Chloro Derivatives Research Articles

Synthesis, antimalarial activity assay and molecular docking study of N-substituted chloro-pyrazolines

Purpose: To synthesize chloro-pyrazolines (A–D), determine their antimalarial activity against Plasmodium falciparum strain 3D7 in vitro, and understand the interaction between falcipain-2 active sites and synthesized compounds by molecular docking simulation.Methods: Chloro-pyrazolines (A–D) were synthesized via cyclo-condensation of 4-chloro chalcone derivatives using several types of hydrazines, i.e., formylhydrazine, benzoylhydrazine, phenylhydrazine and chlorophenylhydrazine. The compounds were analyzed and subjected to antimalarial assay against P. falciparum 3D7. Molecular docking was performed using AutoDock Tools and AutoDock Vina, while each docked compound was visualized using Discovery Studio Visualizer.Results: Pyrazolines A–D yield was 87.09, 61.71, 50.24 and 57.64 %, respectively. Antimalarial assay showed half-maximal inhibitory concentration (IC50) values of 16.46 and 5.55 μM for pyrazoline A and B, respectively, and ≥ 100 μM for pyrazoline C and D. Molecular docking study revealed that pyrazolines A–D had good interaction with the active site of falcipain-2 receptor.Conclusion: A series of N-substituted chloro-pyrazolines has successfully been synthesized with moderate yield. Pyrazoline B has the highest antimalarial activity against P. falciparum 3D7 with IC50 of 5.55 μM. This finding is supported by molecular docking and indicates that the benzoyl substituent increases the antimalarial activity of pyrazoline B. Pyrazoline B has potentials for clinical application as an antimalaria agent.

Synthesis, molecular modeling and antioxidant screening of new thioether-bridged thiadiazole and thiadiazolopyrimidine analogues

The N-aryl-2-((5-(2-cyanoacetamido)-1,3,4-thiadiazol-2-yl)thio)acetamide derivatives 3a-c were prepared and successfully reacted with N,N-dimethylformamide dimethyl acetal (DMF-DMA). The resulting N-thiadiazolyl-2-cyano-3-(dimethylamino)acrylamide derivatives 4a-c were cyclized in boiling acetic acid to yield the corresponding thiadiazolopyrimidine compounds 5a-c. The structural properties of synthesized compounds were studied using DFT/B3LYP level. The HOMO-LUMO energies were employed in determination of some chemical reactivity descriptors. Despite the close energy gap values (ΔEH-L) of the investigated compounds, the data showed that chloro derivatives has the highest energy gap while the methoxy derivatives were the lowest. The synthesized compounds were investigated to explore their antioxidant activities. The results showed that the N-thiadiazolyl-2-cyano-3-(dimethylamino)acrylamides 4a-c had higher inhibition IC50 values (24.27–31.64 µg/mL) than the thiadiazolyl cyanoacetamides 3a-c (34.26–39.33 µg/mL). However, thiadiazolopyrimidines 5a-c presented moderate inhibition with (IC50 = 40.21–44.19 µg/mL) in comparison to ascorbic acid and BHT (Butylated hydroxytoluene) as reference drugs with IC50 = 22.66 and 27.24 µg/mL, respectively. Furthermore, the synthesized compounds were evaluated against (PDB Code-3ML5) using the MOE operation v10.2015.10 database. The inspected synthesized thiadiazole derivatives 3, 4 and 5 revealed H-bond linkages over the receptor through the disparate polar amino acids (Thr 200, Thr 199, Gln 67, His 94, and Lys 91) of larger pocket size of 3ML5. The results of the docking study presented a remarkable agreement with the practical results of the antioxidant activity.

Synthesis and Biological Evaluation of Small Molecules as Potential Anticancer Multitarget Agents.

