Synthesis, molecular modeling studies and evaluation of antifungal activity of a novel series of thiazole derivatives

Synthesis of 2-Amino-4, 5-Diarylthiazole Derivatives and Evaluation of Their Anti-Candida Albicans Activity

The thiazole heterocycle is one of the most common moieties found in various drugs. Using 2-aminothiazole as the core structure, the amino group was functionalized with an amide. As a result, 30 trisubstituted 2-amino-4, 5-diarylthiazole derivatives were synthesized, with different substitutions introduced at the C2, C4, and C5 positions. The anti-Candida albicans biological activities of these synthetic compounds on five kinds of Candida albicans at different concentrations were detected by the microdilution method. In the first round, four derivatives of 2-amino-4, 5-diarylthiazole exhibited moderate anti-Candida albicans activity. Among them, 4a8 was chosen to be subjected to a demethylation process. Thus, 5a8 was synthesized successfully, giving anti-Candida albicans activity (MIC80 = 9 μM) similar to that of a typical antifungal drug, fluconazole. To understand the mechanism of anti-Candida albicans, molecular docking of the most active 5a8 against four target proteins of anti-Candida albicans, such as glutamine-fructose-6-phosphoamidamitransferase (GFAT), protein kinase (Yck2), heat-shock protein 90 (Hsp90), and lanosterol 14a-demethylase (CYP51) was carried out. Our research will provide an experimental basis and theoretical guidance for the further design of a new aminothiazole-leading pharmaceutical molecule.

Thiazole Derivatives as Promising Candidates for Cryptococcosis Therapy

Cryptococcosis is a severe fungal infection primarily caused by two encapsulated yeasts: Cryptococcus neoformans and C. gattii. The most significant complication is cryptococcal meningitis, where the fungus crosses the blood-brain barrier, leading to a severe brain infection. Current treatments, which include amphotericin B and flucytosine or fluconazole, are often toxic and not very effective. Therefore, there is a pressing need for new antifungal agents. This study screened 30 thiazole derivatives for their antifungal activity against Cryptococcus and their toxicity to brain cells. Four compounds (RN86, RN88, RJ37, and RVJ42) showed particularly strong effects. These compounds reduced ergosterol levels in the fungal membrane and inhibited its ability to cross the blood-brain barrier. Notably, RN86 and RVJ42 improved survival rates in a mouse model of cryptococcosis by lowering the fungal load in the lungs and brain. These findings suggest that these derivatives could be promising treatments for pulmonary and neurocryptococcosis.

Hydralazine and Hydrazine Derivatives: Properties, Applications, and Repositioning Potential

The investigation of new drugs is slow and costly. Drug repositioning, like with Hydralazine (HDZ), an old antihypertensive, can accelerate the process. HDZ and its hydrazonic derivatives exhibit diverse biological activities, promising for new drugs. This review explores HDZ's repositioning potential and its derivatives' applications in various biological activities. It identified 70 relevant articles through database searches. HDZ shows potential in neurology, oncology, nephrology, and gynecology, with clinical trials up to Phase III. Hydralazine-valproate, marketed in Mexico, proves effective in combination with chemotherapy. Hydrazonic derivatives offer broad applications in medicine. Studying their structure-activity relationship can enhance efficacy. This review summarizes their properties and pharmacological activities succinctly.

One-Pot Multicomponent Synthesis of Fully Substituted 1,3-Thiazoles Appended with Naturally Occurring Lawsone

Lawsone is a popular bioactive natural product. 1,3-Thiazoles are also widely distributed in many natural products, FDA-approved drugs, and functional materials. We report herein the first synthesis of naturally occurring lawsone-linked fully substituted 1,3-thiazoles in a one-pot multicomponent reaction (MCR) of arylglyoxals, lawsone, and thiobenzamides in acetic acid at 90 °C, affording lawsone-1,3-thiazole hybrids in excellent yields in short reaction times. The advantages of the present method include facile, robust, and easy access to the medicinally relevant diverse array of fully substituted lawsone-1,3-thiazole hybrids, easy isolation of the product by filtration, thereby avoiding column-chromatographic purifications, short reaction time, and metal- and catalyst-free and gram-scale synthesis.

Novel Isoxazole-Based Antifungal Drug Candidates

Microbiological communities have a significant impact on health and disease. Candida are ubiquitous fungal pathogens that colonize the mucosal surfaces of the genital, urinary, respiratory, and gastrointestinal tracts, as well as the oral cavity. If the immune system is inadequate, then Candida infections may pose a significant threat. Due to the limited number of clinically approved drugs for the treatment of Candida albicans-based infections and the rapid emergence of resistance to the existing antifungals, a novel series of isoxazole-based derivatives was synthesized and evaluated in vitro for their anti-Candida potential. Two compounds, PUB14 and PUB17, displayed selective antifungal activity without negatively affecting beneficial microbiota, such as Lactobacillus sp., at the same time. Moreover, these compounds exhibited significantly lower cytotoxicity in comparison to conventionally applied local antimicrobial (octenidine dihydrochloride), indicating their potential for safe and effective clinical application in conditions such as vulvovaginal candidiasis. The selective antifungal activity of PUB14 and PUB17 against C. albicans, coupled with its absence of antibacterial effects and minimal cytotoxicity towards HeLa cells, suggests a targeted mechanism of action that warrants further investigation. Consideration of the need to search for new antifungal agents and the discovery of an antifungal potential drug that does not inhibit lactobacilli growth could be a potential strategy to prevent and combat vulvovaginal candidiasis. This striking capacity to eradicate biofilm formed by Candida reveals a new approach to eradicating biofilms and sheds light on isoxazole-based derivatives as promising anti-biofilm drugs.

