Search Results (66)

Late-stage metastatic cutaneous melanoma (MCM) and neuroblastoma (NB) are the most aggressive skin and childhood cancers with survival rates of <50%, mainly due to the emergence of resistance to available drugs, thus requiring an urgent solution. Quaternary phosphonium salts (QPSs) can exhibit strong anticancer effects, regardless of the developed resistance. Triphenyl (1) and diphenyl (3 and 4) phosphonium salts were synthesized, treating commercial triphenyl phosphine and synthesizing 11-diphenylphosphanyl-undecan-1-ol (2), respectively, with benzyl bromide. Upon full characterization, they were tested, for the first time, on MeTRAV (BRAF^V600D) and MeOV (BRAF^V600E) vemurafenib (PLX)-resistant MCM cells, etoposide (ETO)-sensitive (HTLA 230) and multidrug resistant (MDR) (HTLA ER) NB cells, non-tumorigenic human keratinocytes (HaCaT), and mouse embryonic fibroblasts (3T3), as well as red blood cells (RBCs). Viability of MeTRAV cells was decreased to 44.8% by administration of 1 (100 µM), in intermediate-time (48 h) treatments, while short-time exposure (24 h) to 3 (≥75 µM) and 4 (≥50 µM) was sufficient to reduce their viability to 33.6 and 32.2%. Viability of MeOV was decreased under 50% with 5 µM concentrations of 1 and 25 µM of 3 and 4, While cells were exterminated (26.9, 20.6, and 21.8%) with higher concentrations after 48 h exposure. Collectively, 1 was the better performing compound (IC₅₀ = 6.4 µM, 48 h). Viability of HTLA ER cells was decreased under 50% upon 72 h administrations of 1 at concentrations ≥ 50 µM, 48 h (≥75 µM) and 72 h (≥50 µM) of 3, and after 72 h (≥75 µM) of 4, but 72 h exposure and high concentrations of all compounds were necessary for their extermination (31.2, 28.7, and 29.7%). Viability of HTLA 230 cells was not <50% when 1 and 4 were administered for only 24 h, while their viability was <50% after administration of 3 at all times of exposure. At high concentrations, all compounds exterminated cells (33.6, 25.3%, 1, 48–72 h; 38.6, 30.2, and 24.7%, 3, 24–72 h; 33.2%, 4, 72 h). The best-performing compounds were 1 (IC₅₀ = 4.0 µM, HTLA 230) and 3 (IC₅₀ = 27.8 µM, HTLA ER) at 72 h exposure. The cytotoxic effects of compound 4 on MeTRAV cells, when exposed to 24/48 h treatments, were comparable to those of PLX on the same cells in 72 h treatments. Compound 1, in shorter 48 h treatments of PLX-R MeOV, was 2.5-fold more cytotoxic than PLX in 72 h ones. All compounds were not cytotoxic to 3T3 cells at all times of exposure; they had low cytotoxicity to HaCaT cells in 24 and 48 h treatments and were slightly cytotoxic to RBCs in 24 h ones. Compound 1 could be a promising platform to develop new intermediate-time therapies for PLX-R MeOV cells, while 4 could be used to develop 24 and 48 h treatments for PLX-R MeTRAV cells. Also, all compounds could be developed as new treatment options for both ETO-sensitive and MDR late-stage HR-NB cells, being even more effective than ETO by 1.2, 2.0, and 1.3 times (HTLA 230) and 3.2, 4.7, and 3.2 times (HTLA ER). All compounds have the potential to be developed as adjuvants in already existing anticancer cocktails to treat MCM and/or NB. Full article