Twenty-six triazole-based derivatives were designed for targeting both PD-L1 (programmed death receptor ligand 1) and VEGFR-2 (vascular endothelial growth factor receptor 2). These compounds were synthetized and biologically evaluated as multitarget inhibitors of VEGFR-2, PD-L1 and c-Myc proteins. The antiproliferative activity of these molecules on several tumor cell lines (HT-29, A-549, and MCF-7) and on the non-tumor cell line HEK-293 was determined. The effects on the abovementioned biological targets were evaluated for some selected compounds. Compound 23, bearing a p-chlorophenyl group, showed better results than sorafenib in regard to the downregulation of VEGFR-2 and a similar effect to BMS-8 on both PD-L1 and c-Myc proteins. The antiangiogenic and antivascular activities of chloro derivatives were also established by endothelial microtube formation assay on Matrigel®.

Synthesis, antiplasmodial activity and in silico molecular docking study of pinocembrin and its analogs

BackgroundMalaria remains the major health problem responsible for many mortality and morbidity in developing countries. Because of the development of resistance by Plasmodium species, searching effective antimalarial agents becomes increasingly important. Pinocembrin is a flavanone previously isolated as the most active antiplasmodial compound from the leaves of Dodonaea angustifolia. For a better understanding of the antiplasmodial activity, the synthesis of pinocembrin and a great number of analogs was undertaken.MethodsChalcones 5a-r were synthesized via Claisen-Schmidt condensation using 2,4-dibenzyloxy-6-hydroxyacetophenone and aromatic aldehydes as substrates under basic conditions. Cyclization of compounds 5a-r to the corresponding dibenzylated pinocembrin analogs 6a-r was achieved using NaOAc in EtOH under reflux. Catalytic hydrogenation using 10% Pd/C as catalyst in an H-Cube Pro was used for debenzylation to deliver 7a-l. The structures of the synthesized compounds were characterized using various physical and spectroscopic methods, including mp, UV, IR, NMR, MS and HRMS. The synthesized dibenzylated flavanones 6a-d, 6i and 7a were evaluated for their in vivo antiplasmodial activities against Plasmodium berghei infected mice. Molecular docking simulation and drug likeness properties of compounds 7a-l were assessed using AutoDock Vina and SwissADME, respectively.ResultsA series of chalcones 5a-r has been synthesized in yields ranging from 46 to 98%. Treatment of the chalcones 5a-r with NaOAc refluxing in EtOH afforded the dibenzylated pinocembrin analogs 6a-r with yields up to 54%. Deprotection of the dibenzylated pinocembrin analogs delivered the products 7a-l in yields ranging from 78 to 94%. The dibenzylated analogs of pinocembrin displayed percent inhibition of parastaemia in the range between 17.4 and 87.2% at 30 mg/kg body weight. The parastaemia inhibition of 87.2 and 55.6% was obtained on treatment of the infected mice with pinocembrin (7a) and 4’-chloro-5,7-dibenzylpinocembrin (6e), respectively. The mean survival times of those infected mice treated with these two compounds were beyond 14 days indicating that the samples suppressed P. berghei and reduced the overall pathogenic effect of the parasite. The molecular docking analysis of the chloro derivatives of pinocembrin revealed that compounds 7a-l show docking affinities ranging from – 8.1 to – 8.4 kcal/mol while it was -7.2 kcal/mol for chloroquine.ConclusionPinocembrin (7a) and 4’-chloro-5,7-dibenzyloxyflavanone (6e) displayed good antiplasmodial activity. The in silico docking simulation against P. falciparum dihydrofolate reductase-thymidylate synthase revealed that pinocembrin (7a) and its chloro analogs 7a-l showed better binding affinity compared with chloroquine that was used as a standard drug. This is in agreement with the drug-like properties of compounds 7a-l which fulfill Lipinski's rule of five with zero violations. Therefore, pinocembrin and its chloro analogs could serve as lead compounds for further antiplasmodial drug development.

Discovery of Cinnamylidene Derivative of Rhodanine with High Anthelmintic Activity against Rhabditis sp.

