Advances in the Synthesis and Application of Heterocyclic Compounds

A special issue of Pharmaceuticals (ISSN 1424-8247). This special issue belongs to the section "Medicinal Chemistry".

Deadline for manuscript submissions: 31 December 2025 | Viewed by 3409

Special Issue Editors


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Guest Editor
Department of Chemical Organic Technology and Petrochemistry, The Silesian University of Technology, Krzywoustego 4, PL-44100 Gliwice, Poland
Interests: heterocyclic compounds; cross-coupling reaction; organic synthesis; azo compounds

E-Mail Website
Guest Editor
Department of Chemical Organic Technology and Petrochemistry, The Silesian University of Technology, Krzywoustego 4, PL-44100 Gliwice, Poland
Interests: heterocyclic compounds; synthesis; physical chemistry

Special Issue Information

Dear Colleagues,

The world is persistently moving forward and science is constantly developing; as a result, the knowledge of new generations is becoming enriched with new information. The world of science is filled with people who passionately explore chemistry, which we can compare to the discovery of the world by children playing with Lego blocks. Scientists are competing with each other to create new methods for the synthesis of compounds with valuable properties, for modifications of existing systems to improve their assets, or for the construction of entirely new structures in the hope of finding breakthrough activities. What once seemed impossible is now within reach.It is safe to say that when a chemical compound exhibits valuable biological properties, medicine becomes the leading area of scientists’ ​​interest. In pharmacology, heterocyclic compounds undoubtedly play a crucial role. Determining useful pharmacophores allows scientists to modify the structure of existing drugs or search for alternative solutions for specific biological targets.

This Special Issue of Pharmaceuticals aims to summarize information from original articles and reviews on new synthesis methods and applications of heterocyclic compounds in medicine.

Dr. Monika Olesiejuk
Prof. Dr. Agnieszka Kudelko
Guest Editors

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Keywords

  • organic synthesis
  • heterocyclic compounds
  • biological activity
  • medicine
  • therapeutics

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Published Papers (3 papers)

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Research

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50 pages, 5968 KB  
Article
Structure–Activity Relationship Study of 3-Alkynyl-6-aryl-isothiazolo[4,3-b]pyridines as Dual Inhibitors of the Lipid Kinases PIKfyve and PIP4K2C
by Demian Kalebic, Ling-Jie Gao, Belén Martinez-Gualda, Marwah Karim, Sirle Saul, Do Hoang Nhu Tran, Jef Rozenski, Leentje Persoons, Dominique Schols, Wim Dehaen, Shirit Einav and Steven De Jonghe
Pharmaceuticals 2025, 18(9), 1341; https://doi.org/10.3390/ph18091341 - 6 Sep 2025
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Abstract
Background/Objectives: RMC-113, a 3-alkynyl-6-aryl-disubstituted isothiazolo[4,3-b]pyridine, is a dual inhibitor of the lipid kinases PIKfyve and PIP4K2C with broad-spectrum antiviral activity. The aim was to study the structure–activity relationship (SAR) of isothiazolo[4,3-b]pyridines as dual PIKfyve/PIP4K2C inhibitors. Methods: A [...] Read more.
Background/Objectives: RMC-113, a 3-alkynyl-6-aryl-disubstituted isothiazolo[4,3-b]pyridine, is a dual inhibitor of the lipid kinases PIKfyve and PIP4K2C with broad-spectrum antiviral activity. The aim was to study the structure–activity relationship (SAR) of isothiazolo[4,3-b]pyridines as dual PIKfyve/PIP4K2C inhibitors. Methods: A series of isothiazolo[4,3-b]pyridines was synthesized by introducing structural variety at positions 3 and 6 of the central scaffold. The primary assay to guide the synthetic chemistry was a biochemical PIKfyve assay, with a number of analogues also tested for PIP4K2C binding affinity. Finally, isothiazolo[4,3-b]pyridines were also evaluated for antiviral and antitumoral activity in cell-based assays. Results: PIKfyve inhibition tolerated a wide variety of substituents on the aryl ring at position 6 of the isothiazolo[4,3-b]pyridine scaffold, with the 4-carboxamide analogue emerging as the most potent (IC50 = 1 nM). The SAR at position 3 was more restricted, although the introduction of electron-donating groups (such as a methyl and methoxy) on the pyridinyl ring yielded potent PIKfyve inhibitors, with IC50 values in the low nM range. The acetylenic moiety was essential for PIKfyve inhibition, and only the saturated ethyl linker displayed potent PIKfyve inhibition, albeit less active than the acetylene counterpart. The compounds were 2- to 5-fold less potent on PIP4K2C relative to PIKfyve. These dual PIKfyve/PIP4K2C inhibitors displayed antiviral activity against both the venezuelan equine encephalitis virus (VEEV) and the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). A screening against a panel of cancer cell lines revealed antitumoral activity, although some of the potent PIKfyve/PIP5K2C inhibitors lacked antitumoral activity. Conclusions: Isothiazolo[4,3-b]pyridines are dual PIKfyve/PIP4K2C inhibitors displaying broad-spectrum antiviral, as well as antitumoral, activity. Full article
(This article belongs to the Special Issue Advances in the Synthesis and Application of Heterocyclic Compounds)
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Review

