Novel Structural Motifs Consisting of Chiral Thiazolines: Synthesis, Molecular Recognition, and Anticancer Activity

New N-Adducts of Thiadiazole and Thiazoline with Levoglucosenone and Evaluation of Their Significant Cytotoxic (Anti-Cancer) Activity

The conjugate N-adducts of thio-1,3,4-diazole and 2-thiazoline with levoglucosenone were synthesized via a stereoselective, base-catalyzed conjugate N-Michael addition to levoglucosenone at C-4. Structural assignments were established using 1H and 13C NMR analysis, and X-ray single-crystal analysis for one of the compounds. The biological properties of the novel compounds were tested on a cell model. Cytotoxicity was analyzed via colorimetric assay. Two distinct types of cell death, apoptosis and necrosis, were analyzed by determining the phosphatidylserine levels from the outer leaflet of the plasma membrane, caspase activation, and lactate dehydrogenase release. We also evaluated DNA damage using an alkaline comet assay. The level of oxidative stress was measured with a modified comet assay and an H2DCFDA probe. The thio-1,3,4-diazole adduct (FCP23) and the 2-thiazoline adduct (FCP26) exhibit similar cytotoxicity values for cancer cells (ovarian (A2780), breast (MCF-7), cervix (HeLa), colon (LoVo), and brain (MO59J and MO59K)), but their mechanism of action is drastically different. While FCP23 induces oxidative stress, DNA damage, and necrosis, FCP26 induces apoptosis through caspase activation.

Recent advances in the synthesis and utility of thiazoline and its derivatives

Thiazolines and their derivatives hold significant importance in the field of medicinal chemistry due to their promising potential as pharmaceutical agents. These molecular entities serve as critical scaffolds within numerous natural products, including curacin A, thiangazole, and mirabazole, and play a vital role in a wide array of physiological reactions. Their pharmacological versatility encompasses anti-HIV, neurological, anti-cancer, and antibiotic activities. Over the course of recent decades, researchers have extensively explored and developed analogs of these compounds, uncovering compelling therapeutic properties such as antioxidant, anti-tumor, anti-microbial, and anti-inflammatory effects. Consequently, thiazoline-based compounds have emerged as noteworthy targets for synthetic endeavors. In this review, we provide a comprehensive summary of recent advancements in the synthesis of thiazolines and thiazoline-based derivatives, along with an exploration of their diverse potential applications across various scientific domains.

Influence of ligand lipophilicity in Pt(II) complexes on their antiproliferative and apoptotic activities in tumour cell lines

One of the most widely used strategies for drug development is the coordination of bioactive ligands to transition metals, which could improve biological activity. Moreover, the incorporation of aromatic groups to ligands may allow an enhanced lipophilicity that can influence the cellular uptake and accumulation of the metallodrugs, thus increasing their activity. Herein, we have reported the synthesis and characterization of four Pt(II) complexes [PtCl₂(L)], where L = 2-(1-pyrazolyl)-2-thiazoline (PzTn), 2-(1-pyrazolyl)-1,3-thiazine (PzTz), 2-(3,5-diphenyl-1-pyrazolyl)-2-thiazoline (DPhPzTn) or 2-(3,5-diphenyl-1-pyrazolyl)-1,3-thiazine (DPhPzTz). The study was aimed at analysing their potential anticarcinogenic ability in epithelial cervix carcinoma HeLa, human promyelocytic leukemia HL-60 and human histiocytic lymphoma U-937 tumour cell lines as well as checking whether the structural factors of the organic ligand may influence their biological activity. Our findings showed that PtDPhPzTn and PtDPhPzTz were far more effective in terms of cytotoxicity than their less lipophilic counterparts (PtPzTn and PtPzTz), especially in cells derived from solid cervical tumours, thereby suggesting that modulating the lipophilicity of the ligands can help improve the cytotoxic effect of the metal complexes.

Synthesis and structure of a new thiazoline-based palladium(II) complex that promotes cytotoxicity and apoptosis of human promyelocytic leukemia HL-60 cells

Cisplatin is one of the most widely used chemotherapeutic agents in the treatment of different tumors but has high toxicity and side effects. Therefore, the synthesis of new chemotherapeutic agents is necessary, so that they are effective in the treatment of cancer while avoiding such toxicity. In this study, we have synthesized and characterized a palladium(II) complex, [PdCl2(µ-PyTT)2]Cl2·4H2O (PdPyTT), with 2-(2-pyridyl)imine-N-(2-thiazolin-2-yl)thiazolidine (PyTT) as a ligand; besides, its cytotoxicity and pro-apoptotic capacity was tested in human promyelocytic leukemia HL-60 cell line. Similar to cisplatin, PdPyTT produced a time- and dose-dependent decrease in cell viability. Additionally, the palladium complex increased both the proportion of cells with apoptotic morphology and the activation of caspase-3 and -9. PdPyTT, like cisplatin, also increased intracellular ROS production and DNA oxidative damage. Therefore, our findings demonstrated the promising application of palladium(II) complexes as novel anti-leukemic agents.

