Two new flavonoids from Andrographis rothii

Two new flavonoids, 5, 7, 2', 5'-tetramethoxyflavanone (1) and 5-hydroxy-7, 2'-dimethoxyflavone (2), together with two known flavones, skullcapflavone I (3) and echioidin (4) were isolated from the whole plant of Andrographis rothii. The structures of the new compounds were established by extensive one- and two-dimensional (1D- and 2D-) NMR spectral studies.     

Synthesis of some novel annelated 1,2,3‐selena/thiadiazoles and 2h‐diazaphospholes

A number of annelated heterocyclic indene derivatives having 1,2,3‐selena/thiadiazole and 2H‐1,2,3‐diazaphosphole rings have been synthesized by exploiting the α‐ketomethylene functionality in some novel 1‐methyl‐piperidin‐4‐ones and 1‐oxo‐tetrahydrothiopyran‐4‐ones and were characterized by their physical and spectral data.     

A new route to the synthesis of isoxazoline derivatives from dihydropyran via cycloaddition reaction in ionic liquid

A new approach to the synthesis and 1,3-dipolar cycloadditions of nitrones has been described from 2,3-dihydro-4H-pyran and various hydroxylamines, with electron-deficient alkynes for the synthesis of isoxazoline derivatives. Significant rate acceleration and improved yields of exclusively exo isoxazolines in 1-butyl-3-methylimidazolium based ionic liquids have been observed. Novel isoxazolines may be used as a precursor for the synthesis of variety of peptides.     

Enantioselective Hydrolysis of 2, 2-Disubstituted Oxiranes Mediated by Microsomal Epoxide Hydrolase

2-Aryl-2-methyloxiranes are enantioselectively hydrolyzed with microsomal epoxide hydrolase from pig liver to provide 1, 2-diols containing a tertiary benzylic alcohol stereogenic centre upto 34% enantio-meric purities.     

DNA-directed assembly of polyanilines: modified cytosine nucleotides transfer sequence programmability to a conjoined polymer

A series of polyaniline (PANI) oligomers was constructed from monomer units covalently linked to duplex DNA through N-(2-aminoethyl) groups bonded through cytosines. DNA oligomers containing the aniline monomers were treated with horseradish peroxidase (HRP) and H2O2 under conditions known to cause polymerization of aniline. No change in the absorption spectrum of the DNA was observed for samples containing fewer than four contiguous aniline groups. However, for oligomers containing four, five, or six aniline units, treatment with HRP and H2O2 led to the appearance of absorption features characteristic of the conducting "proton doped" emeraldine oxidation state of PANI. Molecular modeling shows that the DNA is distorted in the region of the PANI, but flanking regions of the DNA maintain their B-form structure. These findings provide a method to exploit the self-recognition, self-assembly, and sequence programmability of DNA for the formation of conducting polymers.     

Development and validation of a rapid ultra high performance liquid chromatography with tandem mass spectrometry method for the simultaneous determination of darunavir,ritonavir, and tenofovir in human plasma: Application to human pharmacokinetics

A sensitive ultra high performance liquid chromatography with tandem mass spectrometry method was developed for the simultaneous determination of darunavir, ritonavir and tenofovir in human plasma. Sample preparation involved a simple liquid–liquid extraction using 200 μL of human plasma extracted with methyl tert‐butyl ether for three analytes and internal standard. The separation was accomplished on an Acquity UPLC BEH C₁₈ (50 mm x 2.1 mm, 1.7 μm) analytical column using gradient elution of acetonitrile/methanol (80:20, v/v) and 5.0 mM ammonium acetate containing 0.01% formic acid at a flow rate of 0.4 mL/min. The linearity of the method ranged between 20.0 and 12 000 ng/mL for darunavir, 2.0 and 2280 ng/mL for ritonavir, and 14.0 and 1600 ng/mL for tenofovir using 200 μL of plasma. The method was completely validated for its selectivity, sensitivity, linearity, precision and accuracy, recovery, matrix effect, stability, and dilution integrity. The extraction recoveries were consistent and ranged between 79.91 and 90.04% for all three analytes and internal standard. The method exhibited good intra‐day and inter‐day precision between 1.78 and 6.27%. Finally the method was successfully applied for human pharmacokinetic study in eight healthy male volunteers after the oral administration of 600 mg darunavir along with 100 mg ritonavir and 100 mg tenofovir as boosters.     

