Exploring the Recent Pioneering Developments of Small Molecules in Antimalarial Drug Armamentarium: A Chemistry Prospective Appraisal

Malaria is a very destructive and lethal parasitic disease that causes significant mortality worldwide, resulting in the loss of millions of lives annually. It is an infectious disease transmitted by mosquitoes, which is caused by different species of the parasite protozoan belonging to the genus Plasmodium. The uncontrolled intake of antimalarial drugs often employed in clinical settings has resulted in the emergence of numerous strains of plasmodium that are resistant to these drugs, including multidrug-resistant strains. This resistance significantly diminishes the effectiveness of many primary drugs used in the treatment of malaria. Hence, there is an urgent need for developing unique classes of antimalarial drugs that function with distinct mechanisms of action. In this context, the design and development of hybrid compounds that combine pharmacophoric properties from different lead molecules into a single unit gives a unique perspective towards further development of malaria drugs in the next generation. In recent years, the field of medicinal chemistry has made significant efforts resulting in the discovery and synthesis of numerous small novel compounds that exhibit potent antimalarial properties, while also demonstrating reduced toxicity and desirable efficacy. In light of this, we have reviewed the progress of hybrid antimalarial agents from 2021 up to the present. This manuscript presents a comprehensive overview of the latest advancements in the medicinal chemistry pertaining to small molecules, with a specific focus on their potential as antimalarial agents. As possible antimalarial drugs that might target both the dual stage and multi-stage stages of the parasite life cycle, these small hybrid molecules have been studied. This review explores a variety of physiologically active compounds that have been described in the literature in order to lay a strong foundation for the logical design and eventual identification of antimalarial drugs based on lead frameworks.

Converging optical and electrochemical detection strategies for multimodal hydrazine sensing: insights into substituent-driven diverse response

A pair of pyrene-based chalcogen derivatives have been developed, which demonstrate multimodal ratiometric response towards hydrazine. Although these probes share a common pyrene core and differ primarily in the electronic nature of their terminal side arms, they display distinct photophysical properties. Notably, both probes undergo significant spectral changes upon the addition of hydrazine, but probe 1 exhibits a more pronounced interaction (∼5-fold fluorescence enhancement) than probe 2, attributed to the higher level of aggregation in probe 2, rendering the binding site less accessible to the incoming analyte. Additionally, we have explored electrochemical techniques, including cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), for hydrazine detection. Our molecular design strategy relies on ratiometric-responsive specific cyclization triggered by hydrazine, leading to the disruption of the π-conjugated system and the subsequent suppression of intramolecular charge transfer (ICT) processes, along with dis-assembly of the aggregated probe molecules. These probes enable the nakеd-eye detection of hydrazine, with a low detection limit of 7.33 ppb and 7.58 ppb for probe 1 and 2, respectively. Furthermore, we have investigated cost-effective probe-coatеd paper strips for the detection of hydrazine in water.

Development of benzaldehyde-pyrazoline hybrids for functionalization of polymers with fluorescent pendant moieties

Compounds with a pyrazoline scaffold are useful as sensors for fluorescence detection of different types of analytes. Recovery of a pyrazoline-based sensor with a view to use it recurrently would be more facile when the sensing molecule is attached to a solid support. A reaction sequence has been designed to synthesize two benzaldehyde-pyrazoline hybrids as examples of a hitherto unknown type of compounds to be employed for the potential derivatization of polymers containing primary amino groups through azomethine formation. All intermediates, including the fairly unstable N1 -unsubstituted pyrazolines, along with the target compounds have been structurally characterized, with an emphasis on their particular NMR features. Examination of the photophysical properties of these benzaldehyde-pyrazoline hybrids showed that, despite the shortening of the extended N1-N2-C3 conjugated system common to 1,3,5-triarylpyrazolines through the replacement of the aryl at N1 by an aryloxyacetyl moiety, the novel compounds exhibit emission maxima at approximately 350 nm. Moreover, the introduction of a moderately electron-withdrawing substituent such as chlorine in the phenyl at C3 of pyrazoline leads to an amplification of fluorescence intensity.