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74 pages, 8029 KB  
Review
Antimicrobial Activity of 1,3,4-Thiadiazole Derivatives
by Sebastian Górecki, Agnieszka Kudelko and Monika Olesiejuk
Pharmaceuticals 2025, 18(9), 1348; https://doi.org/10.3390/ph18091348 - 8 Sep 2025
Abstract
The 1,3,4-thiadiazole core has attracted significant attention due to its unique electronic structure, physicochemical properties, and wide-ranging pharmacological potential. This heterocyclic scaffold exhibits a broad spectrum of biological activities, often attributed to its capacity to modulate enzyme function, interact with receptors, and disrupt [...] Read more.
The 1,3,4-thiadiazole core has attracted significant attention due to its unique electronic structure, physicochemical properties, and wide-ranging pharmacological potential. This heterocyclic scaffold exhibits a broad spectrum of biological activities, often attributed to its capacity to modulate enzyme function, interact with receptors, and disrupt key biochemical pathways in both pathogens and host cells. Additionally, 1,3,4-thiadiazoles typically display favorable pharmacokinetic properties, including high metabolic stability and appropriate lipophilicity, which enhance their drug-likeness and bioavailability. This review presents an overview of antibacterial and antifungal compounds bearing the 1,3,4-thiadiazole scaffold that have been reported over the past five years. This publication details the chemical structures of novel 1,3,4-thiadiazole derivatives and reports the results of antibacterial and antifungal activity assays conducted against a range of microbial strains. Furthermore, it provides conclusions regarding the structural features that influence the observed biological activity of the synthesized compounds. Antimicrobial activity assessments conducted against ten Gram-negative and nine Gram-positive bacterial strains revealed that 79 newly synthesized 1,3,4-thiadiazole derivatives exhibited either superior inhibitory efficacy relative to standard reference antibiotics or achieved a high level of bacterial growth suppression, defined as 90–100% inhibition. In antifungal assays, the compounds were evaluated against 25 fungal species representing 15 genera. Among the tested derivatives, 75 compounds demonstrated antifungal potency exceeding that of reference antifungal agents or produced growth inhibition within the 90–100% range. The information provided herein may serve as a valuable resource for medicinal and agricultural chemists engaged in the development of novel drug candidates and plant protection agents. Full article
(This article belongs to the Special Issue Advances in the Synthesis and Application of Heterocyclic Compounds)
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23 pages, 8189 KB  
Review
Exploring Macrocyclic Chemical Space: Strategies and Technologies for Drug Discovery
by Taegwan Kim, Eunbee Baek and Jonghoon Kim
Pharmaceuticals 2025, 18(5), 617; https://doi.org/10.3390/ph18050617 - 24 Apr 2025
Cited by 1 | Viewed by 2877
Abstract
Macrocycles have emerged as significant therapeutic candidates in drug discovery due to their unique capacity to target complex and traditionally inaccessible biological interfaces. Their structurally constrained three-dimensional configurations facilitate high-affinity interactions with challenging targets, notably protein–protein interfaces. However, despite their potential, the synthesis [...] Read more.
Macrocycles have emerged as significant therapeutic candidates in drug discovery due to their unique capacity to target complex and traditionally inaccessible biological interfaces. Their structurally constrained three-dimensional configurations facilitate high-affinity interactions with challenging targets, notably protein–protein interfaces. However, despite their potential, the synthesis and optimization of macrocyclic compounds present considerable challenges related to structural complexity, synthetic accessibility, and the attainment of favorable drug-like properties, particularly cell permeability and oral bioavailability. Recent advancements in synthetic methodologies have expanded the chemical space accessible to macrocycles, enabling the creation of structurally diverse and pharmacologically active compounds. Concurrent developments in computational strategies have further enhanced macrocycle design, providing valuable insights into structural optimization and predicting molecular properties essential for therapeutic efficacy. Additionally, a deeper understanding of macrocycles’ conformational adaptability, especially their ability to internally shield polar functionalities to improve membrane permeability, has significantly informed their rational design. This review discusses recent innovations in synthetic and computational methodologies that have advanced macrocycle drug discovery over the past five years. It emphasizes the importance of integrating these strategies to overcome existing challenges, illustrating how their synergy expands the therapeutic potential and chemical diversity of macrocycles. Selected case studies underscore the practical impact of these integrated approaches, highlighting promising therapeutic applications across diverse biomedical targets. Full article
(This article belongs to the Special Issue Advances in the Synthesis and Application of Heterocyclic Compounds)
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