Effect of curcumin and three analogues on pre-osteoblast cells' viability, differentiation, and gene expression

Curcumin, found in turmeric rhizomes (Curcuma longa L.), has been widely studied for its potential health benefits, including anti-inflammatory, antioxidant, and wound-healing properties. However, due to its low bioavailability and unfavorable pharmacokinetics, analogous compounds have been developed to obtain better biopharmaceutical characteristics and enhanced biological effects. In this study, we evaluated the activity of curcumin and three of its synthetic analogues (DMAD, DMAM, and RI75) on the viability and differentiation of a pre-osteoblastic cell line (MC3T3-E1). We also assessed the expression of key genes involved in tissue regeneration: vascular endothelial growth factor (vegf), stromal-derived growth factor 1 (SDF-1/CXCL12), and runt-related transcription factor 2 (runx2). The cells were treated with curcumin and the three analogues at concentrations of 10, 30, or 50 μM. All tested analogues and curcumin exhibited moderate to no cell toxicity compared to the cells treated under standard conditions across all concentrations after 24, 48, and 72 hours. Only the RI75 analogue showed upregulation of SDF-1, a crucial factor in tissue regeneration. Compared to curcumin, the DMAM and RI75 analogues also upregulated runx2 and vegf, both associated with osteodifferentiation. The RI75 analogue demonstrated greater mineralization than curcumin, and both promoted more nodule formation than the untreated control. Our data suggest that the curcumin analogue RI75 at 50 μM presents similar toxicity but enhanced biological activity compared to natural curcumin, making it a promising substance for material biomodifications.

Novel Essential Oil-Based Thiosemicarbazone Compounds as Potential Fungicides in Controlling Postharvest Diseases of Citrus Fruit

To develop novel fungicides for controlling postharvest fungal diseases in citrus fruits, 12 essential oil (EO)-based thiosemicarbazones compounds, termed hydrazine-carbothioamide, were prepared according to the condensation method. In vitro assays showed that compound 13j exhibited the strongest antifungal activity (minimum inhibitory concentration [MIC] = minimum fungicidal concentration [MFC] = 0.0125 mg/mL) against Penicillium digitatum. An in vivo study revealed that 5 × MFC of compound 13j can effectively mitigate the green mold incidence of citrus fruit inoculated with P. digitatum, as well as fruit rot during natural storage, at a level comparable to that of the chemical fungicide prochloraz. Throughout this process, fruit quality was maintained. The hemolysis assay showed that these thiosemicarbazone compounds have good biocompatibility and that their safety is comparable to that of prochloraz. The antifungal activity of compound 13j was attributed to membrane damage, as confirmed using scanning electron microscopy (SEM), Calcofluor white (CFW) staining, propidium iodide (PI) staining, Fourier transform-infrared (FT-IR) spectroscopy, optical density (OD)260, and relative conductivity assays. Collectively, our results indicate that compound 13j can be used as an antifungal agent to control the postharvest decay of citrus fruits.

Design, Synthesis, Investigation, and Biological Activity Assessments of (4-Substituted-Phenyl)-N-(3-morpholinopropyl)-3-phenylthiazol-2(3H)-imine Derivatives as Antifungal Agents

In this study, a series of novel thiazol-2(3H)-imine (2a-2j) were designed, synthesized, and characterized by means of 1H NMR, 13C NMR, and HRMS spectral analyses. In vitro antifungal activity was performed using a modified EUCAST protocol. Two of the synthesized compounds (2d and 2e) showed activity against Candida albicans and Candida parapsilosis. Compound 2e showed activity against C. parapsilosis (MIC50 = 1.23 μg/mL) for 48 h. This value is very similar to ketoconazole. The dynamic analysis of the potential compounds 2d and 2e revealed notable stability while interacting with the 14α-demethylase enzyme substrate. The absorption, distribution, metabolism, and excretion (ADME) studies of the candidate compound showed acceptable ADME parameter data and verified their drug-likeness characteristics. According to the results of this study, compound 4-(4-fluorophenyl)-N-(3-morpholinopropyl)-3-phenylthiazol-2(3H)-imine (2e) and its derivatives as 14α-demethylase inhibitors can be used as a new antifungal for further structural improvements and additional research.

An Insight into Rational Drug Design: The Development of In-House Azole Compounds with Antimicrobial Activity

Antimicrobial resistance poses a major threat to global health as the number of efficient antimicrobials decreases and the number of resistant pathogens rises. Our research group has been actively involved in the design of novel antimicrobial drugs. The blueprints of these compounds were azolic heterocycles, particularly thiazole. Starting with oxadiazolines, our research group explored, one by one, the other five-membered heterocycles, developing more or less potent compounds. An overview of this research activity conducted by our research group allowed us to observe an evolution in the methodology used (from inhibition zone diameters to minimal inhibitory concentrations and antibiofilm potential determination) correlated with the design of azole compounds based on results obtained from molecular modeling. The purpose of this review is to present the development of in-house azole compounds with antimicrobial activity, designed over the years by this research group from the departments of Pharmaceutical and Therapeutical Chemistry in Cluj-Napoca.