Diverse N-Substituted Azole-Containing Amino Acids as Building Blocks for Cyclopeptides

The preparation of 16 oxazole- or thiazole-containing amino esters bearing a wide array of N-substitution is reported. These were accessed in 40-92% yield via an AgClO4-promoted substitution reaction between a primary amine and a chloromethyl-functionalized thiazole or oxazole. These new synthetic building blocks will be useful for the preparation of new cyclopeptide analogues bearing heterocyclic backbone modifications. Four macrocyclic N-substituted oligoamides that include thiazole or oxazole heterocycles were obtained, following cyclooligomerization reactions of azole-modified N-substituted amino acids.

Pt(II) and Pd(II) complexes with a thiazoline derivative ligand: Synthesis, structural characterization, antiproliferative activity and evaluation of pro-apoptotic ability in tumor cell lines HT-29 and U-937

Eluding apoptosis represents the hallmark of tumoral cell behavior. Cisplatin (CisPt) is a very common chemotherapeutic agent to treat cancer by reestablishing apoptotic mechanisms of cell death. However, certain patients acquire resistance to CisPt as well as suffer nephrotoxicity, neurotoxicity, nausea and vomiting. The synthesis of new Pt(II) compounds represents an alternative to CisPt to avoid resistance and undesirable side effects. Pd(II) could be a Pt(II) surrogate given the similarity of coordination chemistry between them, thus widening the spectra of available anticancer drugs. Herein, we have synthesized and characterized two Pt(II) or Pd(II) complexes with TdTn (2-(3,4-dichlorophenyl)imino-N-(2-thiazolin-2-yl)thiazolidine), a thiazoline derivative ligand, with formula [PtCl₂(TdTn)] and [PdCl₂(TdTn)]. The potential anticancer ability was evaluated in human colon adenocarcinoma HT-29 and human histiocytic lymphoma U-937 cell lines. To that aim, U-937 and HT-29 cells were treated with TdTn, [PtCl₂(TdTn)] and [PdCl₂(TdTn)] for 24 h. The microscopy monitoring indicated that TdTn, [PtCl₂(TdTn)] and [PdCl₂(TdTn)] arrested the cell proliferation of U-937 and HT-29 cells with respect to control, in agreement with MTT (3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide) analysis. Moreover, it is noteworthy that the ligand by its own showed antiproliferative effects in both cell lines. [PtCl₂(TdTn)] and [PdCl₂(TdTn)] caused caspase-3 activation in U-937 cells, simultaneously with caspase-9 activation due to complexes; however, in HT-29 caspase-3 activation occurred simultaneously with caspase-8 activation induced by the ligand TdTn. Only metal complexes were able to induce ROS (Reactive Oxygen Species) generation in U-937 cells, but not TdTn. In HT-29 cells neither the metal complexes, nor the ligand induced ROS generation.

New Thiazoline-Tetralin Derivatives and Biological Activity Evaluation

In this study, novel N′-(3-cyclohexyl/phenyl-4-(substituted phenyl)thiazole-2(3H)-ylidene)-2-[(5,6,7,8-tetrahydronaphthalen-2-yl)oxy]acetohydrazide (4a–4k) derivatives were synthesized and their anticancer potency were evaluated on human breast adenocarcinoma cell line (MCF-7), human lung carcinoma cell line (A549) and mouse embryoblast cell line (NIH/3T3) using the MTT method, DNA synthesis inhibition and flow cytometric analysis. Compound 4e bearing 4-methoxyphenyl moiety exhibited the highest antitumor efficiency against MCF-7 cell line with higher DNA synthesis inhibition and apoptotic cell percentages (ealy+late apoptotic cell). On the other hand, compounds 4f, 4g, and 4h bearing 4-bromo, 4-chloro and 4-florophenyl moieties, respectively caused excellent apoptosis levels against A549 cell line when treated with lower concentration even than cisplatin. Anticholinesterase activity of the compounds were also tested, compound 4h showed 49.92% inhibition of acetylcholinesterase (AChE).

