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A new UV‐active indole‐pyrazole extended π‐system (probe A) that displays a large bathochromic shift (∼325 nm) when it interacts only with Co2+ and not with other transition metal ions, is presented. The increase in the intensity of new transitions at 592 and 684 nm due to A−Co2+−Cl2.H2O complex formation occurs at the expense of the transition at 358 nm arising from the probe A, and thereby offers a ratiometric method for detection of Co2+ present in aqueous samples. The ratiometric method sets the detection limit for Co2+ at 0.404×10−6 M and 0.337×10−6 M, when calculated for the transitions at 592 and 684 nm, respectively. The corresponding association constants are 4.041×105 M−1 at 592 nm, and 3.617×105 M−1 at 684 nm. Job plot and ESI‐MS data confirmed the 1 : 1 stoichiometry of A−Co2+−Cl2.H2O complex. The mode of interaction between the probe A and Co2+ is explained in terms of conformational isomerization and chelation, using 1H NMR method and DFT calculations. Other metal ions commonly found in the environment do not seem to interfere in the selective determination of Co2+ ions. Suitability of probe A in the detection of Co2+ at concentrations less than 1.7 μM (recommended level of Co2+ ions by US‐EPA) is also demonstrated using water samples collected from the environment. Test kits suitable for routine on‐site analysis are also developed. [ABSTRACT FROM AUTHOR]

Abstract: A new series of bis- and tris-spirooxindole derivatives have been synthesized by controlling the molar equivalent of in situ generated azomethine ylides in [3+2]-cycloaddition reactions with dipolarophiles. The structural elucidation on the basis of IR, 1H NMR, 13C NMR, and mass spectral data of these compounds established the highly chemoselective and regioselective formation of spirooxindole derivatives. Single crystal X-ray analysis of compound 4g and 2D NMR analysis of compound 5a confirmed the structures of bis- and tris-spirooxindole derivatives. [Copyright &y& Elsevier]

Highlights: [•] Resveratrol acts as a reducing agent in the synthesis of gold nanoparticles. [•] Capping of gold nanoparticles by resveratrol prevents self-agglomeration. [•] Resveratrol capping permits loading of doxorubicin onto gold nanoparticles. [ • ] Doxorubicin loaded gold nanoparticles show enhanced anticancer activity in vitro. [Copyright &y& Elsevier]

A series of pyridopyridazin-3(2H)-one derivatives was synthesized in two facile steps. Mannich-type three-component condensa-tion afforded the 2,6-diaryl piperidin-4-one derivatives, which underwent intramolecular cyclization in the presence of hydrazine or phenylhydrazine to yield the corresponding pyridopyridazin-3(2H)-one derivatives. All the derivatives of pyridopyridazin-3(2H)-one, except 3e and 3f, showed moderate activity against human breast adenocarcinoma (MCF-7) cells. The higher degree of inhibition of MCF-7 cell proliferation shown by 2a-2f indicates the significance of the amide proton in pyridopyridazin-3(2H)-one derivatives. [ABSTRACT FROM AUTHOR]

A highly selective and efficient single molecular FRET based sensor has been developed for the ratiometric detection of Fe3+ in aqueous samples and live cells. [ABSTRACT FROM AUTHOR]

Abstract: The regioselective synthesis of a series of novel dispiropyrrolidines and dispiropyrrolizidines has been accomplished through intermolecular 1,3-dipolar cycloaddition of azomethine ylides obtained from 1,2-diones like isatin and acenaphthenequinone with acenaphthenone-2-ylidine ketone dipolarophiles in methanol under reflux conditions. [Copyright &y& Elsevier]

Abstract: The size of the chelating ligand and nature of coordinating entities of the chelating moiety have been exploited to synthesize four rhodamine based chemosensors for selective recognition of metal ions. A triazole appended colorless chemosensor turns to pink upon complex formation only with Cu2+ ions even in the presence of other competing metal ions at physiological pH, and enables naked-eye detection and imaging of live fibroblast cells exposed to Cu2+ ions. [Copyright &y& Elsevier]

Abstract: A bis-rhodamine based fluorescent chemosensor for naked-eye detection of Cu2+ with enhanced sensitivity as compared to mono-rhodamine derivative has been synthesized, and its selectivity for Cu2+ in the presence of other competitive metal ions (Li+, Na+, K+, Cs+, Mg2+, Ca2+, Sr2+, Cr3+, Mn2+, Fe2+, Fe3+, Co2+, Ni2+, Zn2+, Cd2+, Hg2+, and Pb2+), and application in bio-imaging are demonstrated. [Copyright &y& Elsevier]

