Evaluation of [18F]fluoroestradiol and ChRERα as a gene expression PET reporter system in rhesus monkey brain.

Positron emission tomography (PET) reporter systems are a valuable means of estimating the level of expression of a transgene in vivo. For example, the safety and efficacy of gene therapy approaches for the treatment of neurological and neuropsychiatric disorders could be enhanced via the monitoring of exogenous gene expression levels in the brain. The present study evaluated the ability of a newly developed PET reporter system [18F]fluoroestradiol ([18F]FES) and the estrogen receptor-based PET reporter ChRERα, to monitor expression levels of a small hairpin RNA (shRNA) designed to suppress choline acetyltransferase (ChAT) expression in rhesus monkey brain. The ChRERα gene and shRNA were expressed from the same transcript via lentivirus injected into monkey striatum. In two monkeys that received injections of viral vector, [18F]FES binding increased by 70% and 86% at the target sites compared with pre-injection, demonstrating that ChRERα expression could be visualized in vivo with PET imaging. Post-mortem immunohistochemistry confirmed that ChAT expression was significantly suppressed in regions in which [18F]FES uptake was increased. The consistency between PET imaging and immunohistochemical results suggests that [18F]FES and ChRERα can serve as a PET reporter system in rhesus monkey brain for in vivo evaluation of the expression of potential therapeutic agents, such as shRNAs.

Design, synthesis and in vitro evaluation of novel thiazole-coumarin hybrids as selective and potent human carbonic anhydrase IX and XII inhibitors.

The coumarin is one of the most promising classes of non-classical carbonic anhydrase (CA, EC 4.2.1.1) inhibitors. In continuation of our ongoing work on search of coumarin based selective carbonic anhydrase inhibitors, a new series of 6-aminocoumarin based 16 novel analogues of coumarin incorporating thiazole (4a-p) have been synthesized and studied for their hCA inhibitory activity against a panel of human carbonic anhydrases (hCAs). Most of these newly synthesized compounds exhibited interesting inhibition constants in the nanomolar range. Among the tested compounds, the compounds 4f having 4-methoxy substitution exhibited activity at 90.9 nM against hCA XII isoform. It is noteworthy to see that all compounds were specifically and selectively active against isoforms hCA IX and hCA XII, with Ki under 1000 nM range. It is anticipated that these newly synthesized coumarin-thiazole hybrids (4a-p) may emerge as potential leads candidates against hCA IX and hCA XII as selective inhibitors compared to hCA I and hCA II.

Evaluation of phytoconstituents in marigold effluent for their antifungal activity against plant pathogens.

The current study placed an intense emphasis on the excess discharge of agro-based industrial effluent and the use of plant extract antimicrobials to inhibit the growth of pathogens in crop plants. An effluent (treated and untreated) from the marigold flower processing industry has been identified for the presence of volatile and semi-volatile organic compounds, and a total of 18 in treated effluent and 23 in untreated effluent were found using gas chromatography-mass spectrometry. A total of 13 classes were identified, which include carboxylic acid, phenols, esters, alkanes, alkenes, alcohols, cyanide, heterocyclic, flavonoids, aldehydes, polycyclic aromatic, cycloalkanes, and cycloalkenes. A principal component analysis with varimax rotation was applied to discern the abundance of identified compounds under each class. An in vitro antifungal bioassay was conducted using effluents at three different concentrations against plant pathogens (Alternaria alter nata, Sclerotium rolfsii, Rhizoctonia solani, Pythium aphanidermata, Fusarium oxysporum, and Colletotrichum gloeosporioides). The study proved that treated and untreated effluents clearly inhibited the growth of fungal pathogens by 10 to 32% and 37 to 92%, respectively. The findings suggest that marigold flower effluent can be a promising resource for developing new plant protection methods that are effective against pathogenic fungi.

Synthesis and preclinical evaluation of [11C]uPSEM792 for PSAM4-GlyR based chemogenetics.