Transition-metal Co²⁺ ions in halide systems are generally regarded as inefficient emitters due to rapid nonradiative relaxation of their d-d excited states. Here, we prepared two zero-dimensional (0D) organic-inorganic hybrid cobalt halides, benzyl triphenyl phosphonium bromide cobalt ((BTP)₂CoBr₄) and triphenyl phosphonium bromide cobalt ((PPh₃)₂CoBr₄), composed of [CoBr₄]²⁻ tetrahedra embedded in distinct organic frameworks. Upon Pb²⁺ incorporation, both compounds exhibit visible photoluminescence composed mainly of two emission bands centered at approximately 450 and 500 nm, with decay lifetimes on the nanosecond timescale. The emission at 450 nm originates from d-d transitions associated with short-range Co-Co ferromagnetic (FM) interactions, whereas the 500 nm emission can be attributed to donor-acceptor pair (DAP) transitions involving Co and Pb. At low temperatures, an additional broadband emission centered at ~620 nm emerges in Pb²⁺-doped (PPh₃)₂CoBr₄, with lifetimes reaching the microsecond scale, while such emission is not observed in (BTP)₂CoBr₄. Low-temperature lattice contraction in the PPh₃ framework further shortens the Co-Co distance, thereby enhancing short-range FM interactions and leading to the formation of a magnetic bipolaron for emission. Overall, this work reveals the role of organic ligand structure and dopant modulation in regulating the Co-centered excited states, providing deeper insight into the interactions between cobalt ions and organic ligands in low-dimensional halide systems. Full article

Ionic liquids (ILs) and deep eutectic solvents (DESs) have emerged as effective solvents for poorly soluble materials such as natural polysaccharides, including chitin. This review describes recently developed efficient chitin derivatization methods that harness the solubilizing power of ILs and DESs. It covers chitin acylation approaches, including acylation and mixed ester formation, as well as chitin etherification protocols. For example, the ILs 1-allyl-3-methylimidazolium bromide (AMIMBr) and 1-allyl-2,3-dimethylimidazolium bromide serve as effective media for chitin acylation and etherification, respectively, yielding single esters and benzyl derivatives with high degrees of substitution (DS). The use of DESs comprising AMIM chloride (AMIMCl) as a hydrogen bond acceptor and several hydrogen bond donors for chitin acylation are presented. In an optimized system, acylation using acyl chlorides proceeded smoothly without additives, such as a base/catalyst, in a DES comprising AMIMCl and 1,1,3,3-tetramethylguanidine, affording high-DS ester derivatives. The method was extended to the synthesis of mixed chitin esters bearing both long and bulky acyl substituents at appropriate substitution ratios, which exhibit thermoplasticity. Full article

As a continuation of our research on the synthesis and study of biological properties of new derivatives of 3-aminopyridin-2(1H)-ones, we investigated the Leuckart–Wallach and Eschweiler–Clarke reactions with selected 3-aminopyridin-2(1H)-ones and 3-(arylmethyl)pyridin-2(1H)-ones. It was found that under the conditions of the Leuckart–Wallach reaction with aromatic aldehydes in formic acid, mainly formamides of the indicated 3-aminopyridones are formed. The Eschweiler–Clarke reaction of 3-aminopyridin-2(1H)-ones and 3-(arylmethyl)pyridin-2(1H)-ones with an aqueous solution of formaldehyde result in the formation of tertiary N–benzyl(methyl)amino)-pyridin-2(1H)-ones in almost quantitative yield. The 3-aminopyridin-2(1H)-ones derivatives synthesized by us were used for the biological screening of cytoprotective activity in the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) test to determine the viability of fibroblast cells isolated from the NIH/Swiss mouse embryo (NIH/3T3, Gibco). It was found that many of the studied compounds under the conditions of our experiment exhibited significant cytoprotective effects, thereby enhancing cell survival. Full article

The transition to renewable energy makes energy storage crucial. Aqueous organic redox flow batteries (AORFBs) show great potential in large-scale energy storage due to their outstanding safety compared to conventional systems. Derivatives of 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) show significant promise as catholyte materials in AORFBs. In this work, a bipyridine-ester dual-modified TEMPO derivative, (2,2,6,6-tetramethyl-1-piperidinyloxy)carbonyl-ethyl-(4-(pyridin-4-yl)benzyl) ammonium bromide (TEMP-BPy) was successfully synthesized via a two-step functionalization. The synthesized compound was experimentally confirmed to possess excellent electrochemical stability. The electron-withdrawing effect of the 4,4′-bipyridine moiety elevates the redox potential by 60 mV. When implemented as a catholyte paired with methyl viologen (MV) as the anolyte in AORFB, the TEMP-BPy/MV system demonstrates excellent performance: achieving a cell voltage of 1.28 V and an energy density of 14.5 Wh L⁻¹ at a 0.6 M (16.08 Ah L⁻¹) concentration with 71.3% material utilization. Notably, it demonstrates exceptional cycling stability with an average capacity retention of 99.86% per cycle over 200 cycles, and it exhibits particularly impressive initial stability, with an average capacity retention of 99.997% per cycle during the first 100 cycles. Full article