In a minimalist design approach, a synthetic peptide MSI-367 [(KFAKKFA)3-NH3] was designed and synthesized with the objective of generating cell-selective nonlytic peptides, which have a significant bearing on cell targeting. The peptide exhibited potent activity against both bacteria and fungi, but no toxicity to human cells at micromolar concentrations. Bacterial versus human cell membrane selectivity of the peptide was determined via membrane permeabilization assays. Circular dichroism investigations revealed the intrinsic helix propensity of the peptide, β-turn structure in aqueous buffer and extended and turn conformations upon binding to lipid vesicles. Differential scanning calorimetry experiments with 1,2-dipalmitoleoyl-sn-glycero-3-phosphatidylcthanolamine bilayers indicated the induction of positive curvature strain and repression of the fluid lamellar to inverted hexagonal phase transition by MSI-367. Results of isothermal titration calorimetry (ITC) experiments suggested the possibility of formation of specific lipid-peptide complexes leading to aggregation. ²H nuclear magnetic resonance (NM R) of deuterated 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) multilamellar vesicles confirmed the limited effect of the membrane-embedded peptide at the lipid-water interface. 31P NMR data indicated changes in the lipid headgroup orientation of POPC, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylglycerol, and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylethanolamine lipid bilayers upon peptide binding. Membrane-embedded and membrane-inserted states of the peptide were observed via sum frequency generation vibrational spectroscopy. Circular dichroism, ITC, and 31PNM R data for Escherichia coil lipids agree with the hypothesis that strong electrostatic lipid-peptide interactions embrace the peptide at the lipid-water interface and provide the basis for bacterial cell selectivity. [ABSTRACT FROM AUTHOR]

Tachyplesin I is a cyclic β-sheet antimicrobial peptide isolated from the hemocytes of Tachypleus tridentatus. The four cysteine residues in tachyplesin I play a structural role in imparting amphipathicity to the peptide which has been shown to be essential for its activity. We investigated the role of amphipathicity using an analogue of tachyplesin I (TP-I), CDT (KWFRVYRGIYRRR-NH2), in which all four cysteines were deleted. Like TP-I, CDT shows antimicrobial activity and disrupts Escherichia coli outer membrane and model membranes mimicking bacterial inner membranes at micromolar concentrations. The CDT peptide does not cause hemolysis up to 200 µg/mL while TP-I showed about 10% hemolysis at 100 µg/mL and about 25% hemolysis at 150 µg/mL. Peptide-into-lipid titrations under isothermal conditions reveal that the interaction of CDT with lipid membranes is an enthalpy-driven process. Binding assays performed using fluorometry demonstrate that the peptide CDT binds and inserts into only negatively charged membranes. The peptide-induced thermotropic phase transition of MLVs formed of DMPC and the DMPC/DMPG (7:3) mixture suggests specific lipid-peptide interactions. The circular dichroism study shows that the peptide exists as an unordered structure in an aqueous buffer and adopts a more ordered β-structure upon binding to negatively charged membrane. The NMR data suggest that CDT binding to negatively charged bilayers induces a change in the lipid headgroup conformation with the lipid headgroup moving out of the bilayer surface toward the water phase, and therefore, a barrel stave mechanism of membrane disruption is unlikely as the peptide is located near the headgroup region of lipids. The lamellar phase 31P chemical shift spectra observed at various concentrations of the peptide in bilayers suggest that the peptide may function neither via fragmentation of bilayers nor by promoting nonlamellar structures. NMR and fluorescence data suggest that the presence of cholesterol inhibits the peptide binding to the bilayers. These properties help to explain that cysteine residues may not contribute to antimicrobial activity and that the loss of hemolytic activity is due to lack of hydrophobicity and amphipathicity. [ABSTRACT FROM AUTHOR]

Abstract: A 15-residue peptide dimer G15 derived from the cell lytic protein granulysin has been shown to exert potent activity against microbes, including E. coli, but not against human Jurkat cells [Z. Wang, E. Choice, A. Kaspar, D. Hanson, S. Okada, S.C. Lyu, A.M. Krensky, C. Clayberger, Bactericidal and tumoricidal activities of synthetic peptides derived from granulysin. J. Immunol. 165 (2000) 1486–1490]. We investigated the target membrane selectivity of G15 using fluorescence, circular dichroism and 31P NMR methods. The ANS uptake assay shows that the extent of E. coli outer membrane disruption depends on G15 concentration. 31P NMR spectra obtained from E. coli total lipid bilayers incorporated with G15 show disruption of lipid bilayers. Fluorescence binding studies on the interaction of G15 with synthetic liposomes formed of E. coli lipids suggest a tight binding of the peptide at the membrane interface. The peptide also binds to negatively charged POPC/POPG (3:1) lipid vesicles but fails to insert deep into the membrane interior. These results are supported by the peptide-induced changes in the measured isotropic chemical shift and T1 values of POPG in 3:1 POPC:POPG multilamellar vesicles while neither a non-lamellar phase nor a fragmentation of bilayers was observed from NMR studies. The circular dichroism studies reveal that the peptide exists as a random coil in solution but folds into a less ordered conformation upon binding to POPC/POPG (3:1) vesicles. However, G15 does not bind to lipid vesicles made of POPC/POPG/Chl (9:1:1) mixture, mimicking tumor cell membrane. These results explain the susceptibility of E. coli and the resistance of human Jurkat cells to G15, and may have implications in designing membrane-selective therapeutic agents. [Copyright &y& Elsevier]