Design of potent tyrosinase inhibiting N-arylated-4-yl-benzamides bearing 2-aminothiazole-triazole bi-heterocycles: mechanistic insight through enzyme inhibition, kinetics and computational studies

By using a convergent methodology, a unique series of N-arylated 4-yl-benzamides containing a bi-heterocyclic thiazole-triazole core was synthesized and the structures of these hybrid molecules, 9a-k, were corroborated through spectral analyses. The in vitro studies of these multi-functional molecules demonstrated their potent mushroom tyrosinase inhibition relative to the standard used. The kinetics mechanism was exposed by lineweaver-burk plots which revealed that, 9c, inhibited mushroom tyrosinase non-competitively by forming an enzyme-inhibitor complex. The inhibition constant Ki calculated from Dixon plots for this compound was 0.016 μM. The computational study was also consistent with the experimental results and these molecules disclosed good results of all scoring functions and interactions, which suggested a good binding to mushroom tyrosinase. So, it was predicted from the inferred results that these molecules might be considered as promising medicinal scaffolds for the diseases associated with the over-expression of this enzyme.

Novel Thiazole Derivatives Containing Imidazole and Furan Scaffold: Design, Synthesis, Molecular Docking, Antibacterial, and Antioxidant Evaluation

Carbothioamides 3a,b were generated in high yield by reacting furan imidazolyl ketone 1 with N-arylthiosemicarbazide in EtOH with a catalytic amount of conc. HCl. The reaction of carbothioamides 3a,b with hydrazonyl chlorides 4a-c in EtOH with triethylamine at reflux produced 1,3-thiazole derivatives 6a-f. In a different approach, the 1,3-thiazole derivatives 6b and 6e were produced by reacting 3a and 3b with chloroacetone to afford 8a and 8b, respectively, followed by diazotization with 4-methylbenzenediazonium chloride. The thiourea derivatives 3a and 3b then reacted with ethyl chloroacetate in ethanol with AcONa at reflux to give the thiazolidinone derivatives 10a and 10b. The produced compounds were tested for antioxidant and antibacterial properties. Using phosphomolybdate, promising thiazoles 3a and 6a showed the best antioxidant activities at 1962.48 and 2007.67 µgAAE/g dry samples, respectively. Thiazoles 3a and 8a had the highest antibacterial activity against S. aureus and E. coli with 28, 25 and 27, 28 mm, respectively. Thiazoles 3a and 6d had the best activity against C. albicans with 26 mm and 37 mm, respectively. Thiazole 6c had the highest activity against A. niger, surpassing cyclohexamide. Most compounds demonstrated lower MIC values than neomycin against E. coli, S. aureus and C. albicans. A molecular docking study examined how antimicrobial compounds interact with DNA gyrase B crystal structures. The study found that all of the compounds had good binding energy to the enzymes and reacted similarly to the native inhibitor with the target DNA gyrase B enzymes' key amino acids.

Discovery of Lead 2-Thiazolylhydrazones with Broad-Spectrum and Potent Antifungal Activity

Opportunistic fungal infections represent a global health problem, mainly for immunocompromised individuals. New therapeutical options are needed since several fungal strains show resistance to clinically available antifungal agents. 2-Thiazolylhydrazones are well-known as potent compounds against Candida and Cryptococcus species. A scaffold-focused drug design using machine-learning models was established to optimize the 2-thiazolylhydrazone skeleton and obtain novel compounds with higher potency, better solubility in water, and enhanced absorption. Twenty-nine novel compounds were obtained and most showed low micromolar MIC values against different species of Candida and Cryptococcus spp., including Candida auris, an emerging multidrug-resistant yeast. Among the synthesized compounds, 2-thiazolylhydrazone 28 (MIC value ranging from 0.8 to 52.17 μM) was selected for further studies: cytotoxicity evaluation, permeability study in Caco-2 cell model, and in vivo efficacy against Cryptococcus neoformans in an invertebrate infection model. All results obtained indicate the great potential of 28 as a novel antifungal agent.

Evaluation of Cytotoxicity and Antifungal Activity of Friedelanes from Salacia elliptica Roots

Plants from Salacia genus are used in traditional medicine for a wide range of diseases. Previous studies reported bioactive pentacyclic triterpenoids from S. elliptica leaves and branches. In this study, the novel pentacyclic triterpenoid 7α,15α-dihydroxyfriedelan-3-one (1) was obtained from the roots of Salacia elliptica, along with seven known compounds: friedelan-3-one (2), friedelan-3β-ol (3), friedelan-1,3-dione (4), friedelan-3,15-dione (5), 15α-hydroxyfriedelan-3-one (6), 15α,26-dihydroxyfriedelan-3-one (7), and 26-hydroxyfriedelan-3,15-dione (8). Additionally, one steroid, spinasterol (9), was also identified. The chemical structures of all compounds were established through 1 H and 13 C-NMR. Compound 1 was analysed by additional 2D experiments (HMBC, HSQC, COSY, and NOESY) for complete elucidation. Furthermore, the cytotoxicity of compounds 2, 3, 6, 7 and 8 against the A549 lung cancer cells model was evaluated. The flow cytometry analysis revealed a significant cytotoxic activity similar to that exhibited by the triterpenoid lupeol. Additionally, compounds 2, 3, 6, and 7 were tested for in vitro antifungal activity against Candida, Cryptococcus and Sporothrix strains. However, all compounds showed no activity at the tested concentrations.