Novel pyrazoline and pyrazole "turn on" fluorescent sensors selective for Zn2+/Cd2+ at λem 480 nm and Fe3+/Fe2+ at λem 465 nm in MeCN

A small series of simple pyrazoline and pyrazole based sensors, all derived from the same chalcone precursors, were synthesised, characterised and screened for their fluorescence "turn on" properties in the presence of multiple metals. Pyrazole 8 displayed an excellent fluorescence profile with approx. 20× fold increase in λem 480 nm with Zn2+ compared to a 2.5× fold increase with Cd2+. Pyrazole 9 displayed a 30× fold increase at λem 465 nm for Fe3+ compared to Fe2+ with a Fe3+ limit of detection of 0.025 μM. The corresponding pyrazolines displayed contrasting properties with important implications for future pyrazoline and pyrazole sensor design.

Novel pyrazoline linked acyl thiourea pharmacophores as antimicrobial, urease, amylase and α-glucosidase inhibitors: design, synthesis, SAR and molecular docking studies

In the present work, a small library of novel pyrazolinyl-acyl thiourea (5a-j) was designed and synthesized through a multistep sequence and the synthesized compounds were screened for their antifungal, antibacterial and antioxidant activities as well as urease, amylase and α-glucosidase inhibitory activities. The synthesized series (5a-o) was characterized using a combination of spectroscopic techniques, including FT-IR, 1H NMR and 13C NMR. All compounds (5a-j) were found to have significant potency against urease, α-glucosidase, α-amylase, and DPPH. The synthesized compounds were also screened for potential antibacterial and anti-fungal inhibition activities. IC50 values for all the prepared compounds for urease, α-glucosidase, amylase, and DPPH inhibition were determined and derivatives 5b and 5g were found to be the most potent urease inhibitors with IC50 values of 54.2 ± 0.32 and 43.6 ± 0.25 μM, respectively. Whilst compound 5b (IC50 = 68.3 ± 0.11 μM) is a potent α-glucosidase inhibitor, compound 5f (90.3 ± 1.08 μM) is a potent amylase inhibitor and compound 5b (103.4 ± 1.15 μM) is a potent antioxidant. The different substitutions on the phenyl ring were the basis for structure-activity relationship (SAR) study. The molecular docking study was performed for the confirmation of binding interactions.

Tandem Addition/Cyclization/Halogenation Reaction of Difluoromethylated N-Acylhydrazones with Allyltrimethylsilanes

As novel difluoromethyl building blocks, difluoromethylated N-acylhydrazones react with allyltrimethylsilanes and the halogen source via a tandem addition/cyclization/halogenation strategy, which produces various difluoromethylpyrazoline compounds in good yields. The method features mild reaction conditions, broad substrate scopes, and a transition metal-free process with easy operation. It also proves that difluoromethylated N-acylhydrazones are useful difluoromethyl building blocks for the construction of difluoromethylated nitrogen heterocycles.

The Synthesis, In Vitro Bio-Evaluation, and In Silico Molecular Docking Studies of Pyrazoline-Thiazole Hybrid Analogues as Promising Anti-α-Glucosidase and Anti-Urease Agents

In the present work, a concise library of benzothiazole-derived pyrazoline-based thiazole (1-17) was designed and synthesized by employing a multistep reaction strategy. The newly synthesized compounds were screened for their α-glucosidase and urease inhibitory activities. The scaffolds (1-17) were characterized using a combination of several spectroscopic techniques, including FT-IR, 1H-NMR, 13C-NMR, and EI-MS. The majority of the synthesized compounds demonstrated a notable potency against α-glucosidase and urease enzymes. These analogues disclosed varying degrees of α-glucosidase and urease inhibitory activities, with their IC50 values ranging from 2.50 to 17.50 μM (α-glucosidase) and 14.30 to 41.50 (urease). Compounds 6, 7, 14, and 12, with IC50 values of 2.50, 3.20, 3.40, and 3.50 μM as compared to standard acarbose (IC50 = 5.30 µM), while the same compounds showed 14.30, 19.20, 21.80, and 22.30 comparable with thiourea (IC50 = 31.40 μM), respectively, showed excellent inhibitory activity. The structure-activity relationship revealed that the size and electron-donating or electron-withdrawing effects of substituents influenced the enzymatic activities such as α-glucosidase and urease. Compound 6 was a dual potent inhibitor against α-glucosidase and urease due to the presence of -CF3 electron-withdrawing functionality on the phenyl ring. To the best of our knowledge, these synthetic compounds were found to be the most potent dual inhibitors of α-glucosidase and urease with minimum IC50 values. Moreover, in silico studies on most active compounds, i.e., 6, 7, 14, and 12, were also performed to understand the binding interaction of most active compounds with active sites of α-glucosidase and urease enzymes.

