Asimafoetidnol: a new sesquiterpenoid coumarin from the gum resin of Ferula assa-foetida

Chemical investigation of the gum resin of Ferula assa-foetida L. resulted in the isolation of a new sesquiterpenoid coumarin, 7-(((E)-5-((1S,3S,6S)-3,6-dihydroxy-2,2,6-trimethylcyclohexyl)-3-methylpent-2-en-1-yl)oxy)-2H-chromen-2-one (asimafoetidnol), together with several other known compounds. The structure of asimafoetidnol was established on the basis of spectroscopic analyses. Geometry optimization of the compound has been carried out using a DFT/B3LYP/3-21G* method.     

Simultaneous parallel and antiparallel self-assembly in a triazole/amide macrocycle conformationally homologous to D-,L-α-amino acid based cyclic peptides: NMR and molecular modeling study

A 1,4-linked triazole/amide based peptidomimetic macrocycle, synthesized from a triazole amide oligomer of cis-furanoid sugar triazole amino acids, possesses a conformation resembling the D-,L-α-amino acid based cyclic peptides despite having uniform backbone chirality. It undergoes a unique mode of self-assembly through an antiparallel backbone to backbone intermolecular H-bonding involving amide NH and triazole N2/N3 as well as parallel stacking via amide NH and carbonyl oxygen H-bonding, leading to the formation of a tubular nanostructure.     

Biogenic synthesis of Ag, Au and bimetallic Au/Ag alloy nanoparticles using aqueous extract of mahogany (Swietenia mahogani JACQ.) leaves

In this paper, we have demonstrated for the first time, the superb efficiency of aqueous extract of dried leaves of mahogany (Swietenia mahogani JACQ.) in the rapid synthesis of stable monometallic Au and Ag nanoparticles and also Au/Ag bimetallic alloy nanoparticles having spectacular morphologies. Our method was clean, nontoxic and environment friendly. When exposed to aqueous mahogany leaf extract, competitive reduction of Au(III) and Ag(I) ions present simultaneously in same solution leads to the production of bimetallic Au/Ag alloy nanoparticles. UV-visible spectroscopy was used to monitor the kinetics of nanoparticles formation. UV-visible spectroscopic data and TEM images revealed the formation of bimetallic Au/Ag alloy nanoparticles. Mahogany leaf extract contains various polyhydroxy limonoids which are responsible for the reduction of Au(III) and Ag(I) ions leading to the formation and stabilization of Au and Ag nanopaticles.     

Biomimetic preparation of polymer-supported free radical scavenging, cytocompatible and antimicrobial "green" silver nanoparticles using aqueous extract of Citrus sinensis peel

In the pursuit of making the nanoscale-research greener, the utilization of the reductive potency of a common byproduct of food processing industry i.e. orange peel is reported here to prepare biopolymer-templated "green" silver nanoparticles. Aqueous extract of orange peel at basic pH was exploited to prepare starch supported nanoparticles under ambient conditions. The compositional abundance of pectins, flavonoids, ascorbic acid, sugars, carotenoids and myriad other flavones may be envisaged for the effective reductive potential of orange peel to generate silver nanoparticles. The nanoparticles were distributed within a narrow size spectrum of (3-12 nm) with characteristic Bragg's reflection planes of fcc structure, and surface plasmon resonance peak at 404 nm. Anti-lipid peroxidation assay using goat liver homogenate and DPPH scavenging test established the anti-oxidant potency of the silver nanoparticles. Their synergy with rifampicin against Bacillus subtilis MTCC 736 and cytocompatibility with the human leukemic monocytic cell line, THP-1 were also investigated. Thus, the present work deals with the preparation of starch assisted anti-microbial, cytocompatible and free radical scavenging "green" silver nanoparticles.     

Preconcentration of 198Au in a green alga, Rhizoclonium</p> </p>

Summary The bioaccumulation of ¹⁹⁸Au radionuclide, by Rhizoclonium riparium a member of Chlorophyceae has been studied. It has been observed that accumulation of gold on Rhizoclonium is almost pH independent and slightly higher at basic pH. Accumulation of gold was studied with ¹⁹⁸Au radiotracer, 0.1, 1 and 5 ppm concentrations of gold. It has been concluded from the biochemical analysis that the gold accumulation is due to adsorption in the cellulose and not in protein, fat and carbohydrate. Accumulated gold was recovered when washed with conc. HNO₃.</p> </p>     

Immunoassay for the detection of lead ions in environmental water samples

A rapid, simple, and reliable competitive immunoassay was developed for measurement of lead ions Pb(II) in environmental samples. Avian antibodies were produced against Pb(II). Since lead ions are too small to elicit an immune response, the metal was coupled to protein carrier Bovine serum albumin (BSA) using a bifunctional chelator 1-(4-isothiocyanobenzyl) ethylenediamine N,N,N′,N′-tetra acetic acid (ITCBE). Poultry birds (layers) were immunised with this Pb(II)–ITCBE–BSA immunoconjugate and the avian antibodies (IgY) isolated from egg yolk recognised Pb(II)-ITCBE complexes as capture reagent and a Pb(II)–ITCBE conjugate of Alkaline phosphatase as an enzyme label. Antibody reaction was optimised for different concentrations of antigen and antibody dilutions. Cross reactivity with other metals were below 1% in competitive ELISA. The IC₅₀ value of this avian antibody was 0.19?µg?mL^?1. The detection range and the detection limit were 0.02–1000?µg?mL^?1and 0.2?µg?mL^?1, respectively.