Structure-based discovery of thiosemicarbazones as SARS-CoV-2 main protease inhibitors

Aim: Discovery of novel SARS-CoV-2 main protease (Mpro) inhibitors using a structure-based drug discovery strategy. Materials & methods: Virtual screening employing covalent and noncovalent docking was performed to discover Mpro inhibitors, which were subsequently evaluated in biochemical and cellular assays. Results: 91 virtual hits were selected for biochemical assays, and four were confirmed as reversible inhibitors of SARS CoV-2 Mpro with IC50 values of 0.4-3 μM. They were also shown to inhibit SARS-CoV-1 Mpro and human cathepsin L. Molecular dynamics simulations indicated the stability of the Mpro inhibitor complexes and the interaction of ligands at the subsites. Conclusion: This approach led to the discovery of novel thiosemicarbazones as potent SARS-CoV-2 Mpro inhibitors.

Abdellattif. Indenyl-thiazole and indenyl-formazan derivatives: Synthesis, anticancer screening studies, molecular-docking, and pharmacokinetic/ molin-spiration properties

Two new series of thiazole and formazan linked to 5-Bromo-indan were synthesized, and their structures were assured based on all possible analytical techniques. The size of the tested derivatives was calculated from the XRD technique and found five derivatives 3, 10a, 14a, 15, and 16 on the nanosized scale. The two series were tested for their efficacy and toxicity as anti-colon and stomach cancers. Derivative 10d showed activity more than the two reference drugs used in the case of SNU-16. Surpislly, in the case of COLO205, five derivatives 4, 6c, 6d, 6e, and 10a are better than the two benchmarks used, and two derivatives, 14a and 14b more potent than cisplatin. All potent derivatives showed a strong fit with the active site of the two tested proteins (gastric cancer (PDB = 2BID) and colon cancer (PDB = 2A4L)) in the molecular docking study. The Pharmacophore and ADME studies of the new derivatives showed that most derivatives revealed promising bioactivity, which indicates the drug-likeness properties against kinase inhibitors, protease, and enzyme inhibitors. In addition, the ProTox-II showed that the four compounds 10d, 16, 6d, and 10a are predicted to have oral LD50 values ranging from 335 to 3500 mg/kg in a rat model with (1 s,4 s)-Eucalyptol bearing the highest values and quercetin holding the lowest one.

4-[Bis(thiazol-2-ylamino)methyl]phenol

We have designed and synthesized novel bis-thiazole derivative. A 4-[bis(thiazol-2-ylamino)methyl]phenol was efficiently prepared in 71% yield by the reaction of 2-aminothiazole with 4-hydroxybenzaldehyde in ethanol for 24 h. The structure of newly obtained compound was characterized by 1H, 13C NMR and mass spectrometry. Bis-thiazole derivative exhibits high tyrosinase inhibitory activity with an IC50 value of 29.71 μM. This inhibitory activity is 2.4 times higher than that of activity of kojic acid (IC50 72.27 µM) and almost 13 times higher than that of ascorbic acid (IC50 385.6 µM). Obtained data suggest that the presented compound may be a leading candidate for a tyrosinase inhibitor.

Spectrofluorimetric and Computational Investigation of New Phthalimide Derivatives towards Human Neutrophil Elastase Inhibition and Antiproliferative Activity

Herein, nine phthalimide-based thiazoles (4a-4i) were synthesized and investigated as new human neutrophil elastase (HNE) inhibitors using spectrofluorimetric and computational methods. The most active compounds containing 4-trifluoromethyl (4c), 4-naphthyl (4e) and 2,4,6-trichloro (4h) substituents in the phenyl ring exhibited high HNE inhibitory activity with IC₅₀ values of 12.98-16.62 µM. Additionally, compound 4c exhibited mixed mechanism of action. Computational investigation provided a consistent picture of the ligand-receptor pattern of inter-actions, common for the whole considered group of compounds. Moreover, compounds 4b, 4c, 4d and 4f showed high antiproliferative activity against human cancer cells lines MV4-11, and A549 with IC₅₀ values of 8.21 to 25.57 µM. Additionally, compound 4g showed high activity against MDA-MB-231 and UMUC-3 with IC₅₀ values of 9.66 and 19.81 µM, respectively. Spectrophotometric analysis showed that the most active compound 4c demonstrated high stability under physiological conditions.

Quantitative structure-activity relationship and machine learning studies of 2-thiazolylhydrazone derivatives with anti-Cryptococcus neoformans activity

Cryptococcus neoformans is a fungus responsible for infections in humans with a significant number of cases in immunosuppressed patients, mainly in underdeveloped countries. In this context, the thiazolylhydrazones are a promising class of compounds with activity against C. neoformans. The understanding of the structure-activity relationship of these derivatives could lead to the design of robust compounds that could be promising drug candidates for fungal infections. Specifically, modern techniques such as 4D-QSAR and machine learning methods were employed in this work to generate two QSAR models (one 2D and one 4D) with high predictive power (r² for the test set equals to 0.934 and 0.831, respectively), and one random forest classification model was reported with Matthews correlation coefficient equals to 1 and 0.62 for internal and external validations, respectively. The physicochemical interpretation of selected models, indicated the importance of aliphatic substituents at the hydrazone moiety to antifungal activity, corroborating experimental data.Communicated by Ramaswamy H. Sarma.