Acetic Acid-Catalyzed (3 + 2) Cyclization of 2-Aroyl-3-aryl-1,1-dicyanocyclopropanes with Arylhydrazines: To trans-4-Dicyanomethyl-1,3,5-triaryl-4,5-dihydropyrazoles

Acetic acid-catalyzed (3 + 2) cyclization reaction of substituted 2-aroyl-3-aryl-1,1-dicyanocyclopropanes with arylhydrazines was investigated for the efficient synthesis of 4-dicyanomethyl-1,3,5-triaryl-4,5-dihydropyrazoles in good yields, in which 4,5-double substituents are predominantly trans selective. This approach included the consecutive condensation, ring opening, and double nucleophilic cyclization reaction.

Construction of Highly Functionalized C4-Oxyacylated and Aminated Pyrazolines

Pyrazolines and pyrazolones are prevalent cores in drugs and bioactive molecules. Functionalizing them with heteroatoms on the ring improves or expands their clinical efficacy. However, a general method to selectively heterofunctionalize them at C4 and C5 is still elusive. Herein, we have demonstrated an iodine(III)-mediated construction of C4-heterofunctionalized pyrazolines from α,β-unsaturated hydrazones. The oxyacylated and aminated products, bearing a tertiary as well as a secondary stereocenter, were obtained via aza-Michael, followed by a C-O/C-N bond formation. A deprotection/oxidation sequence produced pyrazolones in a quantitative yield.

Double Bond Geometric Isomers of Pentaketide Ansamycins from Streptomyces sp. S008

Six new pentaketide ansamycins, namely, shengliangmycins A-F (1-6, respectively), were obtained from the fermentation products of Streptomyces sp. S008OEslmR2 that was derived by constitutive expression of LAL regulator gene slmR2. The structures of 1-6 were determined through comprehensive spectroscopic analysis and single-crystal X-ray diffraction. Compound 1 has a cis-C6═C7 bond, which is different from that of compounds 2-5. Compounds 3-6 feature a morpholinone structural moiety, whereas 5 is characterized by a pyrazoline ring, which is rare in natural products.

Assessing the effect of N-oxidation on the mutagenicity of 1-pyrazolines using the Ames assay

