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Topic Review
Radiolabeled Peptoids and Peptoid/Peptide Hybrids for Cancer-Targeted Imaging
Peptoids (N-substituted glycine oligomers) are a relatively new class of peptidomimetics, being highly versatile and capable of mimicking the architectures and the activities of the peptides but with a marked resistance to proteases and a propensity to cross the cellular membranes over the peptides themselves. For these properties, they have gained an ever greater interest in applications in bioengineering and biomedical fields.
  • 564
  • 30 Nov 2023
Topic Review
The Mammalian Thioredoxin Reductase Probes
The cardinal component of the thioredoxin system, mammalian thioredoxin reductase (TrxR) plays a vital role in supporting various physiological functions; however, its malfunction, disrupting redox balance, is intimately associated with the pathogenesis of multiple diseases. Fluorescent probes offer several advantages for in situ imaging and the quantification of biological targets, such as non-destructiveness, real-time analysis, and high spatiotemporal resolution. These benefits facilitate the transition from a poise to a flux understanding of cellular targets, further advancing scientific studies in related fields. The TrxR fluorescent probes have contributed significantly to the investigation of TrxR’s biological functions and have been valuable tools in TrxR-related research.
  • 544
  • 24 Aug 2023
Topic Review
Modeling for CADD with Small Molecules
COVID-19 has claimed around 7 million lives (from December 2019–November 2023) worldwide and continues to impact global health. SARS-CoV-2, the virus causing COVID-19 disease, is characterized by a high rate of mutations, which contributes to its rapid spread, virulence, and vaccine escape. While several vaccines have been produced to minimize the severity of the coronavirus, and diverse treatment regimens have been approved by the US FDA under Emergency Use Authorization (EUA), SARS-CoV-2 viral mutations continue to derail the efforts of scientists as the emerging variants evade the recommended therapies. Nonetheless, diverse computational models exist that offer an opportunity for the swift development of new drugs or the repurposing of old drugs. 
  • 519
  • 10 Jan 2024
Topic Review Peer Reviewed
Challenges and Recommendations on Digital Health Sources in Pediatric Chronic Suppurative Lung Diseases
In the context of digitalizing healthcare systems, digital health sources (DHSs) aim to enhance the efficiency, accessibility, and quality of healthcare services by leveraging technology. Multiple types of DHSs are increasingly established in healthcare, providing direct and wide communication between pediatric patients, parents, and healthcare professionals. Therefore, they are considered promising key tools to improve pediatric disease monitoring and management. At the same time, DHSs have been associated with several issues and risks, such as those related to data sharing, privacy, and the cultural readiness of the users. Yet, discussions in the literature have mostly focused on technical considerations and a user-friendly design. In contrast, the contribution of DHSs to treatment engagement in pediatric populations and data sharing has only partially been discussed. On this basis, we provide an overview of the available digital health technologies and their application in the pediatric population with chronic suppurative lung diseases; we describe the effectiveness in health-related outcomes, discuss possible challenges, and propose some recommendations that may overcome barriers in their everyday use.
  • 353
  • 06 Jan 2025
Topic Review
Phytochemistry
Phytochemistry is the branch of plant science concerned with the chemical constituents of plants, their occurrence, distribution, structural characteristics, biosynthesis, accumulation, transformation, and biological activities [1][2]. Its subject matter includes primary metabolites required for plant growth and cellular function, as well as specialized metabolites—often termed secondary metabolites—such as alkaloids, terpenoids, phenolic compounds, and flavonoids [3][4]. Phytochemical investigation commonly involves the preparation and extraction of plant material, chromatographic separation, spectroscopic or spectrometric characterization, quantitative analysis, and evaluation of biological activity. The field addresses chemical variation among plant taxa, tissues, developmental stages, environmental conditions, and geographic populations, together with the metabolic pathways responsible for the formation and modification of plant constituents [2][5]. Within the taxonomy of phytochemistry and biological activities, the term includes the integrated study of plant-derived molecules and the biological properties associated with those molecules, including their ecological, physiological, pharmacological, toxicological, and antimicrobial activities [1][4].