Abstract: Subtilosin A is an antimicrobial peptide produced by the soil bacterium Bacillus subtilis that possesses bactericidal activity against a diverse range of bacteria, including Listeria monocytogenes. Recent structural studies have found that subtilosin A is posttranslationally modified in a unique way, placing it in a new class of bacteriocins. In this study, in order to understand the mechanism of membrane-disruption by subtilosin A, the interaction of the peptide with model phospholipid bilayers is characterized using fluorescence, solid-state NMR and differential scanning calorimetry (DSC) experiments. Our results in this study show that subtilosin A interacts with the lipid head group region of bilayer membranes in a concentration dependent manner. Fluorescence experiments reveal the interaction of subtilosin A with small unilamellar vesicles (SUVs) composed of POPC, POPG and E. coli total lipids, and that at least one edge of the molecule is buried in membrane bilayers. At high concentrations, it induces leakage from SUVs of POPC and POPE/POPG (7:3) mixture. 15N solid-state NMR data suggests that the cyclic peptide is partially inserted into bilayers, which is in agreement with the fluorescence data. 31P and 2H NMR experiments and DSC data support the hypothesis that subtilosin A adopts a partially buried orientation in lipid bilayers, by showing that it induces a conformational change in the lipid headgroup and disordering in the hydrophobic region of bilayers. These results suggest that the lipid perturbation observed in this study may be one of the consequences of subtilosin A binding to lipid bilayers, which results in membrane permeabilization at high peptide concentrations. [Copyright &y& Elsevier]

Abstract: Lipopeptide MSI-843 consisting of the nonstandard amino acid ornithine (Oct–OOLLOOLOOL–NH2) was designed with an objective towards generating non-lytic short antimicrobial peptides, which can have significant pharmaceutical applications. Octanoic acid was coupled to the N-terminus of the peptide to increase the overall hydrophobicity of the peptide. MSI-843 shows activity against bacteria and fungi at micromolar concentrations. It permeabilizes the outer membrane of Gram-negative bacterium and a model membrane mimicking bacterial inner membrane. Circular dichroism investigations demonstrate that the peptide adopts α-helical conformation upon binding to lipid membranes. Isothermal titration calorimetry studies suggest that the peptide binding to membranes results in exothermic heat of reaction, which arises from helix formation and membrane insertion of the peptide. 2H NMR of deuterated-POPC multilamellar vesicles shows the peptide-induced disorder in the hydrophobic core of bilayers. 31P NMR data indicate changes in the lipid head group orientation of POPC, POPG and Escherichia colitotal lipid bilayers upon peptide binding. Results from 31P NMR and dye leakage experiments suggest that the peptide selectively interacts with anionic bilayers at low concentrations (up to 5 mol%). Differential scanning calorimetry experiments on DiPOPE bilayers and 31P NMR data from E.coli total lipid multilamellar vesicles indicate that MSI-843 increases the fluid lamellar to inverted hexagonal phase transition temperature of bilayers by inducing positive curvature strain. Combination of all these data suggests the formation of a lipid–peptide complex resulting in a transient pore as a plausible mechanism for the membrane permeabilization and antimicrobial activity of the lipopeptide MSI-843. [Copyright &y& Elsevier]

Abstract: The use of two derivatives of 2-methoxy-4-methylsulfinylbenzyl alcohol is demonstrated as a safety-catch protecting group and linker for solid-phase peptide synthesis. The protecting group and linker are stable to TFA and are readily removed under reductive acidolytic conditions. [Copyright &y& Elsevier]

