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Functionalised multi-walled carbon nanotubes (MWCNTs) are exclusively used in antibacterial activity due to their high aspect ratio and surface penetration characteristics. This study reports the synthesis of piperazine and dopamine functionalised MWCNTs to investigate antibacterial activity against strains like Staphylococcus aureus and Micrococcus luteus. MWCNTs were activated through acid oxidation and then refluxed at 75°C for 10 and 8 h in the presence of piperazine and dopamine, respectively. The functionalised MWCNTs were characterised by scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction and Raman spectroscopy. Moreover, functionalised MWCNTs were subjected to zone inhibition assay on agar plates. Results revealed the significant antibacterial activity against various bacteria up to 50%. Similarly, it was observed that the effect of different solvents, such as dimethyl formamide (DMF) and dimethyl sulfoxide (DMSO) was non-prevalent to the bacterial zone of inhibition. Such facile nano-modifications provide passage to nano-antibacterials for advanced studies.

Vanadium Pentoxide is considered as an intriguing material for several advanced technological applications such as supercapacitors, Lithium-ion batteries, photo-catalysis and optical waveguide. In this work, we have presented a facile and non-toxic method for the synthesis of Vanadium Pentoxide nanobelts. Considering the aforesaid motivations, we tuned the size of Vanadium Pentoxide nanobelts by simply varying the synthesis temperature. The XRD results confirm that the obtained phase is Vanadium Pentoxide with no impurities found within the experimental limitations. The analysis by Scanning Electron Microscopy (SEM) depicts that the diameter of nanobelts decreased from 52.7nm to 44.7nm with the increase in synthesis temperature within range 180oC-220 °C respectively. The UV–Vis-Spectrum shows that bandgap of nanobelts increased in the range 2.25eV-3eV with the increase in synthesis temperature within range 180oC-220 °C. For field emission measurements, the variation in field enhancement factor and turn-on voltage is also observed. These results indicate that by just varying a simple parameter one can tune the band gap and electronic properties of Vanadium Pentoxide nanobelts. These studies show that Vanadium Pentoxide nanobelts can be promising candidate for optoelectronic device.

A series of xanthene-based thiazoles was synthesized and characterized by different scpectroscopic methods, i.e. Proton nuclear magnetic resonance (H-1 NMR), carbon nuclear magnetic resonance (C-13 NMR), infrared spectroscopy, carbon hydrogen nitrogen analysis, and X-ray crystallography. The inhibition potencies of 18 newly synthesized thiazole derivatives were investigated on the activities of acetylcholinesterase (AChE), butyrylcholinesterase (BChE), alpha-amylase (alpha-Amy), and alpha-glycosidase (alpha-Gly) enzymes in accordance with their antidiabetic and anticholinesterase ability. The synthesized compounds have the highest inhibition potential against the enzymes at low nanomolar concentrations. Among the 18 newly synthesized molecules, 3b and 3p were superior to the known commercial inhibitors of the enzymes and have a much more effective inhibitory potential, with IC50: 2.37 and 1.07 nM for AChE, 0.98 and 0.59 nM for BChE, 56.47 and 61.34 nM for alpha-Gly, and 152.48 and 124.84 nM for alpha-Amy, respectively. Finally, the optimized 18 compounds were subjected to molecular docking to describe the interaction between thiazole derivatives and AChE, BChE, alpha-Amy, and alpha-Gly enzymes in which important interactions were monitored with amino acid residues of each target enzyme. WOS:000865845500001 Q2

Quinoxalin-2(1H)-one based design and synthesis produced several series of aldose reductase (ALR2) inhibitor candidates. In particular, phenolic structure was installed in the compounds for the combination of antioxidant activity and strengthening the ability to fight against diabetic complications. Most of the series 6 showed potent and selective effects on ALR2 inhibition with IC50 values in the range of 0.032-0.468 μM, and 2-(3-(2,4-dihydroxyphenyl)-7-fluoro-2-oxoquinoxalin-1(2H)-yl)acetic acid (6e) was the most active. More significantly, most of the series 8 revealed not only good activity in the ALR2 inhibition but also potent antioxidant activity, and 2-(3-(3-methoxy-4-hydroxystyryl)-2-oxoquinoxalin-1(2H)-yl)acetic acid (8d) was even as strong as the well-known antioxidant Trolox at a concentration of 100 μM, verifying the C3 p-hydroxystyryl side chain as the key structure for alleviating oxidative stress. These results therefore suggest an achievement of multifunctional ALR2 inhibitors having both potency for ALR2 inhibition and as antioxidants.