The Anti-MRSA Activity of Phenylthiazoles: A Comprehensive Review

Antimicrobial resistance is an aggravating global issue therefore it has been under extensive research in an attempt to reduce the number of antibiotics that are constantly reported as obsolete jeopardizing the lives of millions worldwide. Thiazoles possess a reputation as one of the most diverse biologically active nuclei, and phenylthiazoles are no less exceptional with an assorted array of biological activities such as anthelmintic, insecticidal, antimicrobial, antibacterial, and antifungal activity. Recently phenyl thiazoles came under the spotlight as a scaffold having strong potential as an anti-MRSA lead compound. It is a prominent pharmacophore in designing and synthesizing new compounds with antibacterial activity against multidrug-resistant bacteria such as MRSA, which is categorized as a serious threat pathogen, that exhibited concomitant resistance to most of the first-line antibiotics. MRSA has been associated with soft tissue and skin infections resulting in high death rates, rapid dissemination, and loss of millions of dollars of additional health care costs. In this brief review, we have focused on the advances of phenylthiazole derivatives as potential anti-MRSA from 2014 to 2021. The review encompasses the effect on biological activity due to combining this molecule with various synthetic pharmacophores. The physicochemical aspects were correlated with the pharmacokinetic properties of the reviewed compounds to reach a structure-activity relationship profile. Lead optimization of phenyl thiazole derivatives has additionally been outlined where the lipophilicity of the compounds was balanced with the metabolic stability and oral solubility to aid the researchers in medicinal chemistry, design, and synthesizing effective anti- MRSA phenylthiazoles in the future.

Multicomponent synthesis of fully substituted thiazoles using glycine-based dithiocarbamates, acetic anhydride and nitroalkenes

Reaction of glycine-based dithiocarbamates with nitroalkenes in the presence of acetic anhydride was utilized for the synthesis of fully substituted 2-(alkylsulfanyl)-4-(nitroalkyl)-5-acyloxy-1,3-thiazoles. The reaction proceeds via the in situ formation of thiazol-5(4H)-one from glycine-based dithiocarbamates, followed by the Michael addition of this intermediate to nitroalkenes, aromatization, and esterification reaction cascade. This new one-pot three-component reaction afforded a diverse library of fully substituted thiazoles in high to excellent yields under solvent-free conditions.

SAR analysis of heterocyclic compounds with monocyclic and bicyclic structures as antifungal agents

Infections caused by eukaryotic organisms, such as fungi, are generally more difficult to treat than bacterial infections. With the widespread use of antifungal drugs in humans and plants, resistance and toxicity have emerged. Therefore, it is desirable to develop new antifungal drugs with low toxicity that are not susceptible to the development of resistance. This review presents a summary of the past 2017 to 2021 years of research on heterocyclic compounds as antifungal agents for use in humans and plants, focusing on the structure-activity relationships (SAR) of these compounds. This review may provide ideas and data for designing and developing new antifungal drugs with fewer side effects compared with currently available drugs.

Thiazole and Related Heterocyclic Systems as Anticancer Agents: A Review on Synthetic Strategies, Mechanisms of Action and SAR Studies

Background:

Cancer is the second leading cause of death throughout the world. Many anticancer drugs are commercially available, but lack of selectivity, target specificity, cytotoxicity and development of resistance lead to serious side effects. There have been several experiments going on to develop compounds with minor or no side effects.

Objective:

This review mainly emphasizes synthetic strategies, SAR studies, and mechanism of action for thiazole, benzothiazole, and imidazothiazole containing compounds as anticancer agents.

Methods:

Recent literature related to thiazole and thiazole-related derivatives endowed with encouraging anticancer potential is reviewed. This review emphasizes contemporary strategies used for the synthesis of thiazole and related derivatives, mechanistic targets, and comprehensive structural activity relationship studies to provide perspective into the rational design of high-efficiency thiazole-based anticancer drug candidates.

Results:

Exhaustive literature survey indicated that thiazole derivatives are associated with properties of inducing apoptosis and disturbing tubulin assembly. Thiazoles are also associated with the inhibition of NFkB/mTOR/PI3K/AkT and regulation of estrogen-mediated activity. Furthermore, thiazole derivatives have been found to modulate critical targets such as topoisomerase and HDAC.

Conclusion:

Thiazole derivatives seem to be quite competent and act through various mechanisms. Some of the thiazole derivatives, such as compounds 29, 40, 62, and 74a with IC50 values of 0.05 μM, 0.00042 μM, 0.18 μM, and 0.67 μM, respectively not only have anticancer activity but they also have lower toxicity and better absorption. Therefore, some other similar compounds could be investigated to aid in the development of anticancer pharmacophores.

Synthesis, electrochemical, optical and biological properties of new carbazole derivatives

Carbazole skeleton is the key structural motif of many biologically active compounds including synthetic and natural products. Based on the (E)-2-(2-(4-9H-carbazol-9-yl)benzylidene) hydrazinyl)thiazole as skeleton, three novel carbazole dyes were synthesized. The scientific analysis includes the effect of changing the strength of the activating substituents and their exchange for the deactivating substituent on the chemical and biological properties. The presented research showed a significant influence of the CH₃, OCH₃ and CH₂COOC₂H₅ groups on the spectral properties of the tested derivatives. Their significant influence is also visible in electrochemical, nonlinear-optic and biological properties. The study also included the analysis of the use of the presented derivatives as potential fluorescent probes for in vivo and in vitro tests. Quantum-chemical calculations complement the conducted experiments.