In the title imidazo[1,2-a]pyridine derivatives, N-tert-butyl-2-(4-meth­oxy­phen­yl)-5-methyl­imidazo[1,2-a]pyridin-3-amine, C19H23N3O, (I), and N-tert-butyl-2-[4-(di­methyl­amino)­phen­yl]imidazo[1,2-a]pyridin-3-amine, C19H24N4, (II), the 4-meth­oxy­phenyl ring in (I) and the 4-(di­methyl­amino)­phenyl ring in (II) are inclined to the respective imidazole rings by 26.69 (9) and 31.35 (10)°. In the crystal of (I), mol­ecules are linked by N—H· · ·N hydrogen bonds, forming chains propagating along the [001] direction. The chains are linked by C—H· · ·π inter­actions, forming layers parallel to the (010) plane. In (II), the crystal packing also features N—H· · ·N hydrogen bonds, which together with C—H· · ·N hydrogen bonds link mol­ecules to form chains propagating along the c-axis direction. The chains are linked by C—H· · ·π inter­actions to form layers parallel to the (100) plane. Inversion-related layers are linked by offset π–π inter­actions [inter­centroid distance = 3.577 (1) Å]. The inter­molecular inter­actions of both compounds were analyzed using Hirshfeld surface analysis and two-dimensional fingerprint plots. [ABSTRACT FROM AUTHOR]

Imidazo[1,2-a]pyridine derivatives have excellent potential for chelation with transition metal ions. Two new imidazo[1,2-a]pyridine-8-carboxylates were synthesized and characterized by 1H NMR, 13C NMR, HRMS, and single crystal-XRD techniques. Methyl carboxylate (probe 1) turns on fluorescence upon coordination with Zn2+, while sodium carboxylate (probe 2) turns off its fluorescence upon coordination with Co2+ or Cu2+ ions present in aqueous acetonitrile medium. 13C NMR study revealed that the change in metal ion specific binding was due to the involvement of carboxylate anion in complex formation with Co2+ or Cu2+ ions. The carboxylate anion at 8-position also enhanced the sensitivity of detection of probe 2 by an order of magnitude (detection limits: 3.804 × 10–7 M, probe 1/Zn2+; 0.420 × 10–7 M, probe 2/Co2+ and 0.304 × 10–7 M, probe 2/Cu2+). The detection limits of probes 1 and 2 comply well with the World Health Organization (WHO) and US Environmental Protection Agency (US-EPA) guidelines for detection of heavy metal ions present in drinking water and ground water. Both the probes form a 1:1 complex with Zn2+, Co2+ or Cu2+, and the stoichiometry was verified by Job plot and ESI-mass analysis. The sensing mechanism is explained using 13C NMR experiments, ESI-mass analytical data and theoretical DFT calculations. The suitability of probes 1 and 2 for on-site detection and quantitative determination of Zn2+, Co2+ and Cu2+ ions present in biological, environmental and industrial samples is demonstrated. In addition, both 1 and 2 are used for detection of intracellular contamination of Zn2+, Co2+ or Cu2+ ions in onion epidermal cells. [ABSTRACT FROM AUTHOR]

Three classes of densely functionalized dispirocyclopentaneoxindoles containing multiple stereocenters are synthesized via base-promoted domino- and self-domino reactions. [ABSTRACT FROM AUTHOR]

The article presents chemical equations for the article "Regioselective Synthesis of Novel Dispiropyrrolidine and Dispiropyrrolizidine Oxindole Derivatives via Azomethine Ylide Specific [3 + 2]-Cycloaddition" by S. Lanka and others, published in the periodical "RSC Advances" in 2014.

Density functional theoretical calculations predicted non‐coplanar twisted geometry for two new imidazo[1,2‐a]pyridine derivatives, Imp and ImBt. Analysis of single‐crystal of Imp asserted the non‐coplanar twisted geometry, which is implicated in aggregation induced emission (AIE) of small aromatic molecules. Universal quenching by water was observed in aqueous THF solutions of Imp and ImBt, but they showed AIE effect when the water content was more than 80 %. Non‐fluorescent solutions of Imp and ImBt in THF‐water (7 : 3 v/v) mixture turned fluorescent on addition of specific metal ions prompting their potential to be explored for turn‐on sensor applications. While ImBt showed AIE response to Cd2+, Hg2+ and Al3+, Imp displayed AIE effect only to Cd2+ ions, under identical conditions. Absence of interference from common metal ions (including Hg2+ and Al3+) led to selective formation of Imp‐CdCl2 (1 : 1) complex, which offered the limit of detection of Cd2+ to be 19.2 μM. The observed selectivity for Cd2+ permitted the use of Imp in the imaging of live Rhizoctonia oryze contaminated with Cd2+ ions. [ABSTRACT FROM AUTHOR]

A Lewis acid catalyzed domino reactioncascades through azide–alkenecycloaddition, rearrangement, aziridine ring opening, and azomethinecycloaddition with a parent dipolarophile, resulting in 3,3′-pyrrolidinyldispirooxindolescontaining four contiguous chiral stereocenters with two contiguousquaternary spirostereocenters. [ABSTRACT FROM AUTHOR]