A novel, non-acid series of nitroquinoxalinone derivatives was synthesized and tested for their inhibitory activity against aldose reductase as targeting enzyme. All active compounds displayed an 8-nitro group, and showed significant activity in IC 50 values ranging from 1.54 to 18.17 μM. Among them 6,7-dichloro-5,8-dinitro-3-phenoxyquinoxalin-2(1 H )-one ( 7e ), exhibited the strongest aldose reductase activity with an IC 50 value of 1.54 μM and a good SAR (structure–activity relationship) profile.

A novel series of polyphosphazene-graft-polystyrene (PP-g-PS) copolymers were successfully prepared by atom transfer radical polymerization (ATRP) of styrene monomers and brominated poly(bis(4-methylphenoxy)phosphazene) macroinitiator. The graft density and the graft length could be regulated by changing the bromination degree of the macroinitiator and the ATRP reaction time, respectively. The PP-g-PS copolymers readily underwent a regioselective sulfonation reaction, which occurred preferentially at the polystyrene sites, producing the sulfonated PP-g-PS copolymers with a range of ion exchange capacities. The resulting sulfonated PP-g-PS membranes prepared by solution casting showed high water uptake, low water swelling and considerable proton conductivity. They also exhibited good oxidative stability and high resistance to methanol crossover. Morphological studies of the membranes by transmission electron microscopy showed clear nanophase-separated structures resulted from hydrophobic polyphosphazene backbone and hydrophilic polystyrene sulfonic acid segments, indicating the formation of proton transferring tunnels. Therefore, these sulfonated copolymers may be candidate materials for proton exchange membranes in direct methanol fuel cell (DMFC) applications.

Polyphosphazenes containing perfluoroalkyl sulfonic acids (PSA-P) were synthesized by the copper-catalyzed coupling reaction of poly[(4-bromophenoxy)(phenoxy)phosphazene] with potassium 1,1,2,2-tetrafluoro-2-(1,1,2,2-tetrafluoro-2-iodoethoxy) ethanesulfonate. Two synthetic protocols have been developed to obtain the polymers and 1, 10-phenanthroline was found benefit for improving the efficiency of the coupling reaction. The PSA-P membranes prepared by solution casting showed excellent thermal stability, oxidative stability and low swelling ratios. In addition, compared with the sulfonated poly[bis(phenoxy)phosphazene] membrane with similar IEC, the PSA-P membrane displayed significant superiority in proton conductivity, water resistance, oxidative and thermal stability, indicating that it is a good candidate for proton exchange membranes.

Sulfonyl group-containing compounds constitute an important class of therapeutical agents in medicinal chemistry presumably because of the tense chemical structure and functionality of the sulfonyl, which could not only form hydrogen bonding interactions with active site residues of biological targets but also, as incorporated into core ring structure, constrain the side chains and allowed their specific conformations that fit the active sites. This review focuses on sulfonamides and sulfones, which cover more than 40 series and are associated with at least 10 potential pharmaceutical targets in pathways of glucose metabolism and insulin signaling. A large number of such compounds have been reported as pharmaceuticals every year in the last decade. In particular, increasing studies suggest that sulfonamides and sulfones play a key role in the design of pharmaceutical agents with potential application for the treatment of diabetes and its complications. First, they are inhibitors of a variety of enzymes including 11β-hydroxysteroid dehydrogenase type 1, α- glucosidase, carnitine palmitoyltransferase and cytosolic phosphoenolpyruvate carboxykinase, and in turn involved in the regulation of the metabolism of glucose. In addition, they are active as activators of glucokinase and as antagonists of ghrelin receptors. These enzyme and receptors are tightly associated with the regulation of glucose metabolism and the improvement of insulin resistance. Secondly, sulfonamides and sulfones act in the insulin secretion. As agonists, they activate insulin receptor tyrosine kinase and thus increase insulin sensitivity. Moreover, they as inhibitors suppress protein tyrosine phosphatase 1B and dipeptidyl peptidase IV, and thus normalize the insulin signaling pathway. Finally, a number of sulfonamides and sulfones are inhibitors of aldose reductase, which have been linked to diabetic complications.

