Promising near-infrared non-targeted probes: benzothiazole heptamethine cyanine dyes

NIR pH-Responsive PEGylated PLGA Nanoparticles as Effective Phototoxic Agents in Resistant PDAC Cells

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers worldwide due to its resistance to conventional therapies that is attributed to its dense and acidic tumor microenvironment. Chemotherapy based on gemcitabine usually lacks efficacy due to poor drug penetration and the metabolic characteristics of the cells adapted to grow at a more acidic pHe, thus presenting a more aggressive phenotype. In this context, photodynamic therapy (PDT) offers a promising alternative since it generally does not suffer from the same patterns of cross-resistance observed with chemotherapy drugs. In the present work, a novel bromine-substituted heptamethine-cyanine dye (BrCY7) was synthesized, loaded into PEG-PLGA NPs, and tested on the pancreatic ductal adenocarcinoma cell line cultured under physiological (PANC-1 CT) and acidic (PANC-1 pH selected) conditions, which promotes the selection of a more aggressive phenotype. The cytotoxicity of BrCY7-PEG-PLGA is dose-dependent, with an IC50 of 2.15 µM in PANC-1 CT and 2.87 µM in PANC-1 pH selected. Notably, BrCY7-PEG-PLGA demonstrated a phototoxic effect against PANC-1 pH selected cells but not on PANC-1 CT, which makes these findings particularly relevant since PANC-1 pH selected cells are more resistant to gemcitabine as compared with PANC-1 CT cells.

Oxidative damage and cardiotoxicity induced by 2-aminobenzothiazole in zebrafish (Danio rerio)

There is limited information available on cardiovascular toxicity of 2-Aminobenzothiazole (NTH), a derivative of benzothiazole (BTH) commonly used in tire production, in aquatic organisms. In the present study, the zebrafish embryos were exposed to varying concentrations of NTH (0, 0.05, 0.5, and 5 mg/L) until adulthood and the potential cardiovascular toxicity was assessed. NTH exposure resulted in striking aberrations in cardiac development, including heart looping failure and interference with atrioventricular canal differentiation. RNA-sequencing analysis indicated that NTH causes oxidative damage to the heart via ferroptosis, leading to oxygen supply disruption, cardiac malformation, and ultimately, zebrafish death. Quantitative real-time polymerase chain reaction (qPCR) analysis demonstrated the dysregulation of genes associated with early heart development, contraction, and oxidative stress. Additionally, reactive oxygen species accumulation and glutathione/malondialdehyde levels changes suggested a potential link between cardiac developmental toxicity and oxidative stress. In adult zebrafish, NTH exposure led to ventricular enlargement, decreased heart rate, reduced blood flow, and prolonged RR, QRS, and QTc intervals. To the best of our knowledge, this study is the first to provide evidence of cardiac toxicity and the adverse effects of ontogenetic NTH exposure in zebrafish, revealing the underlying toxic mechanisms connected with oxidative stress damage. These findings may provide crucial insights into the environmental risks associated with NTH and other BTHs.

Carbocyanine-Based Optical Sensor Array for the Discrimination of Proteins and Rennet Samples Using Hypochlorite Oxidation

Optical sensor arrays are widely used in obtaining fingerprints of samples, allowing for solutions of recognition and identification problems. An approach to extending the functionality of the sensor arrays is using a kinetic factor by conducting indicator reactions that proceed at measurable rates. In this study, we propose a method for the discrimination of proteins based on their oxidation by sodium hypochlorite with the formation of the products, which, in turn, feature oxidation properties. As reducing agents to visualize these products, carbocyanine dyes IR-783 and Cy5.5-COOH are added to the reaction mixture at pH 5.3, and different spectral characteristics are registered every several minutes (absorbance in the visible region and fluorescence under excitation by UV (254 and 365 nm) and red light). The intensities of the photographic images of the 96-well plate are processed by principal component analysis (PCA) and linear discriminant analysis (LDA). Six model proteins (bovine and human serum albumins, γ-globulin, lysozyme, pepsin, and proteinase K) and 10 rennet samples (mixtures of chymosin and pepsin from different manufacturers) are recognized by the proposed method. The method is rapid and simple and uses only commercially available reagents.