Arrays of horizontally-oriented mini-reservoirs generate steady microfluidic flows for continuous perfusion cell culture and gradient generation

This paper describes the use of arrays of horizontally-oriented reservoirs to deliver liquids through microchannels at a constant flow rate over extended periods of time (hours to days). The horizontal orientation maintains a constant hydraulic pressure drop across microfluidic channels even as the volumes of liquids within the reservoirs change over time. For a given channel-reservoir system, the magnitude of the flow velocity depends linearly on the height difference between reservoirs. The simple structure and operation mechanism make this pumping system versatile. A one-inlet-one-outlet system was used to continuously deliver media for perfusion cell culture, and an array of inlet reservoirs coupled to an outlet reservoir via microchannels was used to drive flows of multiple laminar streams. The parallel pumping scheme conveniently generated various smooth and step concentration gradients, and allowed evaluation of the effect of colchicine on myoblasts. Since the reservoir arrays are configured to be compatible with commercialized multichannel pipettors designed for 96 well plate handling, this simple pumping scheme is envisioned to be broadly useful for medium to high throughput microfluidic perfusion cell culture assays, cell migration assays, multiple laminar flow drug tests, and any other applications needing multiple microfluidic streams.     

An antiferromagnetically coupled dimeric Ni(II) complex anion and its counter cationic monomeric Ni(II) complex, and some other mononuclear transition metal compounds using some neutral ligands

Synthesis and single crystal X-ray diffraction studies of four transition metal complexes [Mn(L₁)](ClO₄)₂ (1), [Cu(L₁)](ClO₄)₂ (2), [Ni₂(L₂)(NCS)₆][Ni(L₁)] (3) and [Mn(bzpy)(NCS)₂] (4) with neutral ligands [L₁ = N-(1-pyridin-2-yl-phenylidene)-N′-[2-({2-[(1-pyridin-2-yl phenylidene)amino]ethyl}amino)ethyl]ethane-1,2diamine, L₂ = N-(1-pyridin-2-yl-phenylidene)-N′-[2-({2-[(1-pyridin-2-ylphenylidene)amino]ethyl}piperazine-1yl)ethyl]amine, bzpy = 2-benzoylpyridine] are reported. The trinuclear nickel(II) complex 3 is made of a dinuclear anion and a mononuclear cation. Variable-temperature magnetic susceptibility and variable-field magnetisation studies performed on 3 suggest weak antiferromagnetic coupling (J = −0.7 cm⁻¹) between the two metals of the dinuclear entity, but no magnetic interaction between the anionic and cationic counterparts.     

A general synthetic approach for the synthesis of β-hydroxy-δ-lactones: asymmetric total synthesis of prelactones and epi-prelactones V and E

A general synthetic approach for the synthesis of prelactones and epi-prelactones V and E has been reported using an Evans’ aldol reaction as the key step.     

Exploration of an arabinogalactan isolated from Odina wodier Roxb.: Physicochemical,compositional characterisations and functional attributes

Exudate gum polysaccharides have a diverse range of functionalities in food, cosmetics, textiles, biomedical, pharmaceutical and other industries for centuries. The potentiality of gum odina as tablet binder, coacervates (chitosan‐gum odina complex) for colon‐targeted drug delivery system and also as prebiotic with immunomodulating properties was reported earlier. Since no detail study of the physicochemical, functional properties of the gum has been reported, the present investigation deals with physicochemical, compositional and functional characterisations of purified gum odina (PGO) for adopting in food and pharmaceutical industry. PGO, an arabinogalactan, was obtained by ethanol precipitation from exudates (gum odina) of tropical deciduous plant Odina wodier Roxb. Colour profiling of PGO including L* (87.74 ± 0.42), a* (1.73 ± 0.65) and b* (7.79 ± 0.58) was determined. Physicochemical parameters revealed good flow ability and compressibility desired for an excipient. Concentration‐dependent surface tension was measured by du Noüy ring method. Rheological study showed pseudoplastic behaviour of PGO dispersion. Sugar analysis by gas liquid chromatography indicated presence of arabinogalactan in PGO. Size exclusion chromatography of PGO revealed two high‐molecular‐weight components PGO‐I (95%, Arabinose:Galactose :: 1:1.6) and PGO‐II (5%, Arabinose:Galactose :: 1:4). Further characterisations of PGO by means of CHNS, FTIR, differential scanning calorimetry, X‐ray diffraction, transmission electron microscopy, scanning electron microscopy and energy‐dispersive X‐ray diffraction, conductivity, pH, zeta potential analysis and antioxidant activity indicated typical polysaccharide characteristics. Collectively, this work established the fundamental properties of PGO and the results presented here will facilitate the applications of PGO as sustainable food additive, pharmaceutical excipient for commercial adoption.