Synthesis, characterization and cytotoxicity of some palladium(II), platinum(II), rhodium(I) and iridium(I) complexes of ferrocenylpyridine and related ligands. Crystal and molecular structure of trans-dichlorobis(3-ferrocenylpyridine)palladium(II)

The preparation of a series of ferrocenyl nitrogen donor ligands including ferrocenylpyridines, ferrocenylphenylpyridines and 1,1^′-di(2-pyridyl)ferrocene is described. Coordination studies of the substituted pyridines (L) were carried out with platinum, palladium, rhodium and iridium. This resulted in the preparation of the following types of complexes: [MCl(CO)₂(L)] and [M(cod)(L)₂]ClO₄ where M=Rh or Ir, cod=1,5-cyclooctadiene; [M^′Cl₂(L)₂] where M^′=Pt or Pd. The X-ray crystal structure of trans-dichlorobis(3-ferrocenylpyridine)palladium was obtained. The complexes were screened for activity against two human cancer cell lines. At least two of the complexes displayed growth inhibition similar to that of the widely used chemotherapeutic agent, cisplatin.     

Detection and characterization of recombinant DNA expressing <Emphasis Type="Italic">vip3A</Emphasis>-type insecticidal gene in GMOs—standard single,multiplex and construct-specific PCR assays

Vegetative insecticidal protein (Vip), a unique class of insecticidal protein, is now part of transgenic plants for conferring resistance against lepidopteron pests. In order to address the imminent regulatory need for detection and labeling of vip3A carrying genetically modified (GM) products, we have developed a standard single PCR and a multiplex PCR assay. As far as we are aware, this is the first report on PCR-based detection of a vip3A-type gene (vip-s) in transgenic cotton and tobacco. Our assay involves amplification of a 284-bp region of the vip-s gene. This assay can possibly detect as many as 20 natural wild-type isolates bearing a vip3A-like gene and two synthetic genes of vip3A in transgenic plants. The limit of detection as established by our assay for GM trait (vip-s) is 0.1%. Spiking with nontarget DNA originating from diverse plant sources had no inhibitory effect on vip-s detection. Since autoclaving of vip-s bearing GM leaf samples showed no deterioration/interference in detection efficacy, the assay seems to be suitable for processed food products as well. The vip-s amplicon identity was reconfirmed by restriction endonuclease assay. The primer set for vip-s was equally effective in a multiplex PCR assay format (duplex, triplex and quadruplex), used in conjunction with the primer sets for the npt-II selectable marker gene, Cauliflower mosaic virus 35S promoter and nopaline synthetase terminator, enabling concurrent detection of the transgene, regulatory sequences and marker gene. Further, the entire transgene construct was amplified using the forward primer of the promoter and the reverse primer of the terminator. The resultant amplicon served as a template for nested PCR to confirm the construct integrity. The method is suitable for screening any vip3A-carrying GM plant and food. The availability of a reliable PCR assay method prior to commercial release of vip3A-based transgenic crops and food would facilitate rapid and efficient regulatory compliance. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. An application for an Indian patent (1891/DEL2006/17.08.07) comprising a substantive part of this study has been filed. ITRC communication no. 2516.     

Mechanistic studies on pyridoxal phosphate synthase: the reaction pathway leading to a chromophoric intermediate

Two routes for the de novo biosynthesis of pyridoxal-5'-phosphate (PLP) have been discovered and reconstituted in vitro. The most common pathway that organisms use is dependent upon the activity of just two enzymes, known as Pdx1 (YaaD) and Pdx2 (YaaE) in bacteria. Pdx2 has been shown to have glutaminase activity and most likely channels ammonia to the active site of the PLP synthase subunit, Pdx1, where ribose-5-phosphate (R5P), glyceraldehyde-3-phosphate (G3P), and ammonia are condensed in a complex series of reactions. In this report we investigated the early steps in the mechanism of PLP formation. Under pre-steady-state conditions, a chromophoric intermediate (I320) is observed that accumulates upon addition of only two of the substrates, R5P and glutamine. The intermediate is covalently bound to the protein. We synthesized C5 monodeuterio (pro-R, pro-S) and dideuterio R5P and showed that there is a primary kinetic isotope effect on the formation of this intermediate using the pro-R but not the pro-S labeled isomer. Furthermore, it was shown that the phosphate unit of R5P is eliminated rather than hydrolyzed in route to intermediate formation and also that there is an observed C5-deuterium kinetic isotope effect on this elimination step. Interestingly, it was observed that the formation of the intermediate could be triggered in the absence of Pdx2 by the addition of high concentrations of NH4Cl to a preincubated solution of Pdx1 and R5P. The formation of I320 was also monitored using high-resolution electrospray ionization Fourier transform mass spectrometry and revealed a species of mass 34,304 Da (Pdx1 + 95 Da). These results allow us to narrow the mechanistic possibilities for the complex series of reactions involved in PLP formation.     