The treatment of parasitic infections requires the application of chemotherapy. In view of increasing resistance to currently in-use drugs, there is a constant need to search for new compounds with anthelmintic activity. A series of 16 cinnamylidene derivatives of rhodanine, including newly synthesized methoxy derivatives (1–11) and previously obtained chloro, nitro, and diethylamine derivatives (12–16), was investigated towards anthelmintic activity. Compounds (1–16) were evaluated against free-living nematodes of the genus Rhabditis sp. In the tested group of rhodanine derivatives, only compound 2 shows very high biological activity (LC50 = 0.93 µg/µL), which is higher than the reference drug albendazole (LC50 = 19.24 µg/µL). Crystal structures of two compounds, active 2 and inactive 4, were determined by the X-ray diffraction method to compare molecular geometry and search for differences responsible for observed biological activity/inactivity. Molecular modelling and selected physicochemical properties prediction were performed to assess the potential mechanism of action and applied in the search for an explanation as to why amongst all similar compounds only one is active. We can conclude that the tested compound 2 can be further investigated as a potential anthelmintic drug.

Emerging quinoline- and quinolone-based antibiotics in the light of epidemics.

Pandemics are large-scale outbreaks of infectious disease that can greatly increase morbidity and mortality all the globe. Since past 1990 till twentieth century, these infectious diseases have been major threat all over the globe associated with poor hygiene and sanitation. In light of these epidemics, researches have gained enormous rise in the developing the potential therapeutic treatment. Thus, revolutionized antibiotics have led to the near eradication of such ailments. Around 50million prescription of antibiotics written in US per year according to center for disease control and prevention (CDC) report. There is a wide range of antibiotics available which differ in their usage and their mechanism of action. Among these quinoline and quinolone class of antibiotics get attention as they show tremendous potential in fighting the epidemics. Quinoline and quinolone comprise of two rings along with substitutions at different positions which is synthetically obtained by structural modifications of quinine. Quinoline and quinolone antibiotics exhibit extensive activities approved by FDA in the treatment of the several ailments such as gastrointestinal infections, urinary tract infections, prostate inflammation, malaria, gonorrhea, skin infection, colorectal cancer, respiratory tract infections. These are active against both gram-negative and gram-positive bacteria. This basic core of quinoline and quinolone is vital due to its capability of targeting the pathogen causing disease and beneficial in treating the infectious disease. They inhibit the synthesis of nucleic acid of bacteria which results in the rupture of bacterial chromosome due to the interruption of enzymes such as DNA gyrase and topoisomerase IV. There are various quinoline and quinolone compounds that are synthetically derived by applying different synthesis approaches which show a wide range of pharmacological activities in several diseases. The most commonly used are fluoro, chloro, and hydroxychloro derivatives of quinoline and quinolone. These compounds are helpful in the treatment of numerous epidemics as a chief and combination therapy. These quinoline and quinolone pharmacophore fascinate the interest of researchers as they inhibit the entry of virus in host cell and cease its replication by blocking the host receptor glycosylation and proteolytic processing. They act as immune modulator by inhibiting autophagy and reduction of both lysosomal activity and production of cytokine. Therefore, quinoline and quinolone derivatives attain significance in area of research and treatment of various life-threatening epidemics such as SARS, Zika virus, Ebola virus, dengue, and COVID-19 (currently). In this chapter, the research and advancements of quinoline- and quinolone-based antibiotics in epidemic management are briefly discussed.

Computational Approaches for the Prediction of Environmental Transformation Products: Chlorination of Steroidal Enones.

There is growing interest in the fate and effects of transformation products generated from emerging pollutant classes, and new tools that help predict the products most likely to form will aid in risk assessment. Here, using a family of structurally related steroids (enones, dienones, and trienones), we evaluate the use of density functional theory to help predict products from reaction with chlorine, a common chemical disinfectant. For steroidal dienones (e.g., dienogest) and trienones (e.g., 17β-trenbolone), computational data support that reactions proceed through spontaneous C4 chlorination to yield 4-chloro derivatives for trienones and, after further reaction, 9,10-epoxide structures for dienones. For testosterone, a simple steroidal enone, in silico predictions suggest that C4 chlorination is still most likely, but slow at environmentally relevant conditions. Predictions were then assessed through laboratory chlorination reactions (0.5–5 mg Cl2/L) with product characterization via HRMS and NMR, which confirmed near exclusive 4-chloro and 9,10-epoxide products for most trienones and all dienones, respectively. Also consistent with computational expectations, testosterone was effectively unreactive at these same chlorine levels, although products consistent with in silico predictions were observed at higher concentrations (in excess of 500 mg Cl2/L). Although slight deviations from in silico predictions were observed for steroids with electron-rich substituents (e.g., C17 allyl-substituted altrenogest), this work highlights the potential for computational approaches to improve our understanding of transformation products generated from emerging pollutant classes.