N-Nitrosamines are well known as environmental carcinogens. We have reported that N-nitroso-N-methylbutylamine was oxidized by Fe2+-Cu2+-H2O2 to 5-methyl-5-nitro-1-pyrazoline, a direct-acting N-oxide. 1-Pyrazolines have not been reported to exhibit genotoxicity. In this study, we investigated the effect of N-oxidation on the mutagenicity of 1-pyrazolines using the Ames assay. The mutagenicity of 5-alkyl-5-nitro-1-pyrazoline 1-oxide (1a; methyl, 1b; ethyl), the N-oxide isomer (3-alkyl-3-nitro-1-pyrazoline 1-oxide; 2a; methyl, 2b; ethyl), and the corresponding nonoxides (3-alkyl-3-nitro-1-pyrazoline; 3a; methyl, 3b; ethyl) was assayed in Salmonella typhimurium TA1535 and Escherichia coli WP2uvrA. The ratios of mutagenic potency in S. typhimurium TA1535 versus E. coli WP2uvrA were compared with those of N-alkylnitrosoureas. To predict the reaction site on the pyrazolines with nucleophiles, the electron density of the pyrazolines was obtained by theoretical calculations. The pyrazolines were mutagenic in S. typhimurium TA1535 and E. coli WP2uvrA. The ratio of S. typhimurium TA1535 to E. coli WP2uvrA 1a (87:13) or 1b (90:10) was similar to that of N-ethyl-N-nitrosourea (70:30). In contrast, the mutagenic ratio of 2a (22:78) or 2b (52:48) was similar to that of N-propyl-N-nitrosourea (48:52) or N-butyl-N-nitrosourea (14:86). The ratio of 3a (53:47) or 3b (54:46) was similar to that of N-propyl-N-nitrosourea or N-butyl-N-nitrosourea. The pyrazolines exhibit genotoxicity, and the mutagenic potency of the 1-pyrazolines is influenced by N-oxidation. We estimated that the mutagenicity of 1a or 1b was caused by DNA ethylation, and the isomers or the nonoxides were mutagenic via formation of alkylated DNA, which contains an alkyl chain longer than the propyl.

N-, O- and S-Heterocycles Synthesis in Deep Eutectic Solvents

The synthesis of heterocycles is a fundamental area of organic chemistry that offers enormous potential for the discovery of new products with important applications in our daily life such as pharmaceuticals, agrochemicals, flavors, dyes, and, more generally, engineered materials with innovative properties. As heterocyclic compounds find application across multiple industries and are prepared in very large quantities, the development of sustainable approaches for their synthesis has become a crucial objective for contemporary green chemistry committed to reducing the environmental impact of chemical processes. In this context, the present review focuses on the recent methodologies aimed at preparing N-, O- and S-heterocyclic compounds in Deep Eutectic Solvents, a new class of ionic solvents that are non-volatile, non-toxic, easy to prepare, easy to recycle, and can be obtained from renewable sources. Emphasis has been placed on those processes that prioritize the recycling of catalyst and solvent, as they offer the dual benefit of promoting synthetic efficiency while demonstrating environmental responsibility.

Rational Design, Synthesis and Biological Evaluation of Novel Pyrazoline-Based Antiproliferative Agents in MCF-7 Cancer Cells

Breast cancer is a disease in which cells in the breast divide continuously without control. There are great limitations in cancer chemotherapy. Hence, it is essential to search for new cancer therapeutics. Herein, a novel series of EGFR/HER2 dual inhibitors has been designed based on the hybridization of thiazole and pyrazoline fragments. The synthesized compounds were screened for their anti-proliferative activity against MCF-7 breast cancer cell line and MCF-10 normal breast cell line. Interestingly, synthesized compounds 6e and 6k showed very potent antiproliferative activity towards MCF-7 with IC50 values of 7.21 and 8.02 µM, respectively. Furthermore, enzymatic assay was performed against EGFR and HER2 to prove the dual inhibitory action. Compounds 6e and 6k showed potent inhibitory activity for EGFR with IC50 of 0.009 and 0.051 µM, respectively, and for HER2 with IC50 of 0.013 and 0.027 µM, respectively. Additionally, compounds 6e and 6k significantly stimulated apoptotic breast cancer cell death. Compound 6e was further explored for its anticancer activity in vivo using a Xenograft model. Moreover, computational modeling studies, ADMET studies and toxicity prediction were performed to investigate their potential drug candidates.

Fluorescence "Turn-off" Sensing of Iron (III) Ions Utilizing Pyrazoline Based Sensor: Experimental and Computational Study

