Thiadiazole Scaffold Research Articles

Insight from molecular modeling and ADMET analysis: Design, synthesis and in vitro acetylcholinesterase and butyrylcholinesterase assessment of thiazolidinone containing benzoxazole hybrids derivatives

Alzheimer's disease (AD) is a brain disorder medically defined as loss of memory and analytical reasoning abilities of an infected person. The adult or aged peoples are more likely to be adversely affected by this disease. Following this prospect, this study is conducted to synthesize a novel class of (Z)-2-(((Z)-2-(benzo[d]oxazol-2-ylthio)-1-phenylethylidene)hydrazono)-3-phenylthiazolidin-4-one based derivatives and evaluate its performance towards the treatment of AD. This study showed the better results when compared to the inhibition potential of the standard drug Donepezil against AChE (IC50= 4.10 ± 1.05 µM) and against BuChE (IC50=6.59 ± 1.63 µM), the inhibition potential shown by benzimidazole based thiadiazole scaffolds against the targeted enzymes is of wide range. The inhibition potential of all the scaffolds against AChE ranged from 2.89 ± 0.65 µM to 19.04 ± 0.49 µM and against BuChE ranged from 3.70 ± 0.98 µM to 23.19 ± 0.71 µM. Moreover, to investigate the binding interaction of effective scaffolds against the active sites of AChE and BuChE, molecular docking studies were carried out and the analysis data evaluated the substantial binding interaction of scaffolds against the targeted enzymes. The structural characteristic of each scaffold is determined by using different spectroscopic techniques. In this work only three analogues found to be the most active having the observed IC50 values 7d, 3.05 ± 0.19 µM, 2.90 ± 0.87 µM(for BuChE), 7g, 3.88 ± 0.32 µM(for AChE), 4.98 ± 0.54 µM(for BuChE), 7k 2.89 ± 0.65 µM(for AChE), 3.70 ± 0.98 µM(for BuChE). Furthermore, the selected analogues considered for In-Vivo and cytotoxic study as well as structure modification carried out in search of more active analogues.

Design, Synthesis, Antimicrobial Activity and Molecular Docking of Novel Pyridine, Thiophene, and Thiadiazole Scaffolds Utilizing 2-Cyano-N-(4-(1-(2-(2-cyanoacetyl)hydrazineylidene)ethyl)phenyl)acetamide

An efficient protocol is reported for synthesizing arylidene adducts, pyridine derivatives, in excellent yields by treating 2-cyano-N-(4-(1-(2-(2-cyanoacetyl) hydrazineylidene) ethyl)phenyl)acetamide with quinoline-3-carbaldehydes, 2-arylidenemalononitriles, and acetylacetone in EtOH, respectively. In addition, dithiadiazole and dithiophene adducts were synthesized from one pot reaction using phenyl isothiocyanate, and either hydrazonyl chloride or 2-bromo-1-(5-methyl-1-(p-tolyl)-1H-1,2,3-triazole-4-yl)ethan-1-one in DMF containing potassium hydroxide. The structure of novel products was elucidated using spectroscopic data and elemental analyses. The synthesized compounds were evaluated for their antimicrobial activities. The compounds showed antibacterial and antifungal activities against the tested G-ve and G+ve bacteria and against the tested fungi. The MIC was mostly in the range of 100-500 μg/mL. Molecular docking was used to analyse interactions between the compounds and antimicrobial target proteins. The molecular docking simulation showed lower binding energy with different types of interaction at the active site of Sterol 14-demethylase of C. albicans, Fdc1 proteins of A. niger, DNA Gyrase of E. coli, and LasR, an activator of exotoxin. An expression of P. aeruginosa indicates that these compounds could inhibit the enzyme and cause promising antimicrobial effects.

Synthesis and Molecular Docking of some new Thiazolidinone and Thiadiazole Derivatives as Anticancer Agents.