Determination of the Absolute Configuration of Bioactive Indole-Containing Pyrazino[2,1-b]quinazoline-3,6-diones and Study of Their In Vitro Metabolic Profile.

In recent decades, fungi-derived naturally occurring quinazolines have emerged as potential drug candidates. Nevertheless, most studies are conducted for bioactivity assays, and little is known about their absorption, distribution, metabolism, and elimination (ADME) properties. To perform metabolic studies, the synthesis of the naturally occurring quinazolinone, fiscalin B (1), and its chloro derivative, 4-((1H-indol-3-yl)methyl)-8,10-dichloro-1-isobutyl-1,2-dihydro-6H-pyrazino[2,1-b]quinazoline-3,6(4H)-dione (2), disclosed as an antibacterial agent, was performed in a gram scale using a microwave-assisted polycondensation reaction with 22% and 17% yields, respectively. The structure of the non-natural (+)-fiscalin B was established, for the first time, by X-ray crystallography as (1R,4S)-1, and the absolute configuration of the naturally occurring fiscalin B (-)-1 was confirmed by comparison of its calculated and experimental electronic circular dichroism (ECD) spectra as (1S,4R)-1. in vitro metabolic studies were monitored for this class of natural products for the first time by ultra-high-performance liquid chromatography (UHPLC) coupled with high-resolution mass spectrometry (HRMS). The metabolic characteristics of 1 and 2 in human liver microsomes indicated hydration and hydroxylation mass changes introduced to the parent drugs.

Discovery of New Pyrazolopyridine, Furopyridine, and Pyridine Derivatives as CDK2 Inhibitors: Design, Synthesis, Docking Studies, and Anti-Proliferative Activity.

New pyridine, pyrazoloyridine, and furopyridine derivatives substituted with naphthyl and thienyl moieties were designed and synthesized starting from 6-(naphthalen-2-yl)-2-oxo-4-(thiophen-2-yl)-1,2-dihydropyridine-3-carbonitrile (1). The chloro, methoxy, cholroacetoxy, imidazolyl, azide, and arylamino derivatives were prepared to obtain the pyridine-−C2 functionalized derivatives. The derived pyrazolpyridine-N-glycosides were synthesized via heterocyclization of the C2-thioxopyridine derivative followed by glycosylation using glucose and galactose. The furopyridine derivative 14 and the tricyclic pyrido[3′,2′:4,5]furo[3,2-d]pyrimidine 15 were prepared via heterocyclization of the ester derivative followed by a reaction with formamide. The newly synthesized compounds were evaluated for their ability to in vitro inhibit the CDK2 enzyme. In addition, the cytotoxicity of the compounds was tested against four different human cancer cell lines (HCT-116, MCF-7, HepG2, and A549). The CDK2/cyclin A2 enzyme inhibitory results revealed that pyridone 1, 2-chloro-6-(naphthalen-2-yl)-4-(thiophen-2-yl)nicotinonitrile (4), 6-(naphthalen-2-yl)-4-(thiophen-2-yl)-1H-pyrazolo[3,4-b]pyridin-3-amine (8), S-(3-cyano-6-(naphthaen-2-yl)-4-(thiophen-2-yl)pyridin-2-yl) 2-chloroethanethioate (11), and ethyl 3-amino-6-(naphthalen-2-yl)-4-(thiophen-2-yl)furo[2,3-b]pyridine-2-carboxylate (14) are among the most active inhibitors with IC50 values of 0.57, 0.24, 0.65, 0.50, and 0.93 µM, respectively, compared to roscovitine (IC50 0.394 μM). Most compounds showed significant inhibition on different human cancer cell lines (HCT-116, MCF-7, HepG2, and A549) with IC50 ranges of 31.3–49.0, 19.3–55.5, 22.7–44.8, and 36.8–70.7 μM, respectively compared to doxorubicin (IC50 40.0, 64.8, 24.7 and 58.1 µM, respectively). Furthermore, a molecular docking study suggests that most of the target compounds have a similar binding mode as a reference compound in the active site of the CDK2 enzyme. The structural requirements controlling the CDK2 inhibitory activity were determined through the generation of a statistically significant 2D-QSAR model.