Organophosphorus (OP) pesticides are a class of chemicals that are extensively used worldwide. The exposure to and use of organophosphates can be assessed by analyzing their metabolites and degradation products, such as dialkyl phosphate (DAP), dialkyl thiophosphate (DATP), and dialkyl dithiophosphate (DADTP). However, since these metabolites/hydrolysis products can result from the metabolism or breakdown of several organophosphorus pesticide families, they serve as nonspecific biomarkers and do not indicate the specific pesticide involved in exposure. In an earlier study, chemical derivatization using N-(2-(bromomethyl)benzyl)-N,N-diethylethanaminium bromide (CAX-B) was described to improve the signal intensity of numerous organophosphorus (OP) acids in liquid chromatography tandem mass spectrometry (LC-ESI-MS/MS) analysis. In the present study, CAX-B was employed to derivatize a set of seven phenolic compounds corresponding to the complementary portion of OP pesticides. The derivatization process using CAX-B was performed in acetonitrile with potassium carbonate at 50 °C for 30 min. LC-Orbitrap-ESI-MS/MS was used to analyze the resulting phenol derivatives and their fragmentation patterns were studied. Notably, the derivatized phenols were markedly more sensitive than the underivatized phenols when LC-ESI-MS/MS was used in MRM technique, without being affected by the sample matrix (soil or plant extracts). This derivatization technique aids in identifying OP pesticides, offers insights into their subfamily, and pinpoints a specific compound through the analysis of corresponding phenol derivative. Full article

Viologens, i.e., quaternary 4,4′-bipyridinum salts, are a well-known class of functional organic compounds that have attracted in the past few decades a great deal of attention for their peculiar chemical and electrochemical properties and have therefore found numerous applications ranging from herbicides to electrochromic devices. In this paper, the synthesis and characterization of a novel viologen derivative are described. In the reported compound, the pyridinium nitrogen atoms have been quaternarized with the benzyl group and an additional unsaturated moiety, namely a 9,10-diethynylanthracene core, has been inserted between the charged pyridinium rings to extend the conjugation. Characterization by means of absorbance and diffuse reflectance UV–visible spectroscopy suggested intriguing optical and electronic properties, making this extended viologen a potential candidate for different optoelectronic applications. Full article

Background/objectives: Propolis (bee glue) is a valuable bee product widely used as a natural remedy, a cosmetic ingredient, a nutritional value enhancer and a food biopreservative. The present research aims to investigate the phenolic content, antioxidant activity and in vitro anti-inflammatory and antitumor potential of six propolis samples from three regions of Bulgaria (Vidin, Gabrovo and Lovech). Methods: the analysis of propolis phenolic compounds was determined by high-performance liquid chromatography (HPLC); the antioxidant activity of ethanolic propolis extracts was assessed by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay and ferric-reducing antioxidant power (FRAP) assay; the in vitro anti-inflammatory activity was assessed by the inhibition of albumin denaturation method; the in vitro antitumor activity was determined in human metastatic breast cancer cell line MDA-MB-231 using 3-(4,5-Dimethyl -2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Results: The ethanolic propolis extracts exhibited the total phenolic content from 190.4 to 317.0 mg GAE/g, total flavonoid content from 53.4 to 79.3 mg QE/g and total caffeic acid derivatives content from 5.9 to 12.1 mg CAE/g. The studied propolis extracts showed significant antioxidant capacity (between 1000.3 and 1606.0 mM TE/g determined by the DPPH assay, and between 634.1 and 1134.5 mM TE/g determined by the FRAP assay). The chemical composition analysis indicated high concentrations of caffeic acid benzyl ester, chrysin, pinocembrin and pinobanksin-3-O-propionate, predominantly in three of the propolis samples originating from Gabrovo and Lovech regions. All propolis samples demonstrated promising in vitro anti-inflammatory activity, expressed as the inhibition of thermally induced albumin denaturation by 73.59% to 78.44%, which was higher than that of the conventional anti-inflammatory drugs Aspirin (58.44%) and Prednisolone Cortico (57.34%). The propolis samples exhibited high in vitro cytotoxicity against cancer cells MDA-MB-231 with IC₅₀ values ranging between 9.24 and 13.62 µg/mL as determined by MTT assay. Conclusions: Overall, we can suggest that the high phenolic content of Bulgarian propolis from respective areas contributes to its enhanced antioxidant, anti-inflammatory and antitumor activity. Taken together, our results support the beneficial properties of Bulgarian propolis, with potential application as a promising therapeutic agent. Full article