A simple pyrazoline-based ''turn off'' fluorescent sensor 5-(4-methoxyphenyl)-3-(5-methylfuran-2-yl)-1-phenyl-4,5-dihydro-1H-pyrazole (PFM) was synthesized and well characterized by different techniques such as FT-IR, ¹H-NMR, ¹³C-NMR, and mass spectrometry. The synthesized sensor PFM was utilized for the detection of Fe³⁺ ions. Fluorescence emission selectively quenched by Fe³⁺ ions compared to other metal ions (Mn²⁺, Al³⁺, Fe²⁺, Hg²⁺, Cu²⁺, Co²⁺, Ni²⁺, Cd²⁺, Pb²⁺, and Zn²⁺) via paramagnetic fluorescence quenching and showed good anti-interference ability over the existence of other tested metals. Under optimum conditions, the fluorescence intensity of sensor quenched by Fe³⁺ in the range of 0 to 3 μM with detection limit of 0.12 μM. Binding of Fe³⁺ ions to PFM solution were studied by fluorescent titration, revealed formation of 1:1 PFM-Fe metal complex and binding constant of complex was found to be of 1.3 × 10⁵ M^-1. Further, the fluorescent sensor has been potentially used for the detection of Fe³⁺ in environmental samples (river water, tap water, and sewage waste water) with satisfactory recovery values of 99-101%.

Synthesis of 2-Pyrazolines with a CF3- and Alkyne-Substituted Quaternary Carbon Center via [3 + 2] Cycloaddition of β-CF3-1,3-enynes and Diazoacetates

Given the importance of both the CF₃ group and the alkyne moiety in synthetic/medicinal chemistry, we report here the first example of efficient synthesis of 2-pyrazolines with a CF₃- and alkyne-substituted quaternary carbon center. This methodology has the advantages of high functional group compatibility, the avoidance of base and open-flask conditions, easily available and easy to handle reagent, and broad substrate scope. Notably, this protocol allows for the late-stage functionalization of biologically active molecules and the gram-scale synthesis.

Environmentally Benign and User-Friendly In Situ Generation of Nitrile Imines from Hydrazones for 1,3-Dipolar Cycloaddition

Nitrile imines are highly reactive and versatile dipoles and conventionally generated in situ from unstable hydrazonyl halides under basic conditions. Herein, we report the first green and user-friendly protocol for in situ generation of nitrile imines from Oxone-KBr oxidation of hydrazones and base-promoted dehydrobromination. The nitrile imines were demonstrated for 1,3-dipolar cycloaddition with various dipolarophiles, including alkene and alkyne groups. With its green nature, ease of operation, and air and moisture tolerance, we expect our method will find wide applications in organic synthesis.

Novel 2-(5-Aryl-4,5-Dihydropyrazol-1-yl)thiazol-4-One as EGFR Inhibitors: Synthesis, Biological Assessment and Molecular Docking Insights

Introduction

Epidermal growth factor receptor (EGFR) regulates several cell functions which include cell growth, survival, multiplication, differentiation, and apoptosis. Currently, EGFR kinase inhibitors are of increasing interest as promising targeted antitumor therapeutic agents.

Methods

Different thiazolyl-pyrazoline derivatives (7a-o) were synthesized and were first tested for anti-proliferative effect towards the A549 lung cancer cell line and the T-47D breast cancer cell line in MTT assay. Thereafter, thiazolyl-pyrazolines (7b, 7g, 7l, and 7m) were subsequently evaluated for their PK inhibition for EGFR. Moreover, representative promising derivatives (7g and 7m) in cytotoxic and PK inhibition assays were tested to investigate their impact on the apoptosis and cell cycle phases in T-47D cells in order to explore more insights into the antitumor actions of the target thiazolyl-pyrazolines. Furthermore, docking studies were accomplished to evaluate the patterns of binding of thiazolyl-pyrazolines 7b, 7g, 7l, and 7m in the EGFR active pocket (PDB ID: 1M17).

Results

Testing the thiazolyl pyrazoline compounds 7a-o on A549 and T-47D cell lines showed IC₅₀ arrays between 3.92 and 89.03 µM, and between 0.75 and 77.10 µM, respectively. Also, the tested thiazolyl-pyrazolines (7b, 7g, 7l, and 7m) demonstrated significant sub-micromolar EGFR inhibitory actions with IC₅₀ values 83, 262, 171 and 305 nM, respectively, in comparison to erlotinib (IC₅₀ =57 nM).

