Amin Badshah

Drug–DNA interactions and their study by UV–Visible, fluorescence spectroscopies and cyclic voltametry

The present paper review the drug-DNA interactions, their types and applications of experimental techniques used to study interactions between DNA and small ligand molecules that are potentially of pharmaceutical interest. DNA has been known to be the cellular target for many cytotoxic anticancer agents for several decades. Understanding how drug molecules interact with DNA has become an active research area at the interface between chemistry, molecular biology and medicine. In this review article, we attempt to bring together topics that cover the breadth of this large area of research. The interaction of drugs with DNA is a significant feature in pharmacology and plays a vital role in the determination of the mechanisms of drug action and designing of more efficient and specifically targeted drugs with lesser side effects. Several instrumental techniques are used to study such interactions. In the present review, we will discuss UV-Visible spectroscopy, fluorescence spectroscopy and cyclic voltammetry. The applications of spectroscopic techniques are reviewed and we have discussed the type of information (qualitative or quantitative) that can be obtained from the use of each technique. Not only have novel techniques been applied to study drug-DNA interactions but such interactions may also be the basis for the development of new assays. The interaction between DNA and drugs can cause chemical and conformational modifications and, thus, variation of the electrochemical properties of nucleobases.

Synthesis, spectral characterization and bio-analysis of some organotin(IV) complexes.

Five novel organotin(IV) derivatives have been synthesized by refluxing trimethyl, triethyl, tributyl, and triphenyl and tribenzyltin chloride with Schiff base derived from salicylaldehyde and adenine. These compounds were characterized by spectroscopic (IR, (1)H, (13)C, (119)Sn-NMR, (119m)Sn Mössbauer) techniques and elemental analysis. Based on these results, trigonal bipyramidal geometry is suggested. The synthesized compounds were also treated with various microorganisms and found to be active.

Organotin esters of 3-(2-furanyl)-2-propenoic acid: their characterization and biological activity

Abstract Multinuclear NMR and Mossbauer spectroscopy have been carried out for d- and triorganotin carboxylates derived from 3-(-2-furanyl)-2-propenoic acid. Their spectroscopic characterization showd that triorganotin carboxylates are either 4-coordinate monomers or 5-coordinate polymers with bridging carboxylate groups. Although a polymeric structure is favoured for most compounds in the solid state, the solution studies indicated that they exist as monomeric 4-coordinate species in non-coordinating solvents. Diorganotin carboxylates of the general formula R2Sn(OOCCHCHC4H3O)2 and dimeric [(R2SnOOCCHCHC4H3O)2O]2 are penta-coordinate in noncoordinating solvents while in the solid phase intra- or intermolecular interactions are possible. Moreover, we report the fluxional behaviour of carboxylate anions in dimeric distannoxanes. The biological activity of these organotin carboxylates proved them to be powerful biocides.

Synthesis, characterization and anticancer studies of mixed ligand dithiocarbamate palladium(II) complexes

Six mixed ligand dithiocarbamate Pd(II) complexes (1-6) of general formula [(DT)Pd(PR(3))Cl], where DT = dimethyldithiocarbamate (1, 5), diethyldithiocarbamate (2, 3), dicyclohexyldithiocarbamate (4), bis(2-methoxyethyl)dithiocarbamate (6); PR(3) = benzyldiphenylphosphine (1), diphenyl-2-methoxyphenylphosphine (2), diphenyl-p-tolylphosphine (3), diphenyl-m-tolylphosphine (4), tricyclohexylphosphine (5), diphenyl-2-pyridylphosphine (6) have been synthesized and characterised using Elemental analysis, FT-IR, Raman and multinuclear magnetic resonance (NMR) spectroscopy. Compounds 1 and 2 were also characterized by single crystal X-ray diffraction technique (XRD). The XRD study reveals that the Pd(II) moiety has a pseudo square-planar geometry, in which two positions are occupied by the dithiocarbamate ligand in a bidentate fashion, while at the remaining two positions organophosphine and chloride are present. The anticancer activity of the synthesized metallodrugs was checked against DU145 human prostate carcinoma (HTB-81) cells, the IC(50) values indicate that the compounds are highly active against these cells. These Pd(II) complexes also show moderate antibacterial activity against gram positive and gram negative bacteria.

Synthesis, characterization, antimicrobial and antitumor screening of some diorganotin(IV) complexes of 2-[(9H-Purin-6-ylimino)]-phenol.

