Five and Six-Membered Heterocyclic Compounds and Their Therapeutic Potential

Dear Colleagues,

Five and six-membered heterocyclic compounds are appealing targets found in a wide range of drug structures and have piqued the interest of medicinal chemists worldwide.

Many heterocyclic scaffolds can be considered as privilege structures. Nitrogen, oxygen, and sulphur are the most common heteroatoms found in heterocyclic compounds. According to statistics, a heterocycle is present in more than 85% of all biologically active chemical entities. Five-member heterocycles are classified as imidazoles, oxadiazoles, pyrazoles, thiadiazoles, triazoles, tetrazoles, and others depending on the number, nature, and arrangement of heteroatoms. They are important structural units in many pharmaceutical drugs. They can be found as an isolated ring or as a fused ring (e.g., benzimidazole, benzisoxazole, etc.). Similarly, six-membered heterocycles are classified as pyridine, pyrazine, dioxane, pyrimidine etc.

The oxadiazole ring can be found in drugs such as prenoxdiazine (cough suppressant), raltegravir (anti-HIV), and others, while pyrazoles heterocyle can be found in many NSAIDs (such as phenylbutazone, celecoxib, and others), antigout (sulfinpyrazole), and antipyretics (Aminophenazone). The thiadiazole ring is found in acetazolamide, a diuretic and carbonic anhydrase inhibitor, and the imidazole ring is found in histamines, phenytoin, and other drugs. The six-membered pyridine (e.g. isoniazid) and pyrazine (e.g. pyrazinamide) rings are found in antitubercular drugs.

This thematic issue deals with:

1. Therapeutic potentials (anticancer, antitubercular, antimicrobial, anti-inflammatory, antioxidant, antiviral, etc.) of five and six-membered heterocycles.
2. Conventional, microwave assisted and ultrasound mediated synthesis of five and six-membered heterocycles.
3. The novel catalytic syntheses of five and six-membered heterocycles.
4. Solvent free and green synthesis of five and six-member heterocycles.
5. In-silico, molecular docking, molecular dynamics, and computational studies of five and six-membered heterocycles.
6. Spectral characterization and DFT (HOMO and LUMO) studies of five and six-membered heterocycles.
7. Structural modification of natural isolates into their semi-synthetic analogues (five and six-membered heterocycles).

Thus, the current Special Issue aims to collect and present recent advances in conventional and green synthesis, as well as their therapeutic applications related to five and six-membered heterocyclic compounds (communications, full papers, and reviews).

Prof. Dr. Mohamed Jawed Ahsan
Dr. Faizul Azam
Dr. Md. Afroz Bakht
Guest Editors

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