Discussion

Generally, it was observed that the tested thiazolyl pyrazolines showed more potent antiproliferative activity toward breast cancer cells T-47D than toward lung cancer cell lines A549. In particular, thiazolyl pyrazolines 7g and 7m showed the best activity against A549 cells (IC₅₀ = 3.92 and 6.53 µM) and T-47D cells (IC₅₀ = 0.88 and 0.75 µM). Compounds 7g and 7m provoked a sub-G1 phase arrest and cell apoptosis which are in agreement with the expected outcome of EGFR inhibition. Finally, the molecular docking of 7g and 7m in the active site of EGFR revealed a common binding pattern similar to that of erlotinib which involves the accommodation of the 1,3 thiazol-4-one ring and pyrazoline ring of target compounds in the binding region of erlotinib’s quinazoline ring and anilino moiety.

Synthesis and Evaluation of 1,3,5-Triaryl-2-Pyrazoline Derivatives as Potent Dual Inhibitors of Urease and α-Glucosidase Together with Their Cytotoxic, Molecular Modeling and Drug-Likeness Studies

In the present work, a concise library of 1,3,5-triaryl-2-pyrazolines (2a-2q) was designed and synthesized by employing a multistep strategy, and the newly synthesized compounds were screened for their urease and α-glucosidase inhibitory activities. The compounds (2a-2q) were characterized using a combination of several spectroscopic techniques including FT-IR, ¹H NMR, ¹³C NMR, and EI-MS. All the synthesized compounds, except compound 2i, were potent against urease as compared to the standard inhibitor thiourea (IC₅₀ = 21.37 ± 0.26 μM). These analogs disclosed varying degrees of urease inhibitory activities ranging from 9.13 ± 0.25 to 18.42 ± 0.42 μM. Compounds 2b, 2g, 2m, and 2q having IC₅₀ values of 9.36 ± 0.27, 9.13 ± 0.25, 9.18 ± 0.35, and 9.35 ± 0.35 μM, respectively, showed excellent inhibitory activity as compared to standard thiourea (IC₅₀ = 21.37 ± 0.26 μM). A kinetic study of compound 2g revealed that compound 2g inhibited urease in a competitive mode. Among the synthesized pyrazolines, the compounds 2c, 2k, 2m, and 2o exhibited excellent α-glucosidase inhibitory activity with the lowest IC₅₀ values of 212.52 ± 1.31, 237.26 ± 1.28, 138.35 ± 1.32, and 114.57 ± 1.35 μM, respectively, as compared to the standard acarbose (IC₅₀ = 375.82 ± 1.76 μM). The compounds (2a-2q) showed α-glucosidase IC₅₀ values in the range of 114.57 ± 1.35 to 462.94 ± 1.23 μM. Structure-activity relationship revealed that the size and electron-donating or -withdrawing effects of substituents influenced the activities, which led to the urease and α-glucosidase inhibiting properties. Compound 2m was a dual potent inhibitor against urease and α-glucosidase due to the presence of 2-CF₃ electron-withdrawing functionality on the phenyl ring. To the best of our knowledge, these synthetic compounds were found to be the most potent dual inhibitors of urease and α-glucosidase with minimum IC₅₀ values. The cytotoxicity of the compounds (2a-2q) was also investigated against human cell lines MCF-7 and HeLa. Compound 2l showed moderate cytotoxic activity against MCF-7 and HeLa cell lines. Moreover, in silico studies on most active compounds were also performed to understand the binding interaction of most active compounds with active sites of urease and α-glucosidase enzymes. Some compounds exhibited drug-like characteristics due to their lower cytotoxic and good ADME profiles.

Cyclization of arylhydrazones of cross-conjugated enynones: synthesis of luminescent styryl-1H-pyrazoles and propenyl-1H-pyrazoles

On the basis of available ethynyl vinyl ketones and arylhydrazines, the authors have developed the two-stage synthesis method for styrylpyrazoles possessing fluorescent abilities, as well as the gram-scale synthesis method for fluorescent probes.