[Display omitted] • A simple single step multicomponent ugi type reaction was carried out to yield N-(tert-butyl)-2-(furan-2-yl)imidazo[1,2- a ]pyridine-3-amine (TBFIPA). • The synthesized TBFIPA was characterized using 1H NMR, 13C NMR and HRMS spectroscopic methods. • The selective & sensitive detection was identified using hypsochromic shift (lab : 335nm → 285nm) & fluorescence quenching. • The proposed mechanism is evident from Job plot, 1H NMR titration, ESI-MS data and theoretical DFT calculation. • The Cr3+ ion-selective TBFIPA was successfully applied in the design of a user-friendly silica-based portable test kits. • Also, the fluorescence quenching ability of TBFIPA in presence of Cr3+ ions are validated by imaging onion epidermal cells. • Real samples contaminated with Cr3+ ions were identified using TBFIPA with an appropriated relative error percentage. A simple single step one pot multicomponent reaction was performed to synthesize N-(tert -butyl)-2-(furan-2-yl)imidazo[1,2- a ]pyridine-3-amine (TBFIPA). The synthesized TBFIPA was subjected to library of cations to study its ability for selective and sensitive detection of specific metal ions. Selective detection of chromium ions by TBFIPA were found from the significant hypsochromic shift (335 nm → 285 nm) in the UV–Visible spectra. The fluorescent TBFIPA displays complete quenching of fluorescence under UV lamp (365 nm) only in the presence of chromium without the interference of common metal ions. Binding constant (k a) obtained from Benesi-Hildebrand plot is 0.21 × 105 M−1, limit of detection (LOD) and limit of quantification (LOQ) of TBFIPA toward Cr3+ ions are 4.70 × 10−7 M and 1.56 × 10−7 M, respectively. The mechanism proposed during complex formation were supported by stoichiometric Job continuous variation plot, 1H NMR titration and ESI-MS spectroscopic data. All the experimental confirmation for complex formation were corroborated with theoretical DFT studies optimized using RB3LYP/6-31G(d) basis set. The selectivity and sensitivity of TBFIPA toward Cr3+ ions are found suitable to design a user-friendly silica based portable test kit. Alongside, TBFIPA was successfully utilized for imaging onion epidermal cells. Furthermore, the results obtained for biological, environmental, and industrial samples provided solid evidence to estimate chromium ions using TBFIPA in these real samples. [ABSTRACT FROM AUTHOR]

Incorporation of the triazolyl moiety modulates the basicity and effective size of the chelating ring, changes the stoichiometry in complex formation and thereby imparts Cu2+ ion selectivity. [ABSTRACT FROM AUTHOR]

Abstract: 5,5-Acetamidomethyl-5-methylimidazolidine-2,4-dione shows antimicrobial activity against bacteria at millimolar concentrations well above its critical micellar concentration (cmc). Two-dimensional surface properties were investigated using Langmuir Film Balance to understand the membrane-active nature and nanomaterial behavior of this hydantoin derivative. Hydantoin forms an expanded nanofilm at air–water interface. The maximum limiting surface area (A 0) and collapse pressure (π c ) are dependent on hydantoin concentration. Hydantoin undergoes a change in orientation at the interface, in the pressure region 2.5 and 7.5mNm−1, corresponding to surface areas 51–15 and 41–12Å2 molecule−1, respectively. A large collapse pressure (π c ) in LB film indicates a role for hydrophobic interactions in the self-assembly of hydantoin. Surface areas computed using Connolly method, are in good agreement with the experimental results. Monolayer studies suggest a dispersed state for hydantoin when its concentration is below cmc, suggesting a mechanism for the observed bacteriostatic activity of hydantoin. In the present study, it has been found for the first time that the minimum inhibitory concentration (MIC) of the hydantoin is very close to its cmc. [Copyright &y& Elsevier]

Magainins are antimicrobial peptides that selectively disrupt bacterial cell membranes. In an effort to determine the propensity for oligomerization of specific highly active magainin analogues in membrane mimetic systems, we studied the structures and lipid interactions of two synthetic variants of magainins (MSI-78 and MSI-594) originally designed by Genaera Corp. Using NMR experiments on these peptides solubilized in dodecyiphosphocholine (DPC) micelles, we found that the first analogue, MSI-78, forms an antiparallel dimer with a "phenylalanine zipper" holding together two highly helical protomers, whereas the second analogue, MSI-594, whose phenylalanines 12 and 16 were changed into glycine and valine, respectively, does not dimerize under our experimental conditions. In addition, magic angle spinning solid-state NMR experiments carried out on multilamellar vesicles were used to corroborate the helical conformation of the peptides found in detergent micelles and support the existence of a mure compact structure for MSI-78 and a pronounced conformational heterogeneity for MSI-594. Since magainin activity is modulated by oligomerization within the membrane bilayers, this study represents a step forward in understanding the role of self-association in determining magainin function. [ABSTRACT FROM AUTHOR]