Chemogenetic tools are designed to control neuronal signaling. These tools have the potential to contribute to the understanding of neuropsychiatric disorders and to the development of new treatments. One such chemogenetic technology comprises modified Pharmacologically Selective Actuator Modules (PSAMs) paired with Pharmacologically Selective Effector Molecules (PSEMs). PSAMs are receptors with ligand-binding domains that have been modified to interact only with a specific small-molecule agonist, designated a PSEM. PSAM4 is a triple mutant PSAM derived from the α7 nicotinic receptor (α7L131G,Q139L,Y217F). Although having no constitutive activity as a ligand-gated ion channel, PSAM4 has been coupled to the serotonin 5-HT3 receptor (5-HT3R) and to the glycine receptor (GlyR). Treatment with the partner PSEM to activate PSAM4-5-HT3 or PSAM4-GlyR, causes neuronal activation or silencing, respectively. A suitably designed radioligand may enable selective visualization of the expression and location of PSAMs with positron emission tomography (PET). Here, we evaluated uPSEM792, an ultrapotent PSEM for PSAM4-GlyR, as a possible lead for PET radioligand development. We labeled uPSEM792 with the positron-emitter, carbon-11 (t1/2 = 20.4 min), in high radiochemical yield by treating a protected precursor with [11C]iodomethane followed by base deprotection. PET experiments with [11C]uPSEM792 in rodents and in a monkey transduced with PSAM4-GlyR showed low peak radioactivity uptake in brain. This low uptake was probably due to high polarity of the radioligand, as evidenced by physicochemical measurements, and to the vulnerability of the radioligand to efflux transport at the blood-brain barrier. These findings can inform the design of a more effective PSAM4 based PET radioligand, based on the uPSEM792 chemotype.

PET reporter systems for the brain.

Positron emission tomography (PET) can be used as a noninvasive method to longitudinally monitor and quantify the expression of proteins in the brain in vivo. It can be used to monitor changes in biomarkers of mental health disorders, and to assess therapeutic interventions such as stem cell and molecular genetic therapies. The utility of PET monitoring depends on the availability of a radiotracer with good central nervous system (CNS) penetration and high selectivity for the target protein. This review evaluates existing methods for the visualization of reporter proteins and/or protein function using PET imaging, focusing on engineered systems, and discusses possible approaches for future success in the development of high-sensitivity and high-specificity PET reporter systems for the brain.

PET radiotracers and fluorescent probes for imaging human carbonic anhydrase IX and XII in hypoxic tumors.

Positron emission tomography (PET) and fluorescent imaging play a pivotal role in medical diagnosis, biomedical oncologic research, and drug development process, which include identification of target location, target engagement, but also prove on mechanism of action or pharmacokinetics of new drug candidates. PET estimates physiological changes at the molecular level using specific radiotracers containing a short-lived positron emitting radionuclide such as fluorine-18 or carbon-11, whereas fluorescent imaging techniques use fluorescent probes labeled with suitable drug candidates for detection at the molecular level. The human carbonic anhydrase (hCA) isoforms IX and XII are overexpressed in hypoxic cancer cells, promoting tumor growth by regulating extra/intracellular pH, ferroptosis, and metabolism, being recognized as promising targets for anticancer theranostic agents. In this review, we have focused on PET radiotracers as well as fluorescent probes for diagnosis and treatment of tumors expressing hCA IX and hCA XII.

Anticancer carbonic anhydrase inhibitors: a patent and literature update 2018-2022.

INTRODUCTION: Cancer affects an increasing number of patients each year with an unacceptable death toll worldwide. A new therapeutic approach to combat tumors consists in targeting human carbonic anhydrase (hCA, EC 4.2.1.1) isoforms IX and XII, which are tumor-associated, overexpressed enzymes in hypoxic tumors, being involved in metabolism, pH regulation, ferroptosis, and overall tumor progression. AREAS COVERED: Small molecule hCA IX/XII and antibody drug conjugate inhibitors targeting the two enzymes and their applications in the management of cancer are discussed. EXPERT OPINION: The available 3D crystal structures of hCA IX, XII as well as the off target isoforms hCA I and II, afforded structure-based drug design opportunities, which led to the development of various isoform-selective small molecule inhibitors belonging to diverse classes (sulfonamides, sulfamates, benzoxaboroles, selenols, coumarins, sulfocoumarins, and isocoumarins). Many patents focused on small inhibitors containing sulfonamide/sulfamide/sulfamide derivatives as well as hybrids incorporating sulfonamides and different antitumor chemotypes, such as cytotoxic drugs, kinase/telomerase inhibitors, P-gp and thioredoxin inhibitors. The most investigated candidate belonging to the class is the sulfonamide SLC-0111, in Phase Ib/II clinical trials for the management of advanced, metastatic solid tumors.

Carbon-11 patents (2012-2022): synthetic methodologies and novel radiotracers for PET imaging.