Development of novel isatin thiazolyl-pyrazoline hybrids as promising antimicrobials in MDR pathogens

Microbial Multidrug Resistance (MDR) is an emerging global crisis. Derivatization of natural or synthetic scaffolds is among the most reliable strategies to search for and obtain novel antimicrobial agents for the treatment of MDR infections. Here, we successfully manipulated the synthetically flexible isatin moieties to synthesize 22 thiazolyl-pyrazolines hybrids, and assessed their potential antimicrobial activities in vitro against various MDR pathogens, using the broth microdilution calorimetric XTT reduction method. We chose 5 strains to represent the major MDR microorganisms, viz: Methicillin-resistant S. aureus (MRSA), and Vancomycin-resistant E. faecalis (VRE) as Gram-positive bacteria; Carbapenem-resistant K. pneumonia (CRKP), and Extended-spectrum beta-lactamase E. coli (ESBL-E), as Gram-negative bacteria; and Fluconazole-resistant C. albicans (FRCA), as a yeast-like unicellular fungus. The cytotoxicity of compounds 9f and 10h towards mammalian lung fibroblast (MRC-5) cells demonstrated their potential satisfactory safety margin as represented by their relatively high IC₅₀ values. The target compounds showed promising anti-MDR activities, suggesting they are potential leads for further development and in vivo studies.

As promising antimicrobials against MDR pathogens, two novel series of isatin thiazolyl-pyrazoline conjugates were developed. Compounds 9f and 10h were the most effective against the tested MDR strains.

Synthesis and Structural Characterization of Isostructural 4-(4-Aryl)-2-(5-(4-fluorophenyl)-3-(1-(4-fluorophenyl)-5-methyl-1H-1,2,3-triazol-4-yl)-4,5-dihydro-1H-pyrazol-1-yl)thiazoles

4-(4-Chlorophenyl)-2-(5-(4-fluorophenyl)-3-(1-(4-fluorophenyl)-5-methyl-1H-1,2,3-triazol-4-yl)-4,5-dihydro-1H-pyrazol-1-yl)thiazole (4) and 4-(4-fluorophenyl)-2-(5-(4-fluorophenyl)-3-(1-(4-fluorophenyl)-5-methyl-1H-1,2,3-triazol-4-yl)-4,5-dihydro-1H-pyrazol-1-yl)thiazole (5) have been synthesized in high yields. Crystallization of 4 and 5 from dimethylformamide solvent produced samples suitable for structure determination by single crystal diffraction. The materials are isostructural with triclinic, PĪ and symmetry and comprise two independent molecules in the asymmetric unit. The two independent molecules in the asymmetric unit assume similar conformation. The molecule is essentially planar apart from one of the two fluorophenyl groups, which is oriented roughly perpendicular to the plane of the rest of the molecule.

Synthesis and crystal structure of the novel chiral acetyl-3-thiophene-5-(9-anthryl)-2-pyrazoline, C23H18N2OS

C23H18Cl4N2OS, orthorhombic, P212121 (no. 19), a = 16.872(3) Å, b = 10.414(2) Å, c = 10.589(2) Å, V = 1860.5(6) Å3, Z = 4, R gt (F) = 0.0588, wR ref (F 2) = 0.1464, T = 293 K.

Tuning a pyrazoline-based fluorogenic reagent, 3-naphthyl-1-(4-trifluoromethyl)-5-(4-carboxy phenyl)-2-pyrazoline for sensitive precolumn derivatization of aliphatic alcohols and trace analysis by RP-HPLC with fluorescence detection

A new member of the pyrazoline family, 3-naphthyl-1-(4-trifluoromethyl)-5-(4-carboxy phenyl)-2-pyrazoline has been evaluated as a precolumn derivatization reagent for the analysis of primary alcohols using HPLC. The simultaneous separation of eight alcohol derivatives (C₁ -C₈ ) within 15 min was achieved on a reverse-phase C₈ column with an isocratic elution mode. The derivatives were detected with fluorescence at an emission wavelength of 470 nm when excited at 360 nm. The identification of the corresponding derivatives was carried out by LC-MS/MS and all showed their characteristic parent peak in negative ion mode. The proposed method was validated using normal analytical tools and was found to be excellent. As a preliminary application, our method was used to determine ethanol concentration in alcohol-containing chocolates and cough syrup.