Cytotoxicity and pro-apoptosis activity of synthetic 1,3-thiazole incorporated phthalimide derivatives on cancer cells.

Objective(s):Cancer is the second important reason for death worldwide. In spite of advances in cancer treatment, however, survival of patients stays weak. Therefore, there is a critical need for advancement of new anticancer drugs. Regarding the hopeful biological activity of phthalimide derivatives, in this study, synthesis, cytotoxicity, and pro-apoptosis activity of eleven derivatives of thiazole bearing phthalimide structure were evaluated.Materials and Methods:First, target derivatives were synthesized. All synthesized compounds were characterized by spectroscopic methods. Cytotoxicity and pro-apoptosis activity of the synthesized compounds were evaluated in MDA-MB-468, PC-12, and MCF-7 cancer cell lines by MTT assay, caspase-3 activity, and TUNEL assay. Finally, expression of BAX, BCL-2, and FAS (as markers of apoptosis) was assessed by the RT-PCR procedure.Results:Among the eleven compounds, 5b (IC50 = 0.2±0.01 µM) was found to be the most potent derivative against MCF-7 cells. Also, Compound 5k and 5g showed strong cytotoxic activity against MDA-MB-468 and PC-12 cells with IC50 value of 0.6±0.04 µM and 0.43±0.06 µM, respectively. DNA fragmentation and activity of caspase-3 data suggest that cytotoxic activity of the compounds on cancer cells might be related to apoptosis. Also, RT-PCR of apoptosis markers indicated that these compounds induce apoptosis through the intrinsic pathway.Conclusion:Our findings suggest that para chloro derivative (5c) may be a promising agent for treatment of cancer cells by the targeted intrinsic pathway of apoptosis and could be used as a drug candidate for in vivo assessment in the treatment of cancer.

Chloro- and Trifluoromethyl Derivatives of a Pentagon-Fused C60: 1810C60Cl24, 1810C60Cl20, and 1810C60(CF3)14.

The carbon cage of Ih-C60, obeying the isolated-pentagon rule (IPR), can be transformed to the non-IPR D2h-1810C60 cage via two successive Stone-Wales rearrangements in the course of high-temperature chlorination of C60 with SbCl5. Two chloro derivatives, C2v-1810C60Cl24 and C2v-1810C60Cl20, have been isolated by high-performance liquid chromatography (HPLC). High-temperature trifluoromethylation of the chlorination products with CF3I, followed by HPLC separation, afforded a non-IPR CF3 derivative, Cs-1810C60(CF3)14. Structural elucidation of the isolated compounds revealed that all eight sites of pentagon-pentagon fusions on the carbon cage are preferentially occupied by Cl atoms or CF3 groups. According to density functional theory calculations, chloro and CF3 derivatives of 1810C60 are more stable than the isomeric derivatives of 1809C60 or IPR 1812C60, possessing respectively four or no sites of pentagon fusion in their carbon cages.

Triazole based copper(II) complexes: Synthesis, spectroscopic characterization, Density Function Theory study, and biomimicking of copper containing oxidase proteins

AbstractWithin the framework of the present study, a polydentate ligand with S and N donor sites along with its CuII‐based chelates were prepared and characterized. Elemental and thermal analyses, μeff and ΛM measurements as well as spectroscopy techniques including FT‐IR, electronic spectra, and EPR are the characterization tools. Computational chemistry calculations were applied to confirm the geometrical assignments of the penta and hexa coordinated perchlorato and chloro derivatives, respectively. Octahedral and trigonal bipyramidal stereochemistries were assigned for these copper(II) chelates. Powder X‐ray spectroscopy data were processed by Expo 2014 computer program for the structural illustration of one of the existing octahedral metal complexes. Biomimicking of copper(II) containing proteins phenoxazinone synthase and catechol oxidase was studied and the obtained results demonstrated promising oxidase‐like activity of the present CuII‐base complexes. Kinetic measurements were also performed to identify the potential catalytic pathways of the studied oxidation processes. The type of the counter‐anion included in the complexes significantly controls the structural features and the catalytic properties.