Naturally occurring carbohydrates serve as useful building blocks, and various derivatives have been employed in natural product syntheses. For instance, some aldoses can be converted to 1,3-dienes via the Wittig reaction at the anomeric carbon, accompanied by the E2 elimination of the C3-alkoxy group. However, there are few examples of terminal 1,3-diene synthesis. We report the synthesis of (S,Z)-1,4-bis(benzyloxy)hexa-3,5-dien-2-ol, featuring a terminal 1,3-diene and chiral secondary alcohol, derived from 2,3,5-tri-O-benzyl-d-arabinofuranose with methyltriphenylphosphonium bromide and potassium tert-butoxide in a single step. The synthesized terminal 1,3-diene demonstrated effective reactivity in a cross-metathesis reaction with cis-1,4-diacetoxy-2-butene. Full article

The selective oxidation of toluene to yield value-added oxygenates, such as benzyl alcohol, benzaldehyde, and benzoic acid, via dioxygen presents a chlorine-free approach under benign conditions. Metal-free catalytic processes are preferred to avoid metal ion contamination. In this study, we employed N-hydroxyphthalimide (NHPI) as a catalyst for the aerobic oxidation of toluene to its oxygenated derivatives. The choice of solvent exerted a significant impact on the catalytic activity and selectivity of the catalyst NHPI at reaction temperatures exceeding 70 °C. Notably, hexafluoroisopropanol substantially enhanced the selective production of benzaldehyde. Furthermore, we identified didecyl dimethyl ammonium bromide, featuring two symmetrical long hydrophobic chains, as a potent enhancer of NHPI for the solvent-free aerobic oxidation of toluene. This effect is ascribed to its unique symmetrical structure, extraction capabilities, and resistance to thermal and acid/base conditions. Based on the product distribution and control experiments, we proposed a plausible reaction mechanism. These findings may inform the industrial synthesis of oxygenated derivatives from toluene. Full article

Halide perovskite Cs₃Bi₂Br₉ (CBB) has excellent potential in photocatalysis due to its promising light-harvesting properties. However, its photocatalytic performance might be limited due to the unfavorable charge carrier migration and water-induced properties, which limit the stability and photocatalytic performance. Therefore, we address this constraint in this work by synthesizing a stable halide perovskite heterojunction by introducing hydrogen titanate nanosheets (H₂Ti₃O₇-NS, HTiO-NS). Optimizing the weight % (wt%) of CBB enables synthesizing the optimal CBB/HTiO-NS, CBHTNS heterostructure. The detailed morphology and structure characterization proved that the cubic shape of CBB is anchored on the HTiO-NS surface. The 30 wt% CBB/HTiO-NS-30 (CBHTNS-30) heterojunction showed the highest BnOH photooxidation performance with 98% conversion and 75% benzoic acid (BzA) selectivity at 2 h under blue light irradiation. Detailed optical and photoelectrochemical characterization showed that the incorporating CBB and HTiO-NS widened the range of the visible-light response and improved the ability to separate the photo-induced charge carriers. The presence of HTiO-NS has increased the oxidative properties, possibly by charge separation in the heterojunction, which facilitated the generation of superoxide and hydroxyl radicals. A possible reaction pathway for the photocatalytic oxidation of BnOH to BzH and BzA was also suggested. Furthermore, through scavenger experiments, we found that the photogenerated h⁺, e⁻ and •O₂⁻ play an essential role in the BnOH photooxidation, while the •OH have a minor effect on the reaction. This work may provide a strategy for using HTiO-NS-based photocatalyst to enhance the charge carrier migration and photocatalytic performance of CBB. Full article