New sets of functionalized thiazolidinone and thiadiazole derivatives were synthesized, and their cytotoxicity was evaluated on HepG2, MCF-7, HTC-116, and WI38 cells. The synthetic approach is based on the preparation of 4-(4-acetamidophenyl)thiosemicarbazide (4) and their thiosemicarbazones 5 a-e, which are converted to the corresponding thiazoldin-4-one compounds 6 a-e upon cyclization with ethyl bromoacetate. The thiadiazole compounds 9 and 12 were obtained by reacting 4-(4-acetamidophenyl)thiosemicarbazide with isothiocyanates and/or ethyl 2-cyano-3,3-bis(methylthio)acrylate, respectively. The thiazolidinone compounds 6 c and 6 e exhibited strong cytotoxicity against breast cancer cells, with an IC50 (6.70±0.5 μM) and IC50 (7.51±0.8 μM), respectively, very close to that of doxorubicin (IC50: 4.17±0.2 μM). In addition, the anti-cancer properties of the tested thiazolidinone and thiadiazole scaffolds were further explored by the molecular docking program (MOE)-(PDB Code-1DLS). Compounds 5 d, 5 e, 6 d, 6 e, and 7 have the best binding affinity, ranging from -8.5386 kcal.mol-1 to -8.2830 kcal.mol-1.

Fungicidal Activity of New Pyrrolo[2,3-d]thiazoles and Their Potential Action on the Tryptophan Metabolic Pathway and Wax Biosynthesis.

The main challenge in the development of agrochemicals is the lack of new leads and/or targets. It is critical to discover new molecular targets and their corresponding ligands. YZK-C22, which contains a 1,2,3-thiadiazol-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazole skeleton, is a fungicide lead compound with broad-spectrum fungicidal activity. Previous studies suggested that the [1,2,4]triazolo[3,4-b][1,3,4]thiadiazole scaffold exhibited good antifungal activity. Inspired by this, a series of pyrrolo[2,3-d]thiazole derivatives were designed and synthesized through a bioisosteric strategy. Compounds C1, C9, and C20 were found to be more active against Rhizoctonia solani than the positive control YZK-C22. More than half of the target compounds provided favorable activity against Botrytis cinerea, where the EC50 values of compounds C4, C6, C8, C10, and C20 varied from 1.17 to 1.77 μg/mL. Surface plasmon resonance and molecular docking suggested that in vitro potent compounds C9 and C20 have a new mode of action instead of acting as pyruvate kinase inhibitors. Transcriptome analysis revealed that compound C20 can impact the tryptophan metabolic pathway, cutin, suberin, and wax biosynthesis of B. cinerea. Overall, pyrrolo[2,3-d]thiazole is discovered as a new fungicidal lead structure with a potential new mode of action for further exploration.

A review on synthetic approaches for obtaining and chemical modification of 1,2,4-triazolo[3,4-b][1,3,4]thiadiazole based heterocyclic compounds

Triazolo[3,4-b]thiadiazoles are a class of heterocyclic compounds, which have attracted great interest in medicinal chemistry owing to their wide range of pharmacological activities. A number of triazoles fused to thiadiazoles are incorporated into a wide variety of therapeutically important compounds possessing a broad spectrum of biological activities. Considering such a significant pharmacological potential, as well as wide synthetic possibilities triazolo-thiadiazoles have received considerable attention from scientific community and are extensively used for construction of prospective drug-likes molecules. In this review, we summarized the literature data about the main synthetic approaches for obtaining condensed heterocyclic compounds based on triazolo[3,4-b][1,3,4]thiadiazole scaffold as promising objects for modern bioorganic and medicinal chemistry.

Synthesis, X-ray Crystal Structure, and Antimicrobial Studies of New Quinazolin-4(3H)-one Derivatives Containing the 1,2,4-Triazolo[3,4-b][1,3,4]thiadiazole Moiety and 4-Piperidinyl Linker.

A total of 35 new quinazolinone derivatives bearing the 1,2,4-triazolo[3,4-b][1,3,4]thiadiazole scaffold and the 4-piperidinyl linker were designed, prepared, and assessed for their antibacterial and antifungal activities. Among these derivatives, the chemical structure of compound F5 was clearly verified via single-crystal X-ray diffraction analysis. The experimental results revealed that some of the compounds displayed good even excellent inhibitory effects toward the tested phytopathogenic bacteria. For instance, compound F33 was capable of strongly inhibiting Xanthomonas oryzae pv. oryzae (Xoo) in vitro with an EC50 (half-maximal effective concentration) value of 4.1 μg/mL, about 16-fold more effective than the commercialized bactericide bismerthiazol. Significantly, this compound also effectively suppressed the proliferation of Xoo in the potted rice plants, showing a good in vivo protection efficacy of 47.6% at 200 μg/mL. Subsequently, the antibacterial mechanisms of compound F33 were explored by means of different biophysical and biochemical methods. Last, some of the compounds were found to possess relatively good antifungal activities in vitro, like compound F19 against Phytophthora nicotianae (with an inhibition rate of 67.2% at 50 μg/mL). In a word, the current experimental results imply that the 4-piperidinyl-bridged quinazolinone-1,2,4-triazolo[3,4-b][1,3,4]thiadiazole derivatives possess potential as lead compounds for developing more efficient anti-Xoo bactericides.