Development and Validation of LC-UV for Simultaneous Estimation of Rosiglitazone and Glimepride in Human Plasma

A simple, sensitive and specific liquid chromatographic method with UV detection (228 nm) was developed for the simultaneous estimation of rosiglitazone and glimepride in human plasma. Rosiglitazone and glimepride were extracted from plasma using liquid–liquid extraction. Separation was achieved with an RP C₁₈ Column using a mixture of phosphate buffer (50 mM) with octane sulfonic acid (10 mM), methanol and acetonitrile as a mobile phase (55:10:35, v/v). pH was adjusted to 7.0. Amlodipine was used as an internal standard (IS). LOD of the method was found to be 20 ng mL^?1 for both drugs. Results were linear over the studied range 40.994–2007.556 ng mL^?1 for rosiglitazone (r ² ≥ 0.99) and 41.066–2094.84 ng mL^?1 for glimepride( r ² ≥ 0.99). The method was found to be simple, selective, precise and reproducible for the estimation of both drugs from spiked human plasma.     

Model studies of azide binding to functional analogues of CcO

N3- binding to a functional model of CcO is investigated in its Fe3+, Fe3+Cu+, and Fe3+Cu2+ forms. A combination of EPR and FTIR indicates that N3- binds in a bridging mode in the bimetallic sites and signature N3- bands are identified for several forms of N3- binding to the site. The presence of the distal metal increases the binding affinity of N3-. This bridging enables antiferromagnetic interaction between the two metal centers in the Fe3+Cu2+ state, which results in an EPR-silent ground state.     

Mechanistic studies on a Cu-catalyzed aerobic oxidative coupling reaction with N-phenyl tetrahydroisoquinoline: structure of intermediates and the role of methanol as a solvent

The mechanism of an aerobic copper-catalyzed oxidative coupling reaction with N-phenyl tetrahydroisoquinoline was investigated. The oxidized species formed from the reaction of the amine with the copper catalyst were analyzed by NMR-spectroscopy. An iminium dichlorocuprate was found to be the reactive intermediate and could be structurally characterized by X-ray crystallography. The effect of methanol to effectively stabilize the iminium ion was investigated and shown to be beneficial in an oxidative allylation reaction.     

one-pot synthesis of pyrrolo-[3,4-d]isoxazoline-4,6-diones via nitrile oxides

1,3-Dipolar cycloaddition of nitrile oxides generated in situ in the presence of variously substituted N-arylmaleimides and N-benzylmaleimide provides new pyrrolo[3,4-d]izoxazoline-4,6-diones in good yields. The whole procedure could be performed in a practical and efficient one-pot operation. All the cycloadducts were isolated in excellent yields and identified by spectral studies. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 444–448, March, 2009.     

Sulfuric acid immobilized on silica: an efficient reusable catalyst for selective hydrolysis of the terminal O-isopropylidene group of sugar derivatives

Sulfuric acid immobilized on silica proved to be an efficient catalyst for selective hydrolysis of the terminal O-isopropylidene group of sugar derivatives. The method is very simple and economic for large-scale synthesis in which the catalyst is recovered and reused for several runs. Reactions with di-O-isopropylidene derivatives of d-glucose, d-mannose, d-fructose and l-sorbose led to the formation of the corresponding mono-O-isopropylidene derivatives in good to excellent yields.