Development of adamantane scaffold containing 1,3,4-thiadiazole derivatives: Design, synthesis, anti-proliferative activity and molecular docking study targeting EGFR

A new series of 1,3,4-thiadiazolo-adamantane derivatives were synthesized through molecular hybridization approach, then used as starting material to synthesize chloro and cyano acetamide-thiadiazole derivatives 2, 3. The newly designed compounds 1–3 were treated with different reagents to design 5-adamantyl thiadiazole derivatives 4–17 and evaluate their in vitro anti-proliferative activity against three cancer cell lines (MCF-7, HepG-2 and A549). Doxorubicin was used as a positive control. The most promising compounds 5, 6, 10a, 10b, 14b, 14c, and 17 showed up-regulation for BAX and down-regulation of Bcl-2, these findings proved their role as hopeful apoptotic inducers. In addition, the inhibitory activity against both wild EGFRWT and mutant EGFRL858R-TK for these derivatives revealed that compounds 5, 14c, and 17 have IC50 value ranging from 85 nM to 71.5 nM against wild EGFRWT and 37.85–41.19 nM against the mutant type, Lapatinib was used as a reference standard with IC50 values of 31.8 nM and 39.53 nM, respectively. The most potent derivatives were subjected to further evaluation against double mutant EGFR L858R/T790M and showed good IC50 values between (0.27–0.78 nM) compared to Lapatinib (0.18 nM) and Erlotinib (0.21 nM). Among them, thiazolo-thiadiazole adamantane derivative 17 exhibited the strongest inhibitory activity to the EGFR. Molecular docking studies were performed inside the active site of EGFR (1M17), and binding energy scores ranged between (−19.19 to –22.07 Kcal/mol) compared to Erlotinib (−19.10 Kcal/mol). Furthermore, oral bioavailability beside some pharmacokinetics properties of these derivatives were also investigated in this research work.

Probing the Effect of Halogen Substituents (Br, Cl, and F) on the Non-covalent Interactions in 1-(Adamantan-1-yl)-3-arylthiourea Derivatives: A Theoretical Study.

The effect of halogen substituents (X = Br, Cl, and F) on the crystal packing and intra- and intermolecular interactions in four adamantane–thiourea hybrid derivatives is investigated using different theoretical tools. The bromo and chloro derivatives exhibit 3D isostructurality as evident from lattice parameters, molecular conformation, and crystal packing. The density functional theory study suggests that the molecular conformation of the parent (unsubstituted) and fluoro derivatives exhibits a stable low energy anti–syn conformation. In contrast, bromo and chloro derivatives adopt stable and relatively high energy minima on their potential energy surfaces. Hirshfeld surface analysis reveals the effect of halogen substituents on the intermolecular contacts. The halogen atoms mainly reduce the contribution of H···H contacts toward crystal packing. PIXEL energy analysis indicates the strong dimer formed by N–H···S hydrogen bonds in all four structures. It also revealed that a vast number of H···H contacts observed in different dimers of these structures either presented along with other conventional interactions or solely stabilize the dimeric topology. The topological parameters for intermolecular interactions in these structures suggest an intermediate bonding character between shared and closed-shell interactions for N–H···S hydrogen bonds in the parent and chloro derivatives. In contrast, the N–H···S hydrogen bond in other structures is of a closed-shell interaction. Among four derivatives, the fluoro derivative is weakly packed in the solid state based on the PIXEL method’s lattice energy calculation.