Greener Approaches for Synthesis of Bioactive Thiadiazole Scaffolds

Abstract: Thiadiazole is a paradigm of five membered heterocyclic compound that contains two nitrogens and one sulphur as heteroatoms with molecular formula C2H2N2S. Thiadiazole is mainly present in four isomeric forms such as 1,2,3-thiadiazole, 1,2,4-thiadiazole, 1,2,5-thiadiazole and 1,3,4-thiadiazole. Out of these isomers, 1,3,4-thiadiazole has attracted remarkable attention in the field of medicinal chemistry. Some of the drugs containing 1,3,4-thiadiazole moiety are used clinically and are available in the market including Sulphamethizole (Antibacterial), Acetazolamide (Diuretic), Azetepa (Antineoplastic), Cefazolin (Antibiotic), Megazol (Antiprotozoal), Atibeprone (anti-depressant). Several greener approaches are applied for the synthesis of thiadiazole scaffolds including microwave irradiation, ultrasonic irradiation, grinding, ball milling technique, etc. These methods are eco-friendly, nonhazardous, reproducible, and economical approach. Based on these Green chemistry approaches, thiadiazole derivatives are synthesized from thiosemicarbazide. The functionalization of these heterocyclic compounds generates thiadiazole derivatives with diverse chemical structures. This review covers green synthesis, biological potentials, and structure activity relationship study of thiadiazole analogs.

Thiadiazole - A promising structure in design and development of anti-Alzheimer agents.

The design and development of effective multitargeted agents in treating Alzheimer disease (AD) has always been a hot topic in the field of drug discovery. Since AD is a multifactorial disorder, various key hidden players such as deficit of acetylcholine (ACh), tau-protein aggregation, and oxidative stress have been associated with the incidence and progress of AD. In pursuit of improving efficacy and expanding the range of pharmacological activities of current AD drugs, the molecular hybridization method is also used intensively. Five-membered heterocyclic systems such as thiadiazole scaffolds have previously been shown to have therapeutic activity. Thiadiazole analogs as an anti-oxidant compound have been known to include a wide range of biological activity from anti-cancer to anti-Alzheimer properties. The suitable pharmacokinetic and physicochemical properties of the thiadiazole scaffold have introduced it as a therapeutic target in medicinal chemistry. The current review portrays the critical role of the thiadiazole scaffold in the design of various compounds with potential effects in the treatment of Alzheimer's disease. Furthermore, the rationale used behind hybrid-based design strategies and the outcomes achieved through the hybridization of Thiadiazole analogs with various core structures have been discussed. In addition, the data in the present review may help researchers in the design of new multidrug combinations that may provide new options for the treatment of AD.

Investigation of Novel Mucorales Fungal Inhibitors: Synthesis, In‐Silico Study and Anti‐Fungal Potency of Novel Class of Coumarin‐6‐Sulfonamides‐Thiazole and Thiadiazole Hybrids

AbstractA series of coumarin‐6‐sulfonamides derivatives bearing a thiazole and thiadiazole scaffold were synthesized, their chemical structures were inferred from correct spectral and microanalytical data. All the newly synthesized compounds have been screened for their ability to prevent the proliferation of Mucor racemosus, Syncephalastrum racemosum in vitro. The most potent compounds were chosen to determine the MIC value in compared to the standard antifungal agent (Posaconazole). Remarkably, an excellent anti‐mucormycosis was obtained by compounds known as 8 d, and 8 d with MIC value close to that observed by the standard Posaconazole. Amolecular. Docking study was performed where compounds 3, 5 a, 5 d, 8 d, 8 e, 10 c and 10 e were docked against the fungal enzyme sterol 14‐alpha demethylase (CYP51) “PDB id: 5FSA”. In silico, compounds 8 d & 8 e showed the best docking by forming 3H bonds and free binding energy (12.2 & 12 K cal/mol) close to the binding energy (12.2 K cal/mol) of the co‐crystalized inhibitor (posconazol. From wet lab and dry lab results, one can recommend compounds 8 d & 8 e for further antifungal drug development.

Biological activity of oxadiazole and thiadiazole derivatives.