INTRODUCTION: Carbon-11 is a short-lived radionuclide with versatile applications in synthetic methodologies to develop a variety of novel PET radiotracers. Different primary and secondary carbon-11 precursors are generated from cyclotron produced [11C]CO2 and used to insert carbon-11 radionuclide into the target-specific bioactive molecules. AREAS COVERED: In this review, the patents as well as specific research articles on carbon-11 radiotracer synthesis and PET imaging applications in various diseases are mentioned since 2012 to 2022 through SciFinder database. EXPERT OPINION: Carbon-11 is generally easier to insert into more organic scaffolds as a greater variety of functional groups. Despite the short half-life of carbon-11 radionuclide (t1/2 = 20.4 min), it is widely used in PET radiotracer development due to its direct insertion into bioactive compounds and less isotopic dilution unlike other positron emitters like fluorine-18. Various synthons can be easily generated using the primary and secondary carbon-11 precursors . The carbon-11 radiotracers provide target-oriented information associated with the pharmacology, and physiological conditions of the disease status. Various protocols and automated methods were adapted for easy and convenient synthesis of carbon-11 radiotracers. The PET advances drug development and clinical trials by revealing biological target engagement, proof of mechanism, pharmacokinetic, and pharmacodynamic profiles of new drug candidates using selective radiotracers.

PET Molecular Imaging in Drug Development: The Imaging and Chemistry Perspective.

Positron emission tomography with selective radioligands advances the drug discovery and development process by revealing information about target engagement, proof of mechanism, pharmacokinetic and pharmacodynamic profiles. Positron emission tomography (PET) is an essential and highly significant tool to study therapeutic drug development, dose regimen, and the drug plasma concentrations of new drug candidates. Selective radioligands bring up target-specific information in several disease states including cancer, cardiovascular, and neurological conditions by quantifying various rates of biological processes with PET, which are associated with its physiological changes in living subjects, thus it reveals disease progression and also advances the clinical investigation. This study explores the major roles, applications, and advances of PET molecular imaging in drug discovery and development process with a wide range of radiochemistry as well as clinical outcomes of positron-emitting carbon-11 and fluorine-18 radiotracers.

Synthetic methodologies and PET imaging applications of fluorine-18 radiotracers: a patent review.

INTRODUCTION: Fluorine-18 is a promising radionuclide for developing novel PET radiotracers due to its characteristic features such as convenient half-life, metabolic stability, good imaging properties, and easy access to various clinical PET centers. Currently, many 18F-radiotracers are available to study disease status in the fields of oncology, cardiology, and neurology. AREAS COVERED: In this review, the authors have covered patents and research papers of 18F-radiotracers with clinical applications in various diseases using PET modality since 2015 until the present through SciFinder database. EXPERT OPINION: Despite other PET radionuclides 11C, 13N, and 15O, the 18F is widely used for radiotracer development because of maximum half-life of 109.8 min. The major limitations of PET radiotracer development include low radiochemical yields and less regioselectivity of the radiofluorination reactions. Therefore, various synthetic methodologies were developed for radiofluorination via nucleophilic, electrophilic with specific precursors, transition metal mediated, and prosthetic groups mediated radiofluorination. Automated radiosynthesis methods have been adapted for easy and convenient synthesis of various 18F-radiotracers, whereas the PET provides functional information about a disease condition through its pharmacology and physiological processes in vivo, and it is also an essential tool in drug discovery to study therapeutic drug development, and pharmacokinetic profiles.

Novel trisaccharide based phospholipids as immunomodulators.

A focused library of novel mannosylated glycophospholipids was synthesized employing imidate coupling and H-phosphate phosphorylation methods. All novel glycophospholipids were evaluated for their receptor interactions by molecular docking studies. Docking studies revealed dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN) specific interaction of the glycophospholipid ligand P4 acts, which was further confirmed by in vitro DC-SIGN expression on monocyte-derived dendritic cells (MoDCs). Further, in vitro and in vivo immunomodulatory activity among the six compounds (P1-P6) examined, compound P4 displayed good immunopotentiation and adjuvant properties as indicated by the induced cytokine expression and enhanced ovalbumin (OVA) specific antibody (IgG) titers. Phosphatidylinositol mannosides (PIMs) analogues in the present study enforced the immunomodulatory properties, truncating parent PIMs or tailor-made of PIMs may bring the novel efficacious molecules, which will be useful in vaccine preparation against different diseases.