Spectroscopic identification of binding modes of anthracene probes and DNA sequence recognition

The binding properties of two anthracene derivatives with calf thymus DNA (CT DNA), poly(dA-dT), and poly(dG) x poly(dC) are reported. One contained bulky, cyclic cationic substituents at the 9 and 10 positions, and the other carried acylic, branched, cationic substituents. Binding of the probes to the DNA was examined by calorimetry, spectroscopy and helix melting studies. The cyclic derivative indicated exothermic binding, strong hypochromism, bathochromism, positive induced circular dichroism (CD, 300-400 nm), significant unwinding of the helix, large increases in the helix melting temperature, strong but negative linear dichroism (LD, 300-400 nm) and considerable stabilization of the helix. In contrast, the acyclic analog indicated thermoneutral binding, smaller hypochromism, no bathochromism, very weak induced CD, and no change in the helix melting temperature with any of the DNA polymers. A sharp distinction between the binding properties of the two probes is indicated, and both have intrinsic binding constants of approximately 10(6) M(-1) for the three polymers. However, when the ionic strength of the medium was lowered (10 mM NaCl), the absorption as well as CD spectral changes associated with the binding of the acyclic derivative corresponded with those of the cyclic derivative. The acyclic derivative showed large preference (10-fold) for poly(dG) x poly(dC) over poly(dA-dT), whereas the cyclic analog showed no preference. The characteristic spectroscopic signatures of the two distinct binding modes of these probes will be helpful in deciphering the interaction of other anthracene derivatives with DNA.     

Simultaneous Determination of Etodolac and Acetaminophen in Tablet Dosage Form by RP-LC

A simple, specific, precise and accurate reverse phase liquid chromatographic (RP-LC) method has been developed for the simultaneous determination of etodolac and acetaminophen in tablet dosage form. The chromatographic separation was achieved on a BDS Hypersil C18, 100 mm × 4.6 mm, 5 μm column at a detector wavelength of 274 nm using an isocratic mobile phase consisting of a mixture of 0.05% aqueous orthophosphoric acid and acetonitrile in the ratio of 50:50 (v/v) at a flow rate of 1.0 mL min^?1. The retention times for etodolac and acetaminophen were found to be 1.32 and 4.24 min, respectively. The method was validated for the parameters like specificity, linearity, precision, accuracy and robustness. The method was found to be specific and stability indicating as no interfering peaks of impurities, degradent and excipients were observed. The square of correlation coefficients (R ²) for etodolac and acetaminophen were 0.9996 and 0.9998 while percentage recoveries were 101.32 and 100.94%, respectively. Intra- and inter-day relative standard deviations for both the components were <2.0%. The proposed RP-LC method can be applied for the routine analysis of commercially available formulations of these drugs either as such or in combination.     

Detection of Vibrational Spectroscopic Biomarkers of the Effect of Gold Nanoparticles on Wheat Seedlings Using Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy

The aim of this study is to evaluate the biochemical changes in the leaves of wheat seedlings exposed to gold nanoparticles (AuNPs) nondestructively and rapidly using attenuated total reflectance Fourier transform infrared spectroscopy and laser-induced fluorescence. The 18?nm size gold nanoparticles are synthesized by citrate reduction. For analyzing the effect of gold nanoparticles on wheat seedlings, the treatment of gold nanoparticles was applied to the seedlings through roots and following the spectroscopic measurement of biochemical signatures. The laser-induced fluorescence measurement has been performed to access the effect of gold nanoparticles on the chlorophyll concentration of wheat seedlings. The decrease in the fluorescence intensity and the fluorescence intensity ratio on the treatment of gold nanoparticles indicates increase in the concentration of chlorophyll in the leaves of wheat seedlings. The attenuated total reflectance Fourier transform infrarred spectroscopy in combination with principal component analysis has been used to visualize the biochemical changes in the cellulose, hemicellulose, pectin, lignin, amino acids, proteins, and lipid of the leaves of wheat seedlings by recording infrared spectra in the region from 4000 to 400?cm^?1. Principal component analysis applied to the preprocessed infrared data clearly distinguishes the spectral variability between control and gold nanoparticle treated seedlings. The study shows that exposure of gold nanoparticles increases the concentrations of cellulose, hemicelluloses, pectin, and lignin in the leaves of wheat seedlings. The increase in these chemicals indicates the modulation of cell walls of the wheat seedlings by the gold nanoparticle treatment. The exposure to gold nanoparticles also enhances the expression of lipid and proteins in the leaves of wheat seedlings.     

