Colorimetric and Fluorimetric DNA Detection with a Hydroxystyryl–Quinolizinium Photoacid and Its Application for Cell Imaging

The combination of styryl dye properties with the acidity and strong photoacidity of the 2,2′-[(1′′-hydroxy-4′′-methyl-(E)-2′′,6′′-phenylene)]-bisquinolizinium enables the detection of DNA by distinct absorption and emission color changes and the fluorimetric detection of DNA in cells with epifluorescence and confocal fluorescence microscopy.     

Isolation,structural elucidation and in vitro antioxidant activity of compounds from chloroform extract of Cedrus deodara (Roxb.) Loud.

This study was designed to isolate, characterise and explore in vitro antioxidant potential of compounds from the chloroform extract of Cedrus deodara wood belonging to Pinacae family. We have investigated the in vitro free radical scavenging activity of isolated compounds by measuring total antioxidant capacity (TAC) and reducing power ability. From the chloroform extract five sesquiterpenes namely atlantone, himaphenolone, atlantolone, deodardione and atlantone-2,3-diol were identified. Himaphenolone and deodardione from the chloroform extract of this plant have been isolated for the first time. A marked dose-dependent reducing power and strong TAC were found in favour of himaphenolone and atlantone-2,3-diol, respectively. Moreover, deodardione and atlantolone also exhibit good antioxidant potentials. However, atlantone has showed least antioxidant activity. In conclusion, the chloroform extract of C. deodara exhibited significant antioxidant potential mainly due to the presence of sesquiterpenes which may be responsible for various pharmacological activities of this plant.     

Standing waves in a non-linear 1D lattice: Floquet multipliers, Krein signatures, and stability

We construct a class of exact commensurate and incommensurate standing wave (SW) solutions in a piecewise smooth analogue of the discrete non-linear Schrödinger (DNLS) model and present their linear stability analysis. In the case of the commensurate SW solutions the analysis reduces to the eigenvalue problem of a transfer matrix depending parametrically on the eigenfrequency. The spectrum of eigenfrequencies and the corresponding eigenmodes can thereby be determined exactly. The spatial periodicity of a commensurate SW implies that the eigenmodes are of the Bloch form, characterised by an even number of Floquet multipliers. The spectrum is made up of bands that, in general, include a number of transition points corresponding to changes in the disposition of the Floquet multipliers. The latter characterise the different band segments. An alternative characterisation of the segments is in terms of the Krein signatures associated with the eigenfrequencies. When one or more parameters characterising the SW solution is made to vary, one occasionally encounters collisions between the band-edges or the intra-band transition points and, depending on the the Krein signatures of the colliding bands or segments, the spectrum may stretch out in the complex plane, leading to the onset of instability. We elucidate the correlation between the disposition of Floquet multipliers and the Krein signatures, presenting two specific examples where the SW possesses a definite window of stability, as distinct from the SW’s obtained close to the anti-continuous and linear limits of the DNLS model.     

A macrocyclic piperazine linked extremely Zn selective fluorescent chemosensor with bio-imaging and for H2PO4 sensing

A new macrocyclic fluorescent chemosensor piperazine coupled diimine phenol (PCDP) which forms extremely selective Zn(II) complex and thus builds up the platform for H₂PO₄⁻ (DHP) sensing in mixed aqueous medium, has been designed and synthesized. The binding of PCDP with Zn²⁺ and its displacement by DHP have been supported by DFT studies. The blue fluorescence in the PCDP–Zn complex is useful for bio-imaging. The fluorescence enhancement of PCDP on association with Zn²⁺ ion is quenched sharply in the presence of intracellular DHP.     