Benzothiazole Derivatives as Multifunctional Antioxidant Agents for Skin Damage: Structure–Activity Relationship of a Scaffold Bearing a Five-Membered Ring System

Skin diseases often give multifactorial damages; therefore, the development of multifunctional compounds represents a suitable approach especially against disorders that are induced by oxidative stress. Thus, taking into account the successful results we achieved on benzimidazoles, we have devised a new series of isosteric benzothiazoles and investigated their antioxidant, photoprotective, antifungal and antiproliferative activity. Particular attention has been paid to synergistic antioxidant and photoprotective properties. For compounds 9a and 10a, a multifunctional profile was outlined, supported by an excellent filtering capacity, mainly UVB, which has higher capacities than those of the reference PBSA which is currently in the market as a UV sunscreen filter. The two compounds were also the best in terms of growth inhibition of dermatophytes and Candida albicans, and 10a also showed good antioxidant activity. Furthermore, 9a was also effective on melanoma tumor cells (SK-Mel 5), making these compounds good candidates in the development of new skin protective and preventive agents.

Deuterated Indocyanine Green (ICG) with Extended Aqueous Storage Shelf-Life: Chemical and Clinical Implications

Indocyanine Green (ICG) is a clinically approved near-infrared fluorescent dye that is used extensively for various imaging and diagnostic procedures. One drawback with ICG is its instability in water, which means that reconstituted clinical doses have to be used very shortly after preparation. Two deuterated versions of ICG were prepared with deuterium atoms on the heptamethine chain, and the spectral, physiochemical, and photostability properties were quantified. A notable mechanistic finding is that self-aggregation of ICG in water strongly favors dye degradation by a photochemical oxidative dimerization reaction that gives a nonfluorescent product. Storage stability studies showed that replacement of C-H with C-D decreased the dimerization rate constant by a factor of 3.1, and it is likely that many medical and preclinical procedures will benefit from the longer shelf-lives of these two deuterated ICG dyes. The discovery that ICG self-aggregation promotes photoinduced electron transfer can be exploited as a new paradigm for next-generation photodynamic therapies.

Photochemical synthesis, intercalation with DNA and antitumor evaluation in vitro of benzo[d]thiazolo[3,2-a]quinolin-10-ium derivatives

A new anticancer benzo[d]thiazolo[3,2-a]quinolin-10-ium derivatives were synthesized and characterized. Anticancer evaluation in vitro against four cancer cell lines including adenocarcinomic human alveolar basal epithelial cells (A549), hepatocellular carcinoma (HepG2), prostate cancer (PC3) and breast cancer (MCF7) indicated that some of prepared compounds shows higher selectivity in comparison with doxorubicin. DNA interaction studies by optical, CD, NMR spectroscopies showed the high affinity of benzothiazole ligands towards the dsDNA. The ligand-DNA interaction occurs through the intercalation of benzo[d]thiazolo[3,2-a]quinolin-10-ium derivatives with nucleic acid. The investigation of formed ligand - DNA complexes by docking and molecular dynamic calculations was applied for analysis of the relationship between structure and anticancer activity. The results suggested that benzo[d]thiazolo[3,2-a]quinolin-10-ium derivatives might serve as a novel scaffold for the future development to new antitumor agents.

Development of β-carboline-benzothiazole hybrids via carboxamide formation as cytotoxic agents: DNA intercalative topoisomerase IIα inhibition and apoptosis induction