Effect of Flexible Chain on Mesomorphic Properties of Alkyloxy Substituted 4-Chloroazobenzene Liquid Crystals

Three rod-shaped alkyloxy substituted 4-chloroazobenzene liquid crystals, 1-(4-chlorophenyl)-2-[4- (alkyloxy)phenyl]diazene (hexayl, octyl and nonyl as flexible oxyalkyl chain) have been synthesized by diazotization of p-chloroaniline with phenol and subsequently performed etherification reaction with different alkyl bromides. The structures of the substituted 4-chloroazobenzene liquid crystals have been characterized by spectroscopic methods. The mesomorphic properties of the liquid crystals were examined by polarizing optical microscope (POM) and differential scanning calorimetry (DSC). All the oxyalkyl homologues of chloro substituted azobenzene showed enantiotropic smectic A (SmA) mesophase, which was understood clearly by the texture of the compounds employing polarizing optical microscope (POM) analysis. During heating scan in DSC analyses melting points, SmA-isotropic temperature and enthalphy changes associated with SmA-isotropic transition showed a remarkable impact on the spacer length of 4-chloro azobenzene derivatives.

In vitro anti-Trypanosoma cruzi activity enhancement of curcumin by its monoketone tetramethoxy analog diveratralacetone

Chagas disease is a tropical disease caused by the protozoan parasite Trypanosoma cruzi and currently affects millions of people worldwide. Curcumin (CUR), the major constituent of turmeric spice (dry powder of Curcuma longa L. plant rhizomes and roots), exhibits antiparasitic activity against protozoan parasites in vitro. However, because of its chemical instability, poor cellular uptake and limited bioavailability it is not suitable for clinical use. The objective of this study was to synthesize and evaluate in vitro CUR monoketone analog dibenzalacetone (DBA 1) and its non-phenolic, methoxy (2–4) and chloro (5) derivatives for better stability and bioavailability against T. cruzi. Diveratralacetone, the tetramethoxy DBA (DBA 3), was found to be the CUR analog with most enhanced activity against the amastigote forms of four strains of T. cruzi tested (Brazil, CA-I/72, Sylvio X10/4 and Sylvio X10/7) with 50% inhibitory concentration (IC50) < 10 μM (1.51–9.63 μM) and selectivity index (SI) > 10 (C2C12 non-infected mammalian cells). This was supplemented by time-course assessment of its anti-T. cruzi activity. DBA 1 and its dimethoxy (DBA 2) and hexamethoxy (DBA 4) derivatives were substantially less active. The inactivity of dichloro-DBA (DBA 5) was indicative of the important role played by oxygenated groups such as methoxy in the terminal aromatic rings in the DBA molecule, particularly at para position to form reactive oxygen species essential for anti-T. cruzi activity. Although the DBAs and CUR were toxic to infected mammalian cells in vitro, in a mouse model, both DBA 3 and CUR did not exhibit acute toxicity or mortality. These results justify further optimization and in vivo anti-T. cruzi activity evaluation of the inexpensive diveratralacetone for its potential use in treating Chagas disease, a neglected parasitic disease in economically challenged tropical countries.

Low-Temperature Alkaline Desorption of 2-Nitrophenol from Activated Carbon under Static Conditions

The nitro and chloro derivatives of phenols are xenobiotics. Active carbon (AC) is often used for the removal of such substances from natural, drinking, and waste waters. To a large extent, the economic feasibility of using AC depends on the method of their regeneration. Upon treating AC with an alkaline solution, the adsorbed phenols are ionized because of their weak acidic properties. The formed phenolate ions are desorbed from the carbon surface because of their lower adsorption energy and AC is regenerated. The study of low-temperature desorption of phenol derivatives is relevant for the development of technology for the regeneration of AC and biologically active carbon (BAC) directly in adsorbers that are made of modern composite (fiberglass) materials that are not designed for operating at temperatures higher than 40–50°C. The low-temperature alkaline desorption of 2-nitrophenol (NP) from equilibrium exhausted AC (reagent : AC ratio 10 : 1) is studied under laboratory static conditions in the mode of single-batch processing. The optimal alkali concentration (0.1 M) providing the maximum degree of sorbent recovery is determined. It is found that the degree of desorption of NP (5.7–45.6%) depends on the equilibrium concentration of sorbent saturation. The lower the equilibrium concentration at which AC exhausts, the lower the efficiency of alkaline regeneration of AC. The efficiency of NP desorption for operating temperatures of 15–35°C is verified. An increase in the temperature of reagent in the studied range does not lead to a substantial increase in the degree of desorption, but reduces the time required to establish the equilibrium of desorption by a factor of 1.5. More than 85–90% of equilibrium 2-nitrophenol desorbed from AC is removed in the first 4 to 8 h of treatment. Compared to microbial treatment, alkaline desorption allows one to achieve higher levels of AC regeneration (by 10–20%) and shorter processing times (100 times faster), which indicates the promising future for inclusion of this operation into bioadsorption technologies.