The 5-membered oxadiazole and thiadiazole scaffolds are the most privileged and well-known heterocycles, being a common and essential feature of a variety of natural products and medicinal agents. These scaffolds take up the center position and are the core structural components of numerous drugs that belong to different categories. These include antimicrobial, anti-tubercular, anti-inflammatory, analgesic, antiepileptic, antiviral, and anticancer agents. In this review, we mostly talk about the isomers 1,2,4-oxadiazole and 1,3,4-thiadiazole because they have important pharmacological properties. This is partly because they are chemical and heat resistant, unlike other isomers, and they can be used as bio-isosteric replacements in drug design. We are reviewing the structural modifications of different oxadiazole and thiadiazole derivatives, more specifically, the anti-tubercular and anticancer pharmacological activities reported over the last 5 years, as we have undertaken this as a core area of research. This review article desires to do a thorough study and analysis of the recent progress made in the important biological isomers 1,2,4-oxadiazole and 1,3,4-thiadiazol. This will be a great place to start for future research.Key points • Five-membered heterocyclic compound chemistry and biological activity recent survey. • Synthesis and pharmacological evolution of 1,2,4-oxadiazole and 1,3,4-thiadiazole are discussed in detail. • The value and significance of heterocyclic compounds in the field of drug designing are highlighted. Supplementary InformationThe online version contains supplementary material available at 10.1007/s00253-022-11969-0.

Synthesis and Anticancer Activity of Thiadiazole Containing Thiourea, Benzothiazole and Imidazo[2,1-b][1,3,4]thiadiazole Scaffolds.

A great array of nitrogen-containing heterocyclic rings were being extensively explored for their functional versatility in the field of medicine, especially in anticancer research. 1,3,4- thiadiazole is one of such heterocyclic rings with promising anticancer activity against several cancer cell lines, inhibiting diverse biological targets. The 1,3,4-thiadiazole, when equipped with other heterocyclic scaffolds, has displayed enhanced anticancer properties. The thiourea, benzothiazole, imidazo[2,1,b][1,3,4]-thiadiazoles are such potential scaffolds with promising anticancer activity. A new series of 5-substituted-1,3,4-thiadiazoles linked with phenyl thiourea, benzothiazole and 2,6-disubstituted imidazo[2,1-b][1,3,4]thiadiazole derivatives were synthesized and tested for invitro anticancer activity on various cancer cell lines. The National Cancer Institute's preliminary anticancer screening results showed compounds 4b and 5b having potent antileukemic activity. Compound 4b selectively showed 32 percent lethality on Human Leukemia-60 cell line. The docking studies of the derivatives on aromatase enzyme (Protein Data Bank: 3S7S) have shown reversible interactions at the active site with good docking scores comparable to Letrozole and Exemestane. Furthermore, the selected derivatives were tested for anticancer activity on HeLa cell line based on the molecular docking studies. Compounds 4b and 5b showed effective inhibition equivalent to Letrozole. These preliminary biological screening studies have given positive anticancer activity for these new classes of derivatives. An additional research study like the mechanism of action of the anticancer activity of this new class of compounds is necessary. These groundwork studies illuminate a future pathway for research of this class of compounds enabling the discovery of potent antitumor agents.

Synthesis and In Vitro Biological Activity Evaluation of Novel Imidazo [2,1-B][1,3,4] Thiadiazole as Anti-Alzheimer Agents

Background: Considering that AD is multifactorial in nature, novel series of imidazo [2,1-b][1,3,4] thiadiazole derivatives were designed to address the basic factors responsible for the disease. <p> Methods: These compounds were investigated as inhibitors of beta-site APP cleaving enzyme 1, acetylcholinesterase and butyryl cholinesterase. <p> Results: The BACE1 inhibitory results indicated that nitro phenyl substituted derivatives of imidazo [2,1-b][1,3,4] thiadiazole scaffold (R2 = m-NO2) demonstrated superior BACE1 inhibitory activity compared to other substituted moieties. In the BuChE assay, compounds 4h and 4l carrying meta NO2 at R2 of phenyl ring turned out to be potent inhibitors. <p> Conclusion: In conclusion, these novel synthesized derivatives seem to be promising anti-Alzheimer agents.