Heterocyclic compounds play an important role in organic chemistry due to their wide variety of applications in pharmacy, veterinary science and agriculture. Many significant heterocycles having application in medicinal chemistry and material science has nitrogen fused heterocyclic imidazole ring as common structural motifs. Imidazoles are one among the heterocyclic compounds which show significant pharmacological properties. Due to the importance of imidazole derivatives two compounds2-(5-(3-(tert-butylamino)imidazo[1,2-a]pyridin-2-yl)thiophen-2-yl)-6-fluorobenzaldehyde and Methyl-3-(tert-butylamino)-2-(pyridin-2-yl)imidazo[1,2-a]pyridine-8-carboxylate has been synthesized, and the structures were confirmed by single crystal X-ray diffraction studies. In the crystals, molecules are linked by intermolecular C-H…S, N-H…N, and C-H…N hydrogen bonds. Both compounds exhibits π..π, and C-H…π interactions. Hirshfeld surface analysis revealed that in both compounds H…H interactions have the major contribution to the molecular surface. From the energy framework analysis, it was found that the dispersion components have a major contribution in crystal. [ABSTRACT FROM AUTHOR]

Using a minimalist approach, an 11‐residue peptide (Peptide 1) tagged with rhodamine fluorophore was designed and synthesized for selective detection of cancer cells. Peptide 1 contains RGD and NGR motifs to bind, respectively, integrins and aminopeptidase CD13, which are over expressed in cancer cells. Surface tension measurements revealed that peptide 1 possess surface‐active property owing to the overall hydrophobicity and cationic nature of the peptide. Peptide 1 displays cancer cell‐selective binding at ≤5.0 µM concentrations, while peptide 2 (randomized sequence of 1) shows non‐selective binding to normal and cancer cells. Fluorescence microscopy and FACS analysis demonstrated the intracellular localization of peptide 1 in three different cancer cell lines, confirming the role of RGD and NGR motifs. Cytotoxicity assay exhibited the viability of normal and cancer cells up to 100 µM concentrations of peptide 1. Steady‐state fluorescence measurements disclosed the preferential interactions of the peptide 1 with anionic POPC/POPG bilayers rather than with zwitterionic POPC lipid bilayers. Circular dichroism studies showed minimal changes in the secondary structure of peptide 1 upon binding with the anionic lipid bilayers. Peptide 1 is largely unordered, non‐toxic, and useful for identification of cancer cells. Peptide 1 provides a template for designing drug‐loaded peptides for targeted delivery into cancer cells. [ABSTRACT FROM AUTHOR]

We report a triazole appended imidazopyridine based chemosensor (probe 1) for sequential detection of Cu2+ and CN− ions using fluorometry. Probe 1 is fluorescent in aqueous acetonitrile (H2O‐CH3CN, 1:1, v/v) when common metal ions are present, but the fluorescence is quenched when Cu2+ is present. The binding mechanism, quantitative determination and the mode of interaction of Cu2+ with probe 1 are explained using fluorescence spectroscopy, electrospray ionization mass spectrometry and Density Functional Theory (DFT) calculations. The observed detection limit for Cu2+ is found to be (18.17×10−6 M) and it is comparable with those reported for other Cu2+ chemosensors. Further, the 1–Cu2+ complex formation is found to be reversible, and this property has been successfully exploited for the quantitative determination of CN− ions in aqueous acetonitrile. Addition of CN– leads to a complete recovery of fluorescence from 1–Cu2+ complex, permitting the real time detection with the lower limit of detection of CN− being 33.57×10−6 M. The observed experimental results are supported by DFT calculations. A possible application of 1–Cu2+ in fluorescence imaging of Rhizoctonia solani mycelia cells, contaminated with CN− ions, is also represented. [ABSTRACT FROM AUTHOR]

A series of aryl/indolyl substituted 4, 5-dihydro-1H-pyrazole derivatives were synthesized via a domino method based on Michael addition mediated cyclization of appropriate chalcones. The chalcones were prepared by Witting reaction in which substituted aromatic aldehydes were treated with stable ylides under eco-friendly ultrasonic cavitation. The pyrazole scaffolds were obtained in excellent yields within a short span of time. [ABSTRACT FROM AUTHOR]