Trifluoromethyl derivatives of pentagon-fused C60: 1809C60(CF3)n (n = 10, 12, 14, 16).

The carbon cage of buckminsterfullerene Ih-C60, obeying the Isolated-Pentagon Rule (IPR), can be transformed to the non-IPR C2v-1809C60 cage by a single Stone-Wales rearrangement (SWR) in the course of high-temperature chlorination of C60 with SbCl5. The following high-temperature trifluoromethylation of the chlorination products with CF3I afforded non-IPR CF3 derivatives, 1809C60(CF3)n. X-ray diffraction studies of 1809C60(CF3)n (n = 10, 12, 14, 16) revealed that the sites of pentagon-pentagon fusions on the carbon cage are preferentially occupied by CF3 groups. The addition patterns of 1809C60(CF3)n and related 1809C60Cln are compared, demonstrating a prevailing role of pentagon-pentagon fusions in the stability and structural chemistry of these compounds. Further SWR skeletal transformations of 1809C60 are discussed and compared with the experimental data available.

Structural Studies of Giant Empty and Endohedral Fullerenes.

Structure elucidations of giant fullerenes composed of 100 or more carbon atoms are severely hampered by their extremely low yield, poor solubility and huge numbers of possible cage isomers. High-temperature exohedral chlorination followed by X-ray single crystal diffraction studies of the chloro derivatives offers a practical solution for structure elucidations of giant fullerenes. Various isomers of giant fullerenes have been determined by this method, specially, non-classical giant fullerenes containing heptagons generated by the skeletal transformations of carbon cages. Alternatively, giant fullerenes can be also stabilized by encapsulating metal atoms or clusters through intramolecular electron transfer from the encapsulated species to the outer fullerene cage. In this review, we present a comprehensive overview on synthesis, separation and structural elucidation of giant fullerenes. The isomer structures, chlorination patterns of a series of giant fullerenes C2n (2n = 100-108) and heptagon-containing non-classical fullerenes derived from giant fullerenes are summarized. On the other hand, giant endohedral fullerenes bearing different endohedral species are also discussed. At the end, we propose an outlook on the future development of giant fullerenes.

2,4-Dioxochroman Moiety Linked to 1,2,3-triazole Derivatives as Novel α-glucosidase Inhibitors: Synthesis, In vitro Biological Evaluation, and Docking Study

In this study, a novel series of 2,4-dioxochroman-1,2,3-triazole hybrids 8a-l was synthesized by click reaction. These compounds were screened against α-glucosidase through in vitro and in silico evaluations. All the synthesized hybrids exhibited excellent α-glucosidase inhibition in comparison to standard drug acarbose. Representatively, 3-((((1-(3,4-dichlorobenzyl)-1H-1,2,3-triazol-4-yl)methyl)amino)methylene)chroman-2,4- dione 8h with IC50 = 20.1 ± 1.5 μM against α-glucosidase, was 37-times more potent than acarbose. Enzyme kinetic study revealed that compound 8h was a competitive inhibitor against α-glucosidase. In silico docking study on chloro derivatives 8h, 8g, and 8i were also performed in the active site of α -glucosidase. Evaluations on obtained interaction modes and binding energies of these compounds confirmed the results obtained through in vitro α-glucosidase inhibition.