Steady state and time resolved laser-induced fluorescence of garlic plants treated with titanium dioxide nanoparticles

The study involves investigation of the effect of the interaction of titanium dioxide nanoparticles with garlic plant by spectroscopy techniques. For this, garlic plants have been grown in the laboratory under controlled conditions of light flux, temperature, humidity, and nutrient media. The growth and biomass parameters in terms of shoot length, fresh, and dry mass are found to increase upon the treatment of titanium dioxide nanoparticles while a reduction is observed in the root length of the garlic plants. The steady state laser-induced fluorescence, time resolved laser-induced fluorescence, and ultraviolet visible spectra of the control and titanium dioxide nanoparticles-treated plants have been acquired. The curve fitting data reveal that titanium dioxide nanoparticles decrease the intensity and fluorescence intensity ratio of red and far red chlorophyll fluorescence bands indicating increase in the photosynthetic activity and chlorophyll content. The evaluation of life time of the excited chlorophyll molecule shows that life time is effected by the treatment of the titanium dioxide nanoparticles. The results pertaining to ultraviolet visible measurement indicate increase in the concentration of chlorophyll a, chlorophyll b, total chlorophyll, carotenoid, and quercetin in the leaves of garlic plants treated with titanium dioxide nanoparticles.     

Diversity in Chemical Structures and Biological Properties of Plant Alkaloids

Phytochemicals belonging to the group of alkaloids are signature specialized metabolites endowed with countless biological activities. Plants are armored with these naturally produced nitrogenous compounds to combat numerous challenging environmental stress conditions. Traditional and modern healthcare systems have harnessed the potential of these organic compounds for the treatment of many ailments. Various chemical entities (functional groups) attached to the central moiety are responsible for their diverse range of biological properties. The development of the characterization of these plant metabolites and the enzymes involved in their biosynthesis is of an utmost priority to deliver enhanced advantages in terms of biological properties and productivity. Further, the incorporation of whole/partial metabolic pathways in the heterologous system and/or the overexpression of biosynthetic steps in homologous systems have both become alternative and lucrative methods over chemical synthesis in recent times. Moreover, in-depth research on alkaloid biosynthetic pathways has revealed numerous chemical modifications that occur during alkaloidal conversions. These chemical reactions involve glycosylation, acylation, reduction, oxidation, and methylation steps, and they are usually responsible for conferring the biological activities possessed by alkaloids. In this review, we aim to discuss the alkaloidal group of plant specialized metabolites and their brief classification covering major categories. We also emphasize the diversity in the basic structures of plant alkaloids arising through enzymatically catalyzed structural modifications in certain plant species, as well as their emerging diverse biological activities. The role of alkaloids in plant defense and their mechanisms of action are also briefly discussed. Moreover, the commercial utilization of plant alkaloids in the marketplace displaying various applications has been enumerated.     

Quasilinear parabolic problem with <Emphasis Type="Italic">p</Emphasis>(<Emphasis Type="Italic">x</Emphasis>)-laplacian: existence,uniqueness of weak solutions and stabilization

We discuss the existence and uniqueness of the weak solution of the following quasilinear parabolic equation

$$\left\{\begin{array}{ll}u_t-\Delta _{p(x)}u = f(x,u)&\quad \text{in }\quad Q_T \stackrel{{\rm{def}}}{=} (0,T)\times\Omega,\\u = 0 & \quad\text{on}\quad \Sigma_T\stackrel{{\rm{def}}}{=} (0,T)\times\partial\Omega,\\u(0,x)=u_0(x)& \quad \text{in}\quad \Omega \end{array}\right.\quad\quad (P_{T})$$

involving the p(x)-laplacian operator. Next, we discuss the global behaviour of solutions and in particular some stabilization properties.