Due to the importance of aldose reductase (ALR2) as a potential drug target in the treatment of diabetic complications, there are increasing interests in design and synthesis of ALR2 inhibitors. Here, we prepared 1,2-benzothiazine 1,1-dioxide acetic acid derivatives and investigated their inhibition activity. Most of these derivatives were found to be active with IC(50) values ranging from 0.11 μM to 10.42 μM, and compound 8d, 2-[2-(4-bromo-2-fluorobenzyl)-1,1-dioxido-2H-1,2-benzothiazin-4(3H)-ylidene]acetic acid, showed the most potent inhibition activity. Further, SAR and docking studies suggest that in comparison with the α,β-unsaturated derivatives, the saturated carboxylic acid derivatives had a greater binding affinity with the enzyme and thus an enhanced inhibition activity. Therefore, development of more powerful ARIs based on benzothiazine 1,1-dioxide by stereo-controlled synthesis could be expected.

Dimorphamides A–C (1–3, resp.), three new polyphenolic amides, have been isolated from the BuOH-soluble fraction of the whole plant of Atriplex dimorphostagia, along with two known compounds, thymidine and N-[(E)-feruloyl]tyramine. Their structures have been determined on the basis of spectral studies.

A novel series of (1,2-benzothiazin-4-yl)acetic acid enantiomers was prepared by chiral resolution, and their absolute configurations were determined using the PGME method. The biological evaluation of the racemate and single enantiomers has shown a remarkable difference for the aldose reductase inhibitory activity and selectivity. The (R)-(−)-enantiomer exhibited the strongest aldose reductase activity with an IC50 value of 0.120 μM, which was 35 times more active than the S-(+)-enantiomer. Thus, the stereocenter at the C4 position of this scaffold was shown to have a major impact on the activity and selectivity.

A copper catalyst system for the asymmetric 1,4-hydrosilylation of the α,β-unsaturated carboxylate class was developed by which synthesis of (+)- and (-)-enantiomers of 1,2-benzothiazine-1,1-dioxide acetates has been achieved with a good yield and an excellent level of enantioselectivity. A comparative structure-activity relationship study yielded the following order of aldose reductase inhibition activity: (-)-enantiomers > racemic > (+)-enantiomers. Further, a molecular docking study suggested that the (-)-enantiomer had significant binding affinity and thus increased inhibition activity.

In the title phosphonate, C19H21O9P, the dihedral angle between the benzene rings is 63.33 (3)°, and the P atom has a distorted tetrahedral geometry, with angles in the range 101.30 (6)–120.38 (6)°. No significant intermolecular interactions are observed in the crystal structure, and π–π interactions between symmetry-related benzene rings are beyond 4 Å.

In the title phospho­nate, C19H21O9P, the dihedral angle between the benzene rings is 63.33 (3)°, and the P atom has a distorted tetra­hedral geometry, with angles in the range 101.30 (6)–120.38 (6)°. No significant inter­molecular inter­actions are observed in the crystal structure, and π–π inter­actions between symmetry-related benzene rings are beyond 4 Å.

Novel quinoxalinone derivatives were synthesized and tested for their inhibitory activity against aldose reductase. Among them, N1-acetate derivatives had significant activity in a range of IC 50 values from low micromolar to submicromolar, and compound 15a bearing a C3-phenethyl side chain was identified as the most potent inhibitor with an IC 50 value of 0.143 μM. The structure–activity studies suggested that both C3-phenethyl and C6-NO 2 groups play an important role in enhancing the activity and selectivity of the quinoxalinone based inhibitors.