Organobentonites have been applied for the removal of two common non-steroidal anti-inflammatory drugs, ibuprofen (IBU) and diclofenac sodium (DS), from aqueous solutions. Two surfactants, one with and the other without benzyl group (octadecyldimethylbenzylammonium chloride, ODMBA, and hexadecyltrimethylammonium bromide, HDTMA), in amounts equivalent to 50, 75, and 100% of the cation exchange capacity of bentonite were used for the preparation of organobentonites. Successful modification of bentonite was confirmed by several methods: X-ray powder diffraction (XRPD), point of the zero charge (pH_PZC), determination of exchanged inorganic cations in bentonite, determination of textural properties, and scanning electron microscopy (SEM). Kinetic and thermodynamic data on the adsorption of IBU and DS showed that drug adsorption was controlled by the type and the amount of surfactant incorporated into the bentonite and by their arrangement in the interlayer space and at the surface of organobentonites. The adsorption of both drugs increased with an increase in the amount of both surfactants in organobentonites. The presence of the benzyl group in organobentonites enhanced the adsorption of IBU and DS and was more pronounced for IBU. Drug adsorption fits the pseudo-second-order kinetic model the best. The thermodynamic data revealed that the adsorption process was endothermic in nature and with increase of the amount of both surfactants drug adsorption processes were more spontaneous. The results obtained from this study revealed that adsorbents based on surfactants modified bentonite are promising candidates for IBU and DS removal from contaminated water. Full article

In this work, we report the unexpected conversion of a pyridine derivative into the corresponding N-benzylated pyridinium salt due to the presence of unreacted benzyl bromide in the crude product. This transformation was observed at room temperature in a solvent-free environment and without any stirring. These interesting data show how pyridinium salts can be formed in mild conditions, avoiding high temperatures that could promote the degradation of the desired product. Full article

The reactivity of the open-shell Gd@C_2v-C₈₂ with different charge states towards benzyl bromide was investigated. [Gd@C_2v-C₈₂]³⁻ exhibited enhanced activity relative to Gd@C_2v-C₈₂ and [Gd@C_2v-C₈₂]⁻. The structural characterizations, including MALDI-TOF MS, UV-vis-NIR, and single crystal X-ray diffraction, indicate the formation of isomeric benzyl monoadducts of Gd@C_2v-C₈₂. All three monoadducts contain 1:1 mirror-symmetric enantiomers. Additionally, the addition of the benzyl group and its specific position result in distinct electrochemical behavior of the products compared to the parent Gd@C_2v-C₈₂. Theoretical studies demonstrate that only [Gd@C_2v-C₈₂]³⁻ has a HOMO energy level that matches well with the LUMO energy level of the PhCH₂ radical, providing a rationalization for the observed significantly different reactivity. Full article

The chemical derivatization to enhance the signal intensity and signal-to-noise (S/N) of several organophosphorus (OP) acids in liquid chromatography tandem mass spectrometry (LC-ESI-MS/MS) is illustrated. The OP class of compounds represents the environmental degradants of OP nerve agents and pesticides. N-(2-(bromomethyl)benzyl)-N,N-diethylethanaminium bromide (CAX-B) was utilized to derivatize a panel of eight acids consisting of five alkyl methylphosphonic acids (ethyl-, isopropyl-, isobutyl-, cyclohexyl-, and pinacolyl-methylphosphonic acid) along with three dialkylphosphate analogs (diethyl-, dibutyl-, and diethyl thio-phosphate). The derivatization reaction with CAX-B was conducted in acetonitrile in the presence of potassium carbonate at 70 °C for 1 h. The resulting acid derivatives were analyzed with an LC-Orbitrap-ESI-MS/MS, and their dissociation processes were investigated. It was found that the derivatization procedure increased the limits of identification (LOIs) by one to over two orders of magnitude from the range of 1 to 10 ng/mL for the intact OP-acids to the range of 0.02–0.2 ng/mL for the derivatized acids utilizing an LC-MS(QqQ) in MRM mode, regardless of the sample matrix (hair, concrete, or plant extracts). The interpretation of the corresponding ESI-MS/MS spectra for each type of derivatized sub-OP family revealed the formation of characteristic neutral losses and a characteristic ion for the organophosphorus core. This derivatization is beneficial and useful for screening and identifying target and “unknown” OP acids. Full article