The Brazilian compound library (BraCoLi) database: a repository of chemical and biological information for drug design

The Brazilian Compound Library (BraCoLi) is a novel open access and manually curated electronic library of compounds developed by Brazilian research groups to support further computer-aided drug design works, available on https://www.farmacia.ufmg.br/qf/downloads/ . Herein, the first version of the database is described comprising 1176 compounds. Also, the chemical diversity and drug-like profiles of BraCoLi were defined to analyze its chemical space. A significant amount of the compounds fitted Lipinski and Veber's rules, alongside other drug-likeness properties. A comparison using principal component analysis showed that BraCoLi is similar to other databases (FDA-approved drugs and NuBBE_DB) regarding structural and physicochemical patterns. Furthermore, a scaffold analysis showed that BraCoLi presents several privileged chemical skeletons with great diversity. Despite the similar distribution in the structural and physicochemical spaces, Tanimoto coefficient values indicated that compounds present in the BraCoLi are generally different from the two other databases, where they showed different kernel distributions and low similarity. These facts show an interesting innovative aspect, which is a desirable feature for novel drug design purposes.

Current Status and Structure Activity Relationship of Privileged Azoles as Antifungal Agents (2016-2020)

Fungal infections have major contribution to the infectious related deaths in recent century. The issue has gotten worse with the advent of immunity impairing conditions such as HIV epidemic. Eukaryote nature of fungal pathogens leads to harder eradication than bacterial infections. Given the importance of the problem, considerable efforts have been put on the synthesis and biological assessment of azole-based chemical scaffolds and their bioisosteres. The emergence of validated macromolecular targets within different fungal species inspires structure-based drug design strategies toward diverse azole-based agents. Despite of advantageous features, emergence of drug-resistant fungal species restrict the applicability of current azoles as the first-line antifungal agents. Consequently, it appears advisable to elucidate SARs and chemical biodiversity within antifungal azoles. Current contribution was devoted to a brief look at clinically applied drugs, structure-based classification of azole antifungals and their structure activity relationships (SARs). Reviewed molecules belong to the antifungal structures that were reported throughout 2016-2020.

Synthesis, DFT Analysis, and Evaluation of Antibacterial and Antioxidant Activities of Sulfathiazole Derivatives Combined with In Silico Molecular Docking and ADMET Predictions

Synthetic modifications of sulfathiazole derivatives become an interesting approach to enhance their biological properties in line with their applications. As a result, sulfathiazole derivatives become a good candidate and potential class of organic compounds to play an important role towards medicinal chemistry. In present study, one thiazole derivative and two new sulfathiazole derivatives are synthesized with 94% and 72–81% yields, respectively. Furthermore, the synthesized compounds were evaluated for their in vitro antibacterial activity against two Gram-negative (E. coli and P. aeruginosa) and two Gram-positive bacterial strains (S. pyogenes and S. aureus) by disk diffusion method. Among synthesized compounds, compound 11a showed potent inhibitory activity against Gram-negative, E. coli with 11.6 ± 0.283 mm zone of inhibition compared to standard drug sulfamethoxazole (15.7 ± 0.707 mm) at 50 mg/mL. The radical scavenging activities of these compounds were evaluated using DPPH radical assay, and compound 11a showed the strongest activity with IC₅₀ values of 1.655 μg/mL. The synthesized compounds were evaluated for their in silico molecular docking analysis using S. aureus gyrase (PDB ID: 2XCT) and human myeloperoxidase (PDB ID: 1DNU) and were found to have minimum binding energy ranging from −7.8 to −10.0 kcal/mol with 2XCT and −7.5 to −9.7 with 1DNU. Compound 11a showed very good binding score −9.7 kcal/mol with both of the proteins and had promising alignment with in vitro results. Compound 11b also showed high binding scores with both proteins. Drug likeness and ADMET of synthesized compounds were predicted. The DFT analysis of synthesized compounds was performed using Gaussian 09 and visualized through Gauss view 6.0. The structural coordinates of the lead compounds were optimized using B3LYP/6–31 G (d,p) level basis set without any symmetrical constraints. Studies revealed that all the synthesized compounds might be candidates for further antibacterial and antioxidant studies.

Design, Synthesis and Molecular Modeling of Quinoline Based Derivatives as Anti-Breast Cancer Agents Targeting EGFR/AKT Signaling Pathway

Two series of quinoline-thiazole and quinoline-thiazolidinone hybrids were designed, synthesized and evaluated for their in vitro antitumor activity on MCF-7 breast cancer cell line. In comparison to lapatinib (IC₅₀ =4.69 µM), compounds 4b and 6b exhibited the best antiproliferative activity with IC₅₀ values of 33.19 and 5.35 µM, respectively. Although compound 6b showed higher cytotoxicity, compound 4b exhibited better inhibitory activity towards the EGFR pathway than compound 6b as represented by the significant reduction in the EGFR kinase activity and the levels of phosho-EGFR and phosho-AKT when compared to lapatinib as a reference standard. Moreover, compound 4b was capable of down-regulating the anti-apoptotic genes Bcl-2 and survivin and up-regulating the level of the pro-apoptotic gene BAX. Molecular modeling study was carried out to predict the binding interactions of both compounds into the target kinase. Finally, the physicochemical properties were investigated in silico as well.