The development and progression of chronic complications in diabetic patients, such as retinopathy, nephropathy, neuropathy, cataracts, and stroke, are related to the activation and/or overexpression of aldose reductase (ALR2), which is a member of the aldo-keto reductase superfamily. A structure-activity relationship study focused on the C7 position of 1,2,4-benzothiadiazine-1,1-dioxide derivatives was pursued in an attempt to discover ALR2 inhibitors with enhanced potency and selectivity. These studies led to a series of new C7-substituted compounds, which were evaluated for their inhibitory activity against ALR2; they exhibited IC(50) values in the range of 2.80-45.13 nM. Two compounds with a C7-dimethylcarbamoyl and a C7-diethylcarbamoyl substituent, respectively, were found to be the most active and presented excellent selectivity for ALR2 over aldehyde reductase (ALR1). The structure-activity relationship analyses and molecular modeling studies presented herein highlight the importance of hydrophobic and bulky groups at the C7 position for inhibitory activity and selectivity toward ALR2.

A novel and facile synthesis of quinoxalinone derivatives was developed in which a wide range of 3-chloroquinoxalin-2(1H)-ones as key intermediates can be generated chemo- and regioselectively in good yields from corresponding quinoxaline-2,3(1H,4H)-diones. This new protocol is arguably superior, as it allows the design and preparation of a variety of bioactive quinoxaline-based compounds, which are particularly effective in the treatment of diabetes and its complications. Through this procedure, a new class of quinoxalinone-based aldose reductase inhibitors were synthesized successfully. Most of the inhibitors, with an N1-acetic acid head group and a substituted C3-phenoxy side chain, proved to be potent and selective. Their IC(50) values ranged from 11.4 to 74.8 nM. Among them, 2-(3-(4-bromophenoxy)-7-fluoro-2-oxoquinoxalin-1(2H)-yl)acetic acid and 2-(6-bromo-3-(4-bromophenoxy)-2-oxoquinoxalin-1(2H)-yl)acetic acid were the most active. Structure-activity relationship and molecular docking studies highlighted the importance of the ether spacer in the C3-phenoxy side chains, and provided clear guidance on the contribution of substitutions both at the core structure and the side chain to activity.

A series of pyrido[2,3-e]-[1,2,4]-thiadiazine 1,1-dioxide acetic acid derivatives were synthesized and tested for their inhibitory activity against aldose reductase (ALR2). These derivatives were found to be potent aldose reductase inhibitors with IC50 values ranging from 0.038 μM to 11.29 μM. Most but not all of them showed a strong ALR2 inhibition activity and significant selectivity, which were further supported by docking studies. Of these inhibitors, compound 7d exhibited highest inhibition activity. Structure-activity relationship studies indicate the requirement of N2-benzyl group with electron-withdrawing substituents and N4-acetic acid group in the pyridothiadiazine scaffold.

In the title compound, C17H12F3NO4S, the heterocyclic thiazine ring adopts a half-chair conformation and the dihedral angle between the benzene rings is 43.28 (9)°. The α,β-unsaturated C=C group is inclined at an angle of 21.0 (3)° to the benzene ring of the benzothiazine moiety. In the crystal, inversion dimers linked by pairs of carboxylic acid O—H...O hydrogen bonds generateR22(8) loops. Each of the F atoms accepts a Ca—H...F (a = aromatic) hydrogen bond from an adjacent molecule, resulting in (001) sheets.

α,β- and β,γ-unsaturated carboxylate isomers of 1,2-benzothiazine-1,1-dioxide were selectively synthesized via the Wittig olefination reaction under various temperature conditions. At 40 °C, α,β-unsaturated esters with high Z-stereoselectivity (83–87%) were formed, while β,γ-unsaturated esters formed preferentially with moderate to excellent regioselectivity at 100–120 °C (77–96%). The acid isomers were found to inhibit aldose reductase in order of activity β,γ-unsaturated > Z-α,β-unsaturated > E-α,β-unsaturated isomers. The β,γ-unsaturated isomer 7b, 2-[2-(4-bromo-2-fluorobenzyl)-1,1-dioxido-2H-1,2-benzothiazin-4(3H)-ylidene]acetic acid, exhibited the most potent inhibition activity, with an IC50 value of 0.057 μM. This was further supported by docking studies.