     

Synthesis of an oligodeoxyribonucleotide adduct of mitomycin C by the postoligomerization method via a triamino mitosene

The cancer chemotherapeutic agent mitomycin C (MC) alkylates and cross-links DNA monofunctionally and bifunctionally in vivo and in vitro, forming six major MC-deoxyguanosine adducts of known structures. The synthesis of one of the monoadducts (8) by the postoligomerization method was accomplished both on the nucleoside and oligonucleotide levels, the latter resulting in the site-specific placement of 8 in a 12-mer oligodeoxyribonucleotide 26. This is the first application of this method to the synthesis of a DNA adduct of a complex natural product. Preparation of the requisite selectively protected triaminomitosenes 14 and 24 commenced with removal of the 10-carbamoyl group from MC, followed by reductive conversion to 10-decarbamoyl-2,7-diaminomitosene 10. This substance was transformed to 14 or 24 in several steps. Both were successfully coupled to the 2-fluoro-O(6)-(2-trimethylsilylethyl)deoxyinosine residue of the 12-mer oligonucleotide. The N(2)-phenylacetyl protecting group of 14 after its coupling to the 12-mer oligonucleotide could not be removed by penicillinamidase as expected. Nevertheless, the Teoc protecting group of 24 after coupling to the 12-mer oligonucleotide was removed by treatment with ZnBr2 to give the adducted oligonucleotide 26. However, phenylacetyl group removal was successful on the nucleoside-level synthesis of adduct 8. Proof of the structure of the synthetic nucleoside adduct included HPLC coelution and identical spectral properties with a natural sample, and (1)H NMR. Structure proof of the adducted oligonucleotide 26 was provided by enzymatic digestion to nucleosides and authentic adduct 8, as well as MS and MS/MS analysis.     

Proteomic analysis of conditioned media from glucose responsive and glucose non-responsive phenotypes reveals a panel of secreted proteins associated with beta cell dysfunction

Media conditioned by dysfunctioning pancreatic beta cells offer an excellent source of potential protein markers associated with this phenotype. Proteins identified from cell culture model systems are often found to be of importance clinically. Previous work by us and others have shown that low-passage MIN-6 cells (MIN-6(L)) respond to changes in glucose concentrations, producing an approximately 5.5-fold glucose-stimulated insulin secretion (GSIS) in response to 26.7 mmol/L, compared with 3.3 mmol/L, glucose. After continuous culture or high-passage (MIN-(H)), this GSIS was no longer present and thus represents an excellent model system for investigating beta cell dysfunction. Employing 2-D difference gel electrophoresis and mass spectrometry a panel of protein markers were identified in conditioned media (CM) from MIN-6(L) and MIN-6(H) beta cells. These proteins, including secretogranin II, secretogranin III and transthyretin, are associated with secretory granule biogenesis and were found to have substantially increased levels in the CM from the non-responsive high-passage MIN-6 beta cells. A panel of protein markers found to have increased abundance levels in CM from MIN-6(H) compared with MIN-6(L) beta cells may have the potential to be used clinically for assessing beta cell function and to monitor the effects of specific therapeutics.     

Synthesis,characterization, and catalytic oxidation of styrene,cyclohexene, allylbenzene,and cis-cyclooctene by recyclable polymer-grafted Schiff base complexes of vanadium(IV)

Schiff base-functionalized chloromethylated polystyrenes, PS-[Ae-Eol] (I), PS-[Hy-Eda] (II) and PS-[HyP-Eda] (III), were synthesized by reacting 2-(2-aminoethoxy)ethanol (Ae-Eol), N-(2-hydroxyethyl)ethylenediamine (Hy-Eda), and N-(2-hydroxpropyl)ethylenediamine (HyP-Eda) with oxidized chloromethylated polystyrene. Oxidized chloromethylated polystyrene (PS-CHO) was prepared by oxidation of chloromethylated polystyrene (PS) with sodium bicarbonate in DMSO. By reacting DMSO solution of [VO(acac)₂] with polymer-anchored Schiff base ligands I, II, and III, vanadium(IV) complexes PS-[V^IVO(Ae-Eol)] (1), PS-[V^IVO(Hy-Eda)] (2), and PS-[V^IVO(HyP-Eda)] (3) were prepared. Structure and bonding of I, II, and III as well as corresponding vanadium complexes 1, 2, and 3 were confirmed by FT-IR, UV–vis spectroscopy, SEM, EDX, AAS, TGA, EPR, etc. Polymer-anchored vanadium(IV) complexes 1, 2, and 3 show, efficient catalysis toward oxidation of styrene, cyclohexene, allylbenzene, and cis-cyclooctene in the presence of hydrogen peroxide. Optimized reaction conditions for the oxidation of these alkenes was achieved by changing various reaction parameters (like amount of catalyst, amount of oxidizing agent, volume of solvent, etc.). Polymer-grafted 1, 2, and 3 can be reused multiple times without depletion of their activity.