Novel Citral-thiazolyl Hydrazine Derivatives as Promising Antifungal Agents against Phytopathogenic Fungi

To develop new antifungal agents against phytopathogenic fungi, a series of citral-thiazolyl hydrazine derivatives were designed, synthesized, and characterized by FT-IR, ¹H NMR, ¹³C NMR, and HRMS. Antifungal activity results showed that most synthetic compounds exhibited broad-spectrum antifungal activities against six phytopathogenic fungi in vitro. Notably, compounds b and c15 exhibited remarkable antifungal activity against Colletotrichum gloeosprioides, Rhizoctonia solani, Phytophthora nicotianae var. nicotianae, Diplodia pinea, Colletotrichum acutatum, and Fusarium oxysporum f. sp. niveum, which were all superior to the positive control tricyclazole. Structure-activity relationship (SAR) studies demonstrated that introducing electron-withdrawing groups such as F on the benzene ring exhibited outstanding antifungal activities against all the tested fungi. Furthermore, compound b could effectively control rice sheath blight and showed higher curative activities against R. solani than validamycin·bacillus in vivo. In addition, the in vitro cytotoxicity results indicated that compound b possessed moderate cytotoxicity activity, and all citral-thiazolyl hydrazine derivatives exhibited lower or no cytotoxicity to the LO2 and HEK293 cell lines. In addition, the acute oral toxicity test showed that compound b had moderate toxicity (level II) with an LD₅₀ value of 310 mg/kg bw (95% confidence limit: 175-550 mg/kg bw). Finally, a preliminary action mechanism study showed that causing obvious malformation of mycelium and increasing cell membrane permeability are two of the potential mechanisms by which compound b exerts antifungal activity. The present work indicates that some of these derivatives may serve as novel potential fungicides, and compound b is expected to be the leading structure for the development of new antifungal agents.

Molecular insights on ABL kinase activation using tree-based machine learning models and molecular docking

Abelson kinase (c-Abl) is a non-receptor tyrosine kinase involved in several biological processes essential for cell differentiation, migration, proliferation, and survival. This enzyme's activation might be an alternative strategy for treating diseases such as neutropenia induced by chemotherapy, prostate, and breast cancer. Recently, a series of compounds that promote the activation of c-Abl has been identified, opening a promising ground for c-Abl drug development. Structure-based drug design (SBDD) and ligand-based drug design (LBDD) methodologies have significantly impacted recent drug development initiatives. Here, we combined SBDD and LBDD approaches to characterize critical chemical properties and interactions of identified c-Abl's activators. We used molecular docking simulations combined with tree-based machine learning models-decision tree, AdaBoost, and random forest to understand the c-Abl activators' structural features required for binding to myristoyl pocket, and consequently, to promote enzyme and cellular activation. We obtained predictive and robust models with Matthews correlation coefficient values higher than 0.4 for all endpoints and identified characteristics that led to constructing a structure-activity relationship model (SAR).

Synthesis and Physicochemical Characterization of Novel Dicyclopropyl-Thiazole Compounds as Nontoxic and Promising Antifungals

There is a need to search for new antifungals, especially for the treatment of the invasive Candida infections, caused mainly by C. albicans. These infections are steadily increasing at an alarming rate, mostly among immunocompromised patients. The newly synthesized compounds (3a-3k) were characterized by physicochemical parameters and investigated for antimicrobial activity using the microdilution broth method to estimate minimal inhibitory concentration (MIC). Additionally, their antibiofilm activity and mode of action together with the effect on the membrane permeability in C. albicans were investigated. Biofilm biomass and its metabolic activity were quantitatively measured using crystal violet (CV) staining and tetrazolium salt (XTT) reduction assay. The cytotoxic effect on normal human lung fibroblasts and haemolytic effect were also evaluated. The results showed differential activity of the compounds against yeasts (MIC = 0.24-500 µg/mL) and bacteria (MIC = 125-1000 µg/mL). Most compounds possessed strong antifungal activity (MIC = 0.24-7.81 µg/mL). The compounds 3b, 3c and 3e, showed no inhibitory (at 1/2 × MIC) and eradication (at 8 × MIC) effect on C. albicans biofilm. Only slight decrease in the biofilm metabolic activity was observed for compound 3b. Moreover, the studied compounds increased the permeability of the membrane/cell wall of C. albicans and their mode of action may be related to action within the fungal cell wall structure and/or within the cell membrane. It is worth noting that the compounds had no cytotoxicity effect on pulmonary fibroblasts and erythrocytes at concentrations showing anticandidal activity. The present studies in vitro confirm that these derivatives appear to be a very promising group of antifungals for further preclinical studies.

Effect of the Chloro-Substitution on Electrochemical and Optical Properties of New Carbazole Dyes

Carbazole derivatives are the structural key of many biologically active substances, including naturally occurring and synthetic ones. Three novel (E)-2-(2-(4-9H-carbazol-9-yl)benzylidene)hydrazinyl)triazole dyes were synthesized with different numbers of chlorine substituents attached at different locations. The presented research has shown the influence of the number and position of attachment of chlorine substituents on electrochemical, optical, nonlinear, and biological properties. The study also included the analysis of the use of the presented derivatives as potential fluorescent probes for in vivo and in vitro tests. Quantum-chemical calculations complement the conducted experiments.

Thiazole Ring-A Biologically Active Scaffold

BACKGROUND

Thiazole is a good pharmacophore nucleus due to its various pharmaceutical applications. Its derivatives have a wide range of biological activities such as antioxidant, analgesic, and antimicrobial including antibacterial, antifungal, antimalarial, anticancer, antiallergic, antihypertensive, anti-inflammatory, and antipsychotic. Indeed, the thiazole scaffold is contained in more than 18 FDA-approved drugs as well as in numerous experimental drugs.