N-Propargylamines: versatile building blocks in the construction of thiazole cores

Thiazoles and their hydrogenated analogues are not only key structural units in a wide variety of natural products but they also constitute important building blocks in medicinal chemistry. Therefore, the synthesis of these compounds using new protocols is always interesting. It is well known that N-propargylamines can undergo a number of cyclization reactions to produce various nitrogen-containing heterocycles. In this review, we highlight the most important developments on the synthesis of thiazole and its derivatives starting from N-propargylamines. This review will be helpful in the development of improved methods for the synthesis of natural and biologically important compounds.

Recent progress in the identification of selective butyrylcholinesterase inhibitors for Alzheimer's disease

Alzheimer's disease (AD) is one of the most prevalent neurodegenerative disorders with notable factor of dysfunction in cholinergic system. Low ACh level can be observed in the pathogenesis of AD. Several AChE inhibitors have already been used for clinical treatments. However, other than normal conditions, ACh is mostly hydrolyzed by BuChE in progressed AD. Account for an increased level of BuChE and decreased level of AChE in the late stage of AD, development of selective BuChE inhibitor is of vital importance. Up till now, compounds with various scaffolds have been discovered to selectively inhibit BuChE. Different effective anti-BuChE molecules are concluded in this review.

Synthesis of amidine and bis amidine derivatives and their evaluation for anti-inflammatory and anticancer activity

2-Cyanopyridine (1a), 4-cyanopyridine (1b), 2-cyanopyrazine (1c) on condensation with mono amines (2a-c) and diamines (4a-c) in the presence of sodium methoxide as catalyst gave amidine derivatives (3a-i) and bis amidine derivatives (5a-i) in good yields. All these compounds were fully characterized by spectroscopic means and elemental analysis. On screening for anti-inflammatory activity and for in vitro anticancer activity compounds 5c and 5d exhibited good anti-inflammatory activity whereas compounds 5d breast (T47D), 5h, 5i lung (NCI H-522), 5i colon (HCT-15), 3c, 3h, 5i ovary (PA-1) and 3c, 5b, 5h liver (HepG2) exhibited good anticancer activity.

Comparison of the reactivity of β-thiolactones and β-lactones toward ring-opening by thiols and amines

An investigation into the comparative reactivity of simple β-lactones and β-thiolactones toward a thiol and a primary amine is reported. A simple 3-mercaptomethyl-2-oxetanone is found to undergo rearrangement in the presence of aqueous base to give the corresponding thietane-3-carboxylic acid rather than the 3-hydroxymethyl-2-thietanone. Implications for the use of β-thiolactones in bioorganic and medicinal chemistry are discussed.

Application of molecular topology for the prediction of reaction yields and anti-inflammatory activity of heterocyclic amidine derivatives

Topological-mathematical models based on multiple linear regression analyses have been built to predict the reaction yields and the anti-inflammatory activity of a set of heterocylic amidine derivatives, synthesized under environmental friendly conditions, using microwave irradiation. Two models with three variables each were selected. The models were validated by cross-validation and randomization tests. The final outcome demonstrates a good agreement between the predicted and experimental results, confirming the robustness of the method. These models also enabled the screening of virtual libraries for new amidine derivatives predicted to show higher values of reaction yields and anti-inflammatory activity.

Synthesis, anticancer, and anti-inflammatory activity evaluation of methanesulfonamide and amidine derivatives of 3,4-diaryl-2-imino-4-thiazolines

Condensation of 3,4-diaryl-2-imino-4-thiazoli-nes 1a-j with methanesulfonyl chloride gave methanesulfonamide derivatives 2a-j. Condensation of 2-cyanopyrazine, 4-cyanopyridine, and 2-cyanopyridine with 3,4-diaryl-2- imino-4-thiazolines 1h-m in the presence of sodium methoxide afforded amidine derivatives 3a-j. Compounds 2a-j and 3a-j were screened against various human cancer cell lines (COLO-205, HEP-2, A-549, IMR-32) and their percentage growth inhibition profile determined at 1 x 10(-5)M. The anti-inflammatory activity of these compounds was assessed using the carrageenan-induced paw edema model. Compound 2i exhibited 34.7% anti-inflammatory activity at 50 mg/kg p.o., which is comparable to standard care drug phenyl butazone (37% activity at 50 mg/kg p.o.).

Design and synthesis of thiazoline–thiazole hybrid macrocycles possessing strong binding affinity to Pb2+ and Cd2+

Thiazoline-thiazole hybrid macrocycles were synthesized via head-to-tail cyclooligomerization. The macrocycle consisting of eight heterocyclic subunits displays high binding affinity to the heavy metal toxins Pb(2+) and Cd(2+).