Synthesis of New Bis-pyrazolines Endowed with Potent Antifungal Activity against Candida albicans and Aspergillus niger

Background:

Due to the increasing number of cases of invasive fungal infections (IFIs), there is an urgent need to identify potent antifungal agents capable of combating IFIs. Pyrazolines are one such class of therapeutically active agents that could be considered to fulfill this need.

Objective:

In this context, this paper aims to identify two new series of bis-pyrazolines endowed with potent antifungal activity against Candida albicans and Aspergillus niger.

Methods:

Two new series of bis-pyrazolines (4a-i, 5a-e) were synthesized through an efficient and versatile synthetic procedure. The compounds were screened for their antifungal effects on C. albicans and A. niger using a broth microdilution method. Their cytotoxic effects on NIH/3T3 mouse embryonic fibroblast cells were determined using MTT assay. Molecular docking studies were performed in the active site of lanosterol 14α-demethylase (CYP51) to shed light on their antifungal effects using Schrödinger’s Maestro molecular modeling package.

Results:

5,5'-(1,4-Phenylene)bis[1-(2-(5-phenyl-1,3,4-oxadiazol-2-yl)thio)acetyl)-3-(2-thienyl)-4,5- dihydro-1H-pyrazole] (4a) and 5,5'-(1,4-phenylene)bis[1-(2-(4-(2-hydroxyethyl)-1-piperazinylthiocarbamoyl) thio)acetyl)-3-(2-thienyl)-4,5-dihydro-1H-pyrazole] (5a) were found as the most promising antifungal agents in this series. Compounds 4a and 5a showed pronounced antifungal activity against C. albicans (MIC= 0.016 mg/mL) and A. niger (MIC= 0.008 mg/mL). Based on MTT assay, their antifungal effects were selective (IC50 > 0.500 mg/mL for NIH/3T3 cell line). Molecular docking studies suggested that compounds 5a-e might show their anticandidal effects via CYP51 inhibition in regard to their stronger interactions in the active site of CYP51.

Conclusion:

Compounds 4a and 5a stand out as potential antifungal agents for the management of IFIs caused by C. albicans and A. niger.

1-[5-(3,5-Dimethoxyphenyl)-3-(2-methoxyphenyl)-4,5-dihydro-1H-pyrazol-1-yl]ethanone

In the title compound, C20H22N2O4, two benzene rings bearing methoxy substituents are connected by a central acetylpyrazoline ring: the dihedral angle between the benzene rings is 83.7 (1)°. In the crystal, pairwise C—H...O hydrogen bonds generate inversion dimers and additional weak C—H...O interactions link the dimers into chains propagating along the c-axis direction.

Design, synthesis, and photophysics of bi- and tricyclic fused pyrazolines

A three series of bi-cyclic and tri-cyclic functionalised pyrazoline fluorophores with high quantum yields and positive solvato(fluoro)chromism were designed and synthesised by improved method.

Pyrazoline Hybrids as Promising Anticancer Agents: An Up-to-Date Overview

Pyrazolines are five-membered heterocycles possessing two adjacent nitrogens. They have attracted significant attention from organic and medicinal chemists due to their potent biological activities and the numerous possibilities for structural diversification. In the last decade, they have been intensively studied as targets for potential anticancer therapeutics, producing a steady yearly rise in the number of published research articles. Many pyrazoline derivatives have shown remarkable cytotoxic activities in the form of heterocyclic or non-heterocyclic based hybrids, such as with coumarins, triazoles, and steroids. The enormous amount of related literature in the last 5 years prompted us to collect all these published data from screening against cancer cell lines, or protein targets like EGFR and structure activity relationship studies. Therefore, in the present review, a comprehensive account of the compounds containing the pyrazoline nucleus will be provided. The chemical groups and the structural modifications responsible for the activity will be highlighted. Moreover, emphasis will be given on recent examples from the literature and on the work of research groups that have played a key role in the development of this field.