Highlights • Thiosemicarbazones derived phenyl-acetyl ketones as a novel class of protease inhibitors. • DB-TYR-TSC molecule derived from thiosemicarbazones act as a antiviral agent for dengue 2. • MTT assay and plaque reduction assays were employed for screening the viral inhibition. • High Potency and Excellent antiviral activity against dengue virus 2. • Augment the efforts to identify the lead compounds for antiviral therapy. Abstract Dengue fever is a severe, widespread disease with more than 2 million diagnosed infections per year. The Dengue virus protease represents a cardinal target for prudent drug design. Among the four serotypes Dengue 2 is known for the occurrence of its frequent epidemics. The new compound inhibited the Dengue-2 in the low-micromolar range in cells. At the moment, protease inhibitors are not actively tried against dengue virus as therapeutic option. We have identified thiosemicarbazones derived phenyl-acetyl ketones as candidate for a novel class of protease inhibitors. Here, we report the selective and non-competitive inhibition of the Dengue virus serotype 2 in vitro and in silico. Molecular docking suggests binding at a specific active site. In addition to the docking assays, few techniques were developed to interpret these molecules's antiviral profile in vitro. [ABSTRACT FROM AUTHOR]

An abstract of the article "Lewis Acid Catalyzed Unprecedented [3 + 2] Cycloaddition Yields 3,3'-Pyrrolidinyldispirooxindoles Containing Four Contiguous Chiral Stereocenters with Two Contiguous Quaternary Spirostereocenters" by K. Suman and colleagues is presented.

Synthesis and fluorescence turn-on behavior of a naphthalimide based probe is described. Selective interactions of trivalent cations Fe 3 + , Al 3 + or Cr 3 + with probe 1 inhibit the PET operating in the probe, and thereby, permit the detection of these trivalent cations present in aqueous samples and live cells. Failure of other trivalent cations (Eu 3 + , Gd 3 + and Nb 3 + ) to inhibit the PET process in 1 demonstrates the role of chelating ring size vis-à-vis ionic radius in the selective recognition of specific metal ions. [ABSTRACT FROM AUTHOR]

An efficient, solvent-free and 18-crown-6 catalyzed method for the synthesis of N-alkyl-4-(4-(5-(2-(alkyl-amino)thiazol-4-yl)pyridin-3-yl)phenyl)thiazol-2-amine, N-alkyl-4-(5-(2-alkyamino)thiazol-4-yl)pyridine-3-yl)thiazol-2-amine, and 4,4′-bis-{2-[amino]-4-thiazolyl}biphenyl bis-heterocyclic derivatives via microwave accelerated is presented. [ABSTRACT FROM AUTHOR]

A novel fluorescein-rhodamine dyad probe has been synthesized and its chemosensory applications are explored. Anion and cation specific responses of the probe permit ratiometric detection of Hg 2+ and fluoride ions, individually and collectively, with different fluorescence outputs. The presence of other commonly coexistent ions does not affect the Hg 2+ and fluoride ion detection ability of the probe. The probe is highly sensitive to Hg 2+ and fluoride ions and it can detect Hg 2+ and fluoride ions even at ppb level concentrations. The probe is non-toxic under the experimental conditions, cell permeable and useful for the imaging of intracellular Hg 2+ and fluoride ions. [ABSTRACT FROM AUTHOR]

Two new rhodamine–indole conjugates 1 and 2 were synthesized for studying their ability to probe specific metal ions at physiological pH in the presence of other competing metal ions. In non-aqueous medium, probe 1 predominantly binds Cu2+ ions with considerable interference from Fe3+ and Ni2+ ions. However, in aqueous medium, 1 exhibits a higher degree of selectivity for Cu2+ ions with little interference from Fe3+ ions, and no interference from Ni2+ ions. The probe 2, obtained by tethering a triazole moiety with probe 1, selectively binds Cu2+ ions in aqueous medium even in the presence of other metal ions including Fe3+ ions. The sensitivity of probe 2 to pH variation and interaction with various amino acids were also investigated. The excellent stability of 2 in physiological pH conditions, non-toxicity, non-interference of amino acids in the detection process, and the remarkable selectivity for Cu2+ ions in aqueous medium allowed the use of 2 in the imaging of live fibroblast cells treated with Cu2+. [ABSTRACT FROM AUTHOR]

Abstract: The number and nature of coordinating entities as well as the size of chelating cavity in rhodamine based chemosensors were tuned to enhance the selectivity and sensitivity for Fe3+ ions. An intense pink color development and enhancement in fluorescence emission intensity of chemosensor 5 upon complex formation at pH 7·4 enabled the detection of Fe3+ ions in the presence of other competitive metal ions like Li+, Na+, K+, Cs+, Mg2+, Ca2+, Sr2+, Cr3+, Mn2+, Fe2+, Cu2+, Co2+, Ni2+, Zn2+, Cd2+, Hg2+, and Pb2+. A plausible application of chemosensor 5 in the imaging of live fibroblast cells exposed to Fe3+ ions is also demonstrated. [Copyright &y& Elsevier]