Фармакофорне моделювання діуретичної активності похідних 1,3-тіазолу та 1,3,4-тіадіазолу

Фармакофорне моделювання є одним з перспективних напрямів комп’ютерної підтримки розробки ліків (Computer-Aided Drug Design). Цей метод дозволяє встановити набір та взаємне розташування специфічних молекулярних фрагментів, які необхідні для прояву біологічної активності. Мета дослідження – фармакофорне моделювання похідних 1,3-тіазолу та 1,3,4-тіадіазолу для цілеспрямованого пошуку потенційних діуретиків. Для моделювання фармакофора, відповідального за прояв діуретичної активності в ряду досліджених сполук, використовували комп’ютерну програму MOE (Molecular Operating Environment). Фармакофорне моделювання ряду похідних тіазолу та тіадіазолу як потенційних діуретиків, активність яких встановлена in vivo, дало змогу виділити можливий фармакофор, що складається з ароматичного кільця, двох проекцій акцептора водневого зв’язку та однієї проекції донора водневого зв’язку. Точність класифікації активних і неактивних сполук даною моделлю становить 0,74, дана модель може надалі застосовуватись для in silico скринінгу молекулярних баз даних з метою ідентифікації віртуальних хітів. Порівнюючи узгодженість N-(5-метил-1,3,4-тіадіазол-2-іл)пропанаміду та ацетазоламіду з розробленою фармакофорною моделлю, визначено модулюючий вплив замісника в 5-му положенні тіадіазольного кільця на силу діуретичного ефекту in vivo. Отримані дані свідчать, що замісники з позитивним індуктивним і мезомерним ефектом у цьому положенні можуть сприяти кращій афінності досліджуваних молекул до їхньої біомішені (якою з найбільшою ймовірністю є карбоангідраза). Подальші модифікації фрагментів у 5-му положенні тіадіазольного скаффолду є перспективним напрямом для розширення бібліотеки потенційних діуретиків.

Synthesis, molecular docking, antimicrobial evaluation, and DNA cleavage assay of new thiadiazole/oxadiazole ciprofloxacin derivatives

Herein we report the synthesis of new N-4-piperazinyl thiadiazole and oxadiazole ciprofloxacin derivatives and their antibacterial and antimycobacterial activities. Although thiadiazole ciprofloxacin derivatives compound showed broad spectrum antibacterial activity against all the tested strains either Gram-positive or Gram-negative organisms, the oxadiazole derivatives exhibited weaker antibacterial and antimycobacterial activities than thiadiazole derivatives against most of the tested strains compared with the reference ciprofloxacin. Moreover, the antimycobacterial screening revealed that compounds which containing thiadiazole scaffold potently inhibited Mycobacterium smegmatis at MIC of 1.56 and 3.13, respectively, and modestly inhibited the drug-resistant strains. DNA cleavage assay revealed that thiadiazole ciprofloxacin derivatives inhibited supercoil relaxation, albeit to a lesser extent than ciprofloxacin, and it also increased the amount of nicked substrate produced.

Synthesis of N-pyrimidin[1,3,4]oxadiazoles and N-pyrimidin[1,3,4]-thiadiazoles from 1,3,4-oxadiazol-2-amines and 1,3,4-thiadiazol-2-amines via Pd-catalyzed heteroarylamination

An efficient and practical procedure was developed to prepare various N-pyrimidin[1,3,4]oxadiazole and thiadiazole scaffolds using a Buchwald-type coupling. The products of this reaction are otherwise difficult to access and could be used as building blocks in drug design.

Crystal structure of the Eg5 - K858 complex and implications for structure-based design of thiadiazole-containing inhibitors

The thiadiazole scaffold is an important core moiety in a variety of clinical drug candidates targeting a range of diseases. For example, the 2,4,5-substituted 1,3,4-thiadiazole scaffold is present in a lead compound and at least two clinical candidates targeting the human motor protein Eg5, against neoplastic diseases. An inhibitor named K858 has in vivo activity in various mouse xenografts whereas the clinical candidates (S)-ARRY-520 and (R)-Litronesib have entered clinical trials with the former one in phase III clinical trials either alone or in combination with a proteasome inhibitor against relapsed/refractory multiple myeloma. Astonishingly, structural data are lacking for all thiadiazole-containing Eg5 inhibitors. Here we report the structure determination of two crystal forms of the ternary Eg5-ADP-K858 complex, locking the motor in the so-called final inhibitor bound state, thus blocking ADP release, a crucial stage for Eg5 activity. K858 acts at the established allosteric inhibitor-binding pocket formed of helix α2, loop L5 and helix α3. The structure of the complex has far reaching consequences for thiadiazole containing Eg5 inhibitors. For example, we could rationalise the structure-activity relationship in the crucial 5-position of the thiadiazole scaffold and the complex will serve in the future as a basis for strucutre-based drug design.