  • 18
  • 26 Oct 2026
Topic Review
Alkaloids
Alkaloids constitute a class of nitrogen-containing specialised metabolites that are biosynthesised by plants, fungi, bacteria, and certain animals and are characterised by the presence of at least one nitrogen atom within their molecular framework [1][2]. This nitrogen atom is typically basic and, in the majority of alkaloids, is incorporated into a heterocyclic ring system, a structural feature that confers the alkaline character from which the class derives its name [3][4]. Alkaloids are further organised according to their biosynthetic origin into three structural categories: true alkaloids, in which the nitrogen atom is derived from an amino acid and resides within a heterocycle; proto-alkaloids, in which the nitrogen is amino-acid-derived but lies outside a heterocyclic ring; and pseudo-alkaloids, in which the nitrogen is introduced at a late biosynthetic stage and is not amino-acid-derived [3][5]. The class is defined by pronounced structural diversity, with more than 27,000 structures reported and approximately 21,000 of these isolated from plants, and by a correspondingly broad range of biological activities that include toxicity, antimicrobial action, and pharmacological activity in humans and other animals [1][2]. Within the taxonomy of alkaloid synthesis and bioactivity, the term designates this nitrogen-containing, structurally heterogeneous group of specialised metabolites together with the biosynthetic pathways—rooted in amino acid metabolism and centred on iminium cation chemistry—through which their characteristic nitrogen heterocyclic scaffolds are constructed [1][3].
  • 16
  • 26 Oct 2026
Topic Review
Bioisosteric Drug Design
Bioisosteric drug design is the replacement of an atom, functional group, or molecular fragment with another moiety selected to reproduce relevant steric, electronic, or interaction properties in a bioactive molecule. The replacement preserves selected features of molecular recognition while changing properties such as ionization, polarity, conformational preference, or susceptibility to metabolism. Bioisosteric relationships extend beyond atoms of similar valence and include replacements with substantially different chemical connectivity [1]. Saturated carbon frameworks can reproduce the spatial arrangement of substituents on an aromatic ring while changing three-dimensional shape and physicochemical behaviour [2]. For example, appropriately substituted bicyclo[3.1.1]heptanes can approximate the substituent vectors of meta-substituted benzene rings [3]. Functional group replacements can also preserve hydrogen bonding patterns; squaramides offer geometries and donor–acceptor features relevant to several amide-related groups [4]. Equivalence is therefore specific to the molecular setting and the property being preserved, rather than an assertion that two fragments have identical biological effects [1][2].
  • 13
  • 25 Oct 2026
Topic Review
Natural Product Chemistry
Natural product chemistry is the interdisciplinary branch of chemical and biological science concerned with the study of naturally occurring chemical compounds produced by living organisms. Within the context of bioactive natural compounds, it encompasses the isolation of metabolites from biological sources; determination of their molecular structures, stereochemistry, and chemical properties; investigation of their biosynthetic origins; and characterization of their chemical and biological relationships [1][2]. Its principal subject matter includes specialized metabolites—also termed secondary metabolites—whose structures are assembled from primary metabolic precursors through biosynthetic pathways. Major natural-product classes include alkaloids, terpenoids, polyketides, non-ribosomal peptides, ribosomally synthesized and post-translationally modified peptides, and structurally modified lipids [2][3]. Natural product chemistry is distinguished from synthetic organic chemistry by its focus on compounds of biological origin and from natural-product biosynthesis by its broader inclusion of isolation, structural elucidation, chemical characterization, and structure–activity analysis. Although chemical synthesis, spectroscopy, chromatography, genomics, and enzymology may be used within the discipline, these are methodological components rather than the defining subject of the field [1][2][3].
  • 12
  • 24 Oct 2026
Topic Review
Calpain Inhibitor
A calpain inhibitor is a molecule that reduces the proteolytic activity of one or more members of the calpain family, particularly the calcium-activated cysteine proteases calpain-1 and calpain-2 [1]. Calpains cleave selected peptide bonds within cellular proteins, and their inhibition limits this processing rather than directly preventing protein synthesis [1][2]. Inhibitors include synthetic small molecules, peptide derivatives, and the endogenous regulatory protein calpastatin. Many small-molecule inhibitors interact with the catalytic cleft, where electrophilic groups can engage the active-site cysteine; individual compounds differ in reversibility and activity against other cysteine proteases [2]. Calpastatin uses a distinct recognition mechanism involving several contacts with calcium-activated calpain. Its inhibitory segment occupies the substrate-binding cleft while a loop passes around the catalytic cysteine, avoiding cleavage of the inhibitor itself [3][4]. Each of its four inhibitory repeats can engage a calpain molecule [4]. Inhibition therefore encompasses chemically diverse interactions that suppress substrate cleavage, with specificity varying among compounds and calpain isoforms [1][2].
  • 4
  • 05 Nov 2026
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