Abstract: In the present paper, we report the micellization, aggregation behavior and thermodynamics of a cationic surfactant viz. cetyltrimethylammonium bromide (CTAB) in absence and presence of tyrosine-hydantoin (TH) drug. The solution behavior of the mixture of CTAB and TH drug has been determined using conductivity, surface tension, UV–visible and fluorescence spectroscopic methods. A strong interaction between the two amphiphiles is indicated from the above measurements. The critical micelle concentration (cmc) of CTAB is found to decrease with increase in the amount of TH in the mixture. The cmc values obtained by these methods are in good agreement with each other. The critical micelle concentration, aggregation number and standard free energy changes of aggregation of the surfactant (CTAB) in aqueous solution in absence and presence of TH are evaluated at different temperatures (294, 303 and 318K). The aggregation number is obtained by the steady-state fluorescence spectroscopic method. Thermodynamic parameters (the standard Gibbs energy change of micellization, ΔG ° m , the standard enthalpy change of micellization, ΔH ° m , the standard entropy change of micellization, ΔS ° m , the standard Gibbs (transfer) energy, , and the excess free energy change of micellization, ΔG ex) have been evaluated. The negative values of standard Gibbs energy change indicate spontaneous micellization and synergism. The interaction parameter, β m , activity coefficients (f 1, f 2) have been evaluated, and using these data we evaluated excess Gibbs energies, which indicate the spontaneity and the stability of the mixed micelles. [ABSTRACT FROM AUTHOR]

Electrospinning of Gelatin (G) and Poly-3-hydroxybutyric acid (P) incorporated with anionic drug (AgSD) loaded hydrotalcite (L) (L-AgSD) is carried out to fabricate a nanofibrous scaffold which would recreate the native extracellular matrix suitable for cutaneous regeneration. The L-AgSD complex was augmented into electrospun nanofibers of diameter 100–140 nm. The physiochemical (XRD, FTIR), morphological (SEM), mechanical (tensile strength) and biological (in vitro and in vivo) properties of the developed wound construct were studied. Antimicrobial studies reveal the potential activity against microbial infection. Studies on drug release kinetics demonstrate a controlled release of 86% in 72 h. In vitro biocompatibility studies using NIH 3T3 fibroblast cell line showed excellent cell adhesion and cell proliferation indicating the biocompatible nature of the scaffold. The matrix accelerated wound healing on Pseudomonas infected burn wound induced on rat models. The tailored matrix is promising as an impending nanohybrid construct for burn wound injuries with controlled drug release and antibacterial activity. Unlabelled Image • Anionic drug (AgSD) with hydrotalcite (L) (L-AgSD) as a durable nanofibrous construct • GP-(L-AgSD) n was fabricated as a nanofibrous hybrid construct with hydrotalcite • Drug release behavior and antibacterial action was excellent with GP-(L-AgSD) n matrix • Nanofibrous construct exhibited desirable physiochemical and biological properties • Healing efficiency of the burn wounds were promising with GP-(L-AgSD) n matrix [ABSTRACT FROM AUTHOR]

Synthesis and chelation induced fluorescence emission from two imidazo[1,2- a ]pyridine derivatives are described. The nonfluorescent molecule 1 containing N and O donor atoms, achieves coplanarity upon interactions with trivalent cations Al3+, Fe3+ and Cr3+, that favors fluorescence emission. Molecule 2 containing two N donor atoms attains coplanarity upon interaction with the only Zn2+ and becomes fluorescent. Both molecules 1 and 2 form a 1:1 complex with interacting metal ions. Other trivalent metal ions (including Bi3+ and In3+) and common divalent metal ions (including Hg2+ and Cd2+) fail to form any complex with 1 or 2 , and they do not interfere in the detection of Zn2+, Al3+, Fe3+ or Cr3+ ions. Noninterference of other metal ions renders 1 and 2 suitable for the detection of fungal cells contaminated with Zn2+, Al3+, Fe3+ or Cr3+ ions. Two structurally related bidentate nonplanar nonfluorescent molecules attain coplanarity through selective interactions with divalent Zn2+ and trivalent Al3+, Fe3+ and Cr3+ ions and emit fluorescence, permitting the detection of these metal ions. Unlabelled Image • Two imidazo[1,2- a ]pyridine based bidentate nonfluorescent molecules 1 and 2 form, respectively, a 1:1 complex with divalent Zn2+ and trivalent Fe3+, Al3+ and Cr3+ ions, adopt coplanar conformation, and show chelation induced fluorescence enhancement. [ABSTRACT FROM AUTHOR]

An abstract of the article "18-crown-6 catalyzed microwave-mediated synthesis of symmetric bis-heterocyclic compounds under solvent-free condition," by R. Rishekesan and colleagues is presented.