method to identify patients who could benefit from RTKI. The latter opens up the scope for theranostic applications. In this review, the present status of RTKIs for the treatment, nuclear imaging and targeted radionuclide therapy of GB is presented. The focus will be on seven tyrosine kinase receptors, based on their central role in GB: EGFR, VEGFR, MET, PDGFR, FGFR, Eph receptor and IGF1R. Finally, by way of analyzing structural and physiological characteristics of the TKIs with promising clinical trial results, four small molecule RTKIs were selected based on their potential to become new therapeutic GB radiopharmaceuticals.

A comprehensive survey upon diverse and prolific applications of chitosan-based catalytic systems in one-pot multi-component synthesis of heterocyclic rings

Heterocyclic compounds are among the most prestigious and valuable chemical molecules with diverse and magnificent applications in various sciences. Due to the remarkable and numerous properties of the heterocyclic frameworks, the development of efficient and convenient synthetic methods for the preparation of such outstanding compounds is of great importance. Undoubtedly, catalysis has a conspicuous role in modern chemical synthesis and green chemistry. Therefore, when designing a chemical reaction, choosing and or preparing powerful and environmentally benign simple catalysts or complicated catalytic systems for an acceleration of the chemical reaction is a pivotal part of work for synthetic chemists. Chitosan, as a biocompatible and biodegradable pseudo-natural polysaccharide is one of the excellent choices for the preparation of suitable catalytic systems due to its unique properties. In this review paper, every effort has been made to cover all research articles in the field of one-pot synthesis of heterocyclic frameworks in the presence of chitosan-based catalytic systems, which were published roughly by the first quarter of 2020. It is hoped that this review paper can be a little help to synthetic scientists, methodologists, and catalyst designers, both on the laboratory and industrial scales.

Evaluation of EphB4 as Target for Image-Guided Surgery of Breast Cancer

Background: Targeted image-guided surgery is based on the detection of tumor cells after administration of a radio-active or fluorescent tracer. Hence, enhanced binding of a tracer to tumor tissue compared to healthy tissue is crucial. Various tumor antigens have been evaluated as possible targets for image-guided surgery of breast cancer, with mixed results. Methods: In this study we have evaluated tyrosine kinase receptor EphB4, a member from the Eph tyrosine kinase receptor family, as a possible target for image-guided surgery of breast cancers. Two independent tissue micro arrays, consisting of matched sets of tumor and normal breast tissue, were stained for EphB4 by immunohistochemistry. The intensity of staining and the percentage of stained cells were scored by two independent investigators. Results: Immunohistochemical staining for EphB4 shows that breast cancer cells display enhanced membranous expression compared to adjacent normal breast tissue. The enhanced tumor staining is not associated with clinical variables like age of the patient or stage or subtype of the tumor, including Her2-status. Conclusion: These data suggest that EphB4 is a promising candidate for targeted image-guided surgery of breast cancer, especially for Her2 negative cases.

Radiopharmacologist's and Radiochemist's View on Targeting the Eph/Ephrin Receptor Tyrosine Kinase System

In the past decade, there have been extensive efforts to open up the Eph/ephrin subfamily of the receptor tyrosine kinase family for diagnostic and therapeutic applications. Besides classical pharmaceutical developments, which focus either on drugs targeting the extracellular ligand binding domains or on the intracellular tyrosine kinase domains of these receptors, there also have been first radiopharmaceutical approaches. Here the focus is on the development of specific and selective probes for molecular imaging, particularly by means of positron emission tomography, and the functional characterization of the Eph/ephrin subfamily in certain target tissues. The aim of this mini-review is to summarize the different approaches toward Eph-targeting radiotracers by using antibodies, peptides, and small molecules and to discuss their radiopharmacological characterization. With regard to the small molecules, further considerations will focus on the design and synthesis of nonradioactive reference compounds and precursors as well as on radiolabeling strategies.

Hot off the Press

A personal selection of 32 recent papers is presented covering various aspects of current developments in bioorganic chemistry and novel natural products such as sporormielone A from a Sporormiella species.