OBJECTIVE

To summarize recent literature on the biological activities of thiazole ring-containing compounds Methods: A literature survey regarding the topics from the year 2015 up to now was carried out. Older publications were not included, since they were previously analyzed in available peer reviews.

RESULTS

Nearly 124 research articles were found, critically analyzed, and arranged regarding the synthesis and biological activities of thiazoles derivatives in the last 5 years.

Facile One-Pot Multicomponent Synthesis of Pyrazolo-Thiazole Substituted Pyridines with Potential Anti-Proliferative Activity: Synthesis, In Vitro and In Silico Studies

Pyrazolothiazole-substituted pyridine conjugates are an important class of heterocyclic compounds with an extensive variety of potential applications in the medicinal and pharmacological arenas. Therefore, herein, we describe an efficient and facile approach for the synthesis of novel pyrazolo-thiazolo-pyridine conjugate 4, via multicomponent condensation. The latter compound was utilized as a base for the synthesis of two series of 15 novel pyrazolothiazole-based pyridine conjugates (5-16). The newly synthesized compounds were fully characterized using several spectroscopic methods (IR, NMR and MS) and elemental analyses. The anti-proliferative impact of the new synthesized compounds 5-13 and 16 was in vitro appraised towards three human cancer cell lines: human cervix (HeLa), human lung (NCI-H460) and human prostate (PC-3). Our outcomes regarding the anti-proliferative activities disclosed that all the tested compounds exhibited cytotoxic potential towards all the tested cell lines with IC₅₀ = 17.50-61.05 µM, especially the naphthyridine derivative 7, which exhibited the most cytotoxic potential towards the tested cell lines (IC₅₀ = 14.62-17.50 µM) compared with the etoposide (IC50 = 13.34-17.15 µM). Moreover, an in silico docking simulation study was performed on the newly prepared compounds within topoisomerase II (3QX3), to suggest the binding mode of these compounds as anticancer candidates. The in silico docking results indicate that compound 7 was a promising lead anticancer compound which possesses high binding affinity toward topoisomerase II (3QX3) protein.

Design, synthesis and docking studies of novel thiazole derivatives incorporating pyridine moiety and assessment as antimicrobial agents

A novel series of substituted 4,6-dimethyl-2-oxo-1-(thiazol-2-ylamino)-1,2-dihydropyridine-3-carbonitrile derivatives 6, 9, 13, 15, and 17 was synthesized in a good to excellent yield from the reaction of 1-(3-cyano-4,6-dimethyl-2-oxopyridin-1(2H)-yl)thiourea with 2-oxo-N'-arylpropanehydrazonoyl chloride, chloroacetone, α-bromoketones, ethyl chloroacetate, and 2,3-dichloroquinoxaline, respectively. The potential DNA gyrase inhibitory activity was examined using in silico molecular docking simulation. The novel thiazoles exhibit dock score values between - 6.4 and - 9.2 kcal/mol and they were screened for their antimicrobial activities. Compound 13a shown good antibacterial activities with MIC ranged from 93.7-46.9 μg/mL, in addition, it shown good antifungal activities with MIC ranged from 7.8 and 5.8 μg/mL.

Mechanisms of Candida Resistance to Antimycotics and Promising Ways to Overcome It: The Role of Probiotics

Pathogenic Candida and infections caused by those species are now considered as a serious threat to public health. The treatment of candidiasis is significantly complicated by the increasing resistance of pathogenic strains to current treatments and the stagnant development of new antimycotic drugs. Many species, such as Candida auris, have a wide range of resistance mechanisms. Among the currently used synthetic and semi-synthetic antifungal drugs, the most effective are azoles, echinocandins, polyenes, nucleotide analogs, and their combinations. However, the use of probiotic microorganisms and/or the compounds they produce is quite promising, although underestimated by modern pharmacology, to control the spread of pathogenic Candida species.

Novel structural hybrids of quinoline and thiazole moieties: Synthesis and evaluation of antibacterial and antifungal activities with molecular modeling studies

One of the best ways to design new biocidal agents is synthesizing hybrid molecules by combining two or more bioactive moieties in a single molecular scaffold. So, new series of quinolines bearing a thiazole moiety were synthesized using thiosemicarbazones 2a-f. Cyclization of 2a-f with ethyl chloroacetate, ethyl 2-chloropropanoate or chloroacetone afforded the corresponding thiazoles 3-5. The antimicrobial activity of the new quinoline derivatives was evaluated. The most of tested compounds revealed potent both of the antibacterial and antifungal activities. Fourfold potency of amphotericin B for the inhibition the growth of the A. fumigatus was displayed by ccompound 5e. The latter compound displayed twofold potency of gentamycin for inhibition the growth of N. gonorrhoeae. Moreover, this compound showed equipotent potency of references drugs for inhibition of the growth of S. flexneri, S. pyogenes, P. vulgaris, A. clavatus, G. candidum and P. marneffei. So, quinolines bearing a thiazole moiety can be suggested as interesting scaffolds for the development both of the novel antibacterial and antifungal agents. Some new derivatives were studied as peptide deformylase enzyme inhibitors. Thiazolidin-4-one derivative 3d and 2,3-dihydrothiazole derivative 5c had shown good PDF inhibition activity, which had been supported by the docking results with highest binding affinity and lowest docking energy score. These results suggested that the most potent compounds might be possible agents as novel bacterial PDF inhibitor.