The facile and efficient organocatalytic platform for accessing 1,2,4-selenadiazoles and thiadiazoles under aerobic conditions

The first organocatalytic approach towards synthesis of rarely explored 1,2,4-selenadiazole and thiadiazole scaffolds have been devised using corresponding carboxamides as substrates. The transformations were realized using two distinct conditions in the presence of catalytic vitamin B3 or thiourea under aerobic conditions. Developed methods overcome the associated limitations of previous reported approaches and the desired products were obtained in high yields and selectivity without the formation of toxic side-products.

Microwave-Assisted Facile Synthesis, Anticancer Evaluation and Docking Study of N-((5-(Substituted methylene amino)-1,3,4-thiadiazol-2-yl)methyl) Benzamide Derivatives.

In the present work, 12 novel Schiff’s bases containing a thiadiazole scaffold and benzamide groups coupled through appropriate pharmacophore were synthesized. These moieties are associated with important biological properties. A facile, solvent-free synthesis of a series of novel 7(a–l) N-((5-(substituted methylene amino)-1,3,4-thiadiazol-2-yl)methyl) benzamide was carried out under microwave irradiation. Structures of the synthesized compounds were confirmed by IR, NMR, mass spectral study and elemental analysis. All the synthesized hybrids were evaluated for their in vitro anticancer activity against a panel of four human cancer cell lines, viz. SK-MEL-2 (melanoma), HL-60 (leukemia), HeLa (cervical cancer), MCF-7 (breast cancer) and normal breast epithelial cell (MCF-10A) using 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay method. Most of the synthesized compounds exhibited promising anticancer activity, showed comparable GI50 values comparable to that of the standard drug Adriamycin. The compounds 7k, 7l, 7b, and 7a were found to be the most promising anticancer agents in this study. A molecular docking study was performed to predict the probable mechanism of action and computational study of the synthesized compounds 7(a–l) was performed to predict absorption, distribution, metabolism, excretion and toxicity (ADMET) properties, by using QikProp v3.5 (Schrödinger LLC). The results showed the good oral drug-like behavior of the synthesized compounds 7(a–l).

Thiadiazoles: the appropriate pharmacological scaffolds with leishmanicidal and antimalarial activities: a review.

Leishmaniasis and malaria are serious public health problems in tropical and sub-tropical regions worldwide. Development of drug-resistant strains has disrupted efforts to control the spread of these diseases in the world. The conventional antiparasitic chemotherapy still suffers from side effects and drug resistance. Therefore, the development of novel antimalarial and leishmanicidal drugs remains a critical topic to combat against these diseases. Five-membered heterocyclic systems have possessed antiparasitic activity such as thiadiazole scaffold which is a prevalent and an important heterocyclic ring. For this purpose, the authors introduce a series of synthetic thiadiazole derivatives with antileishamanial activity. Also, the authors searched a number of sources and articles to find thiadiazole derivatives with antileishamnial and antimalarial activity. Then all of the findings were reviewed. 5-nitroheteroaryl-1,3,4-Thiadiazole derivatives with different substituents at position 2 of the thiadiazole ring (8, 10-11) presented the best antileishmanial activity with low toxicity compared with reference drug. Also, 1,3,4-thiadiazole-2-sulfonamide derivative (18) showed excellent inhibitory activity against pfCA as a special enzyme in Plasmodium falciparum. Thiadiazole scaffold has the suitable physicochemical and pharmacokinetic properties and still stays as a therapeutic target for the development of a novel lead in the medicinal chemistry. Therefore, the current review provides a brief summary of medicinal chemistry of thiadiazole ring and introduces novel leads possessing this nucleus with antimalarial and antileishmanial activities.

Identification of the minimum PAR4 inhibitor pharmacophore and optimization of a series of 2-methoxy-6-arylimidazo[2,1-b][1,3,4]thiadiazoles

This letter describes the further deconstruction of the known PAR4 inhibitor chemotypes (MWs 490–525 and with high plasma protein binding) to identify a minimum PAR4 pharmacophore devoid of metabolic liabilities and improved properties. This exercise identified a greatly simplified 2-methoxy-6-arylimidazo[2,1-b][1,3,4]thiadiazole scaffold that afforded nanomolar inhibition of both activating peptide and γ-thrombin mediated PAR4 stimulation, while reducing both molecular weight and the number of hydrogen bond donors/acceptors by ∼50%. This minimum PAR4 pharmacophore, with competitive inhibition, versus non-competitive of the larger chemotypes, allows an ideal starting point to incorporate desired functional groups to engender optimal DMPK properties towards a preclinical candidate.