In quest of promising anticancer agents, the pharmacophores of natural (β-carboline) and synthetic origin (benzothiazole) were adjoined by a carboxamide bridge and three-point diversification was accomplished. The in vitro cytotoxic ability of the compounds was established on adherent and suspension human cancer cell lines and compounds 8u and 8f advanced as pre-eminent molecules with IC₅₀ values of 1.46 and 1.81 μM respectively in A549 cell line. The cytospecificity was entrenched for potent compounds 8u and 8f by evaluating against normal human lung epithelial cells and selectivity index was calculated. Furthermore, EtBr displacement, relative viscosity and gel-based topoisomerase II target assays unveiled the intercalative topo-II inhibitory capability and DNA binding studies (absorbance) revealed the dissociation constant (K_d) for compounds 8u and 8f as 98 and 103 μM respectively. Additionally, cell-based flow cytometric assays like Annexin-V/PI dual staining aids in the quantification of apoptosis induced and JC-1 staining disclosed the depolarization of mitochondrial membrane potential by compound 8u in A549 cells in a dose-dependent manner. Moreover, wound healing assay established the inhibition of in vitro cell migration by compound 8u on A549 cells. In addition, molecular docking studies proved the binding of compounds 8u and 8f in the active site of DNA complexed with topo IIα and stabilized by interactions with DNA base pairs and amino acid residues. Remarkably, the compounds 8u and 8f follow Lipinski's rule of five and are in the recommended range for Jorgensen's rule of three with a minimal violation and other pharmacokinetic parameters revealing druggability of the synthesized hybrids.

N-alkylated linear heptamethine polyenes as potent non-azole leads against Candida albicans fungal infections

In this study, eighteen heptamethine dyes were synthesised and their antifungal activities were evaluated against three clinically relevant yeast species.. The eighteen dyes were placed within classes based on their core subunit i.e. 2,3,3-trimethylindolenine (5a-f), 1,1,2-trimethyl-1H-benzo[e]indole (6a-f), or 2-methylbenzothiazole (7a-f). The results presented herein imply that the three families of cyanine dyes, in particular compounds 5a-f, show high potential as selective scaffolds to treat C. albicans infections. This opens up the opportunity for further optimisation and investigation of this class compounds for potential antifungal treatment.

Coumarin Tröger's base derivatives with cyanine substitution as selective and sensitive fluorescent lysosomal probes

The fluorescent probes based on Tröger's base motive with both coumarin and cyanine substitution 11-13 have been synthesized by multi-step synthesis in high overall yields. Intracellular localization of prepared probes have been tested using four different cell lines (HF-P4, BLM, U-2 OS and A-2058). Prepared probes have intensive green and red fluorescence. Co-localization with commercial lysosome specific marker LysoTracker Blue DND 22 has been confirmed that all prepared fluorescent probes labeled lysosomal compartment with high selectivity and probes show excellent brightness at low concentration.

New Polyfluorinated Cyanine Dyes for Selective NIR Staining of Mitochondria

In this communication, the synthesis of three unknown polyfluorinated cyanine dyes and their application as selective markers for mitochondria are presented. By incorporating fluorous side chains into cyanine dyes, their remarkable photophysical properties were enhanced. To investigate their biological application, several different cell lines were incubated with the synthesized cyanine dyes. It was discovered that the presented dyes can be utilized for selective near-infrared-light (NIR) staining of mitochondria, with very low cytotoxicity determined by MTT assay. This is the first time that polyfluorinated cyanine fluorophores are presented as selective markers for mitochondria. Due to the versatile applications of polyfluorinated fluorophores in bioimaging and materials science, it is expected that the presented fluorophores will be stimulating for the scientific community.

A comprehensive review in current developments of benzothiazole-based molecules in medicinal chemistry

Benzothiazole (BTA) and its derivatives are the most important heterocyclic compounds, which are common and integral feature of a variety of natural products and pharmaceutical agents. BTA shows a variety of pharmacological properties, and its analogs offer a high degree of structural diversity that has proven useful for the search of new therapeutic agents. The broad spectrum of pharmacological activity in individual BTA derivative indicates that, this series of compounds is of an undoubted interest. The related research and developments in BTA-based medicinal chemistry have become a rapidly developing and increasingly active topic. Particularly, numerous BTA-based compounds as clinical drugs have been extensively used in practice to treat various types of diseases with high therapeutic potency. This work systematically gives a comprehensive review in current developments of BTA-based compounds in the whole range of medicinal chemistry as anticancer, antibacterial, antifungal, antiinflammatory, analgesic, anti-HIV, antioxidant, anticonvulsant, antitubercular, antidiabetic, antileishmanial, antihistaminic, antimalarial and other medicinal agents. It is believed that, this review article is helpful for new thoughts in the quest for rational designs of more active and less toxic BTA-based drugs, as well as more effective diagnostic agents and pathologic probes.