Photoinduced electron transfer within a novel synthesized short-chain dyad

The investigations were made by using electrochemical, steady state and time resolved spectroscopic (time correlated single photon counting and laser flash photolysis) techniques on a novel synthesized dyad, 1-(4-chloro-phenyl)-3-(4-methoxy-naphthalen-1-yl)-propenone (MNCA) where the donor 1-methoxy-naphthalene (MNT) is connected with the acceptor p-chloroacetophenone (PCA) by an unsaturated olefinic bond. This dyad possesses mainly extended (E-type) conformation both in the ground and excited state. The unchanged conformational geometry of this dyad even after photoexcitation makes it different from the previously studied benzothiophene-p-chloroacetophenone dyads, though both the donors present are isosteric molecules. In the cases of the latter dyads though E-type isomeric structure dominates in the ground state, considerable amount of Z-type (folded) species are produced in the excited state. It is hinted that the proximity effect of methoxy functionality in donor moiety, may be the reason for the formation of mostly E-isomeric species in the case of the present dyad MNCA system. The observed unchanged values of charge recombination and ion-pair lifetime, estimated from the analysis of transient absorption spectra of the dyad in presence of βCD and without it, confirm the proposition about the maintenance of the extended conformation even upon photoexcitation. From the transient absorption measurements it appears that due to increase of delay times between the exciting and probe pulses, higher triplet T_n of the donor being generated gets involved in PET reactions with the surrounding medium ACN. From the present findings, MNCA in aqueous medium seems to be better candidate to build light energy conversion devices than the previously studied benzothiophene dyads where artificial devices like βCD were used to make elongated geometry. This geometry would help to prevent charge recombination processes within the redox components due to minimal overlapping between them.     

Curvature inequalities for operators in the Cowen-Douglas class and localization of the Wallach set

For any bounded domain Ω in ?^m, let B₁(Ω) denote the Cowen-Douglas class of commuting m-tuples of bounded linear operators. For an m-tuple T in the Cowen-Douglas class B₁(Ω), let N_T (w) denote the restriction of T to the subspace \(\cap^m_{i,j=1}{\rm{ker}}(T_i-w_iI)(T_j-w_jI)\). This commuting m-tuple N_T (w) of m + 1 dimensional operators induces a homomorphism \({\rho _{{N_T}\left( w \right)}}\) of the polynomial ring P[z₁, · · ·, z_m], namely, \({\rho _{{N_T}\left( w \right)}}\) (p) = p(N_T (w)), p ∈ P[z₁, · · ·, z_m]. We study the contractivity and complete contractivity of the homomorphism \({\rho _{{N_T}\left( w \right)}}\). Starting from the homomorphism \({\rho _{{N_T}\left( w \right)}}\), we construct a natural class of homomorphisms \(\rho_{N^{(\lambda)}(w)}\), λ > 0, and relate the properties of \(\rho_{N^{(\lambda)}(w)}\) to those of \({\rho _{{N_T}\left( w \right)}}\). Explicit examples arising from the multiplication operators on the Bergman space of Ω are investigated in detail. Finally, it is shown that contractive properties of \({\rho _{{N_T}\left( w \right)}}\) are equivalent to an inequality for the curvature of the Cowen-Douglas bundle E_T. However, we construct examples to show that the contractivity of the homomorphism ρ_T does not follow, even if \({\rho _{{N_T}\left( w \right)}}\) is contractive for all w in Ω.     

Requirement of aggregation propensity of Alzheimer amyloid peptides for neuronal cell surface binding

Background  

Aggregation of the amyloid peptides, Aβ40 and Aβ42, is known to be involved in the pathology of Alzheimer's disease (AD). Here we investigate the relationship between peptide aggregation and cell surface binding of three forms of Aβ (Aβ40, Aβ42, and an Aβ mutant).     

Simple and efficient synthesis of 2,7-difunctionalized-1,8-naphthyridines

The syntheses in good yields of some new difunctionalized 1,8-naphthyridines 4, 6, 8 and 9 and a novel triethylene glycol ether-linked dinaphthyridine, 10a, along with the mononaphthyridine-linked ether alcohol 10b are described. An improved and milder method for the synthesis of 2,7-diamino-1,8-naphthyridine (14) is also reported.     

Spectroscopic and thermodynamic study of charge transfer complexes of cloxacillin sodium in aqueous ethanol medium

Cloxacillin sodium has been shown to form charge transfer (CT) complexes of 1:1 stoichiometry with a number of electron acceptors in 50% (v/v) aqueous ethanol medium. From the trends in the CT absorption bands, the vertical ionization potential of the drug molecule (cloxacillin sodium) has been estimated to be 7.89 eV. The enthalpies and entropies of formation of two such complexes have been determined by estimating the formation constants spectrophotometrically at five different temperatures. The oscillator strengths and transition dipole moments of these complexes have been determined. It has further been noted that the reduction of o-chloranil by aqueous ethanol is completely inhibited by cloxacillin sodium, a phenomenon that makes the present study of formation equilibrium possible.