A new series of diorganotin(IV) complexes of the type R(2)SnL(2) (R=Me, Et, Bu, Ph, Bz and L=2-[(9H-Purin-6-ylimino)]-phenol) have been synthesized, characterized by elemental analyses and their solid state configuration has been determined by various spectroscopic (IR, (1)H, (13)C, (119)Sn NMR, (119m)Sn Mössbauer) techniques. The results obtained on the basis of these techniques are in full concurrence with the proposed 2:1 stoichiometry. The title complexes have been screened against various microorganisms, fungi and human cell line KB, the results obtained showed that the bis(2-[(9H-Purin-6-ylimino)]-phenolate) diphenyltin(IV) complex exhibited excellent activity against all types of bacteria and fungi used, while bis(2-[(9H-Purin-6-ylimino)]-phenolate) diethyltin(IV) complex was found to have promising antitumor activity.

Highly Porous Carbon Derived from MOF-5 as a Support of ORR Electrocatalysts for Fuel Cells

The development of highly competent electrocatalysts for the sluggish oxygen reduction reaction (ORR) at cathodes of proton-exchange membrane fuel cells (PEMFCs) is extremely important for their long-term operation and wide applications. Herein, we present highly efficient ORR electrocatalysts based on Pt/Ni bimetallic nanoparticles dispersed on highly porous carbon obtained via pyrolysis of a metal-organic framework MOF-5. In comparison to the commercial Pt/C (20%), the electrocatalyst Pt-Ni/PC 950 (15:15%) in this study exhibits a pronounced positive shift of 90 mV in Eonset. In addition, it also demonstrates excellent long-term stability and durability during the 500-cycle continue-oxygen-supply (COS) accelerating durability tests (ADTs). The significantly improved activity and stability of Pt-Ni/PC 950 (15:15%) can be attributed to the Pt electron interaction with Ni and carbon support as has been proved in X-ray and microscopic analysis.

Comparative Study of Structure - Activity Relationship of Di and Triorganotin (IV) Complexes of Monomethyl Glutarate

A series of di and triorganotin(IV) complexes of monomethyl glutarate have been synthesized and characterized through 1H 13C 119Sn NMR, FT-IR and 119Sn Mossbauer spectroscopy. On the basis of these techniques, it is proposed that the ligand molecule is bound to the tin atom through the carbonyl oxygen. The data reveal that diorganotin(IV) complexes exhibit hexa-coordination with octahedral geometry, while triorganotin(IV) complexes have penta-coordination with trigonal bipyramidal geometry. Biological evaluation against various microorganisms indicate that diorganotin(IV) complexes are less active than the triorganotin(IV) complexes.

Mössbauer, multinuclear magnetic resonance and mass spectrometric studies of organotin carboxylates of m-methyltrans-cinnamic acid

Abstract The synthesis and spectroscopic characterization (1H, 13C, 119Sn NMR, 119mSn Mossbauer and mass spectrometry) of a series of organotin carboxylates of m-methyl trans-cinnamic acid are described. Different literature methods have been successfully applied for the qualitative structural characterization of these compounds. Triorganotin carboxylates are essentially penta-coordinate in the solid state with R3SnO2 geometry, while tetracoordinate in non-coordinating solvents. Diorganotin carboxylates with a 1:2 molar ratio (R2SnO: 2HOCOR′) are hexa-coordinate as solids, while there is an equilibrium between hexa- and penta-coordinated states in solution. Moreover, compounds with a 1:1 molar ratio (R2SnO: HOCOR′), adopt a characteristic tetraorganodicarboxylato distannoxane structural mode. Interesting results have been observed for tricyclohexyltin derivatives and stannoxanes. 2D NMR has been employed for the assignments of protons of high-spin systems.

HYDROBORATION OF 1-ALKYNYL(CHLORO)SILANES-NEW SYNTHONS IN HETEROCYCLIC CHEMISTRY

Abstract The 1-alkynyl(chloro)dimethylsilanes R1CC(Cl)SiMe2 [1a (R1=Bu), 1b (R1=tBu)] react with tetraethyldiborane(6) to give the (Z)-1-chlorodimethylsilyl-1-diethylboryl-alkenes 2a,b. These alkenes react with N- or C-lithiated azoles (pyrazole, thiazole) by LiCl elimination and formation of the novel five-membered heterocycles 4a, 5b and 6b. In 5b and 6b, derived from thiazole and 4-methyl-thiazole, zwitterionic structures result which can be regarded as borane adducts of carbenes. All new compounds were characterised by 1H-, 11B-, 13C-, 14/15N- and 29Si-NMR spectroscopy

New supramolecular ferrocenyl amides: synthesis, characterization, and preliminary DNA-binding studies

Three ferrocenyl amides have been synthesized and characterized by analytical techniques. Based on single-crystal X-ray analysis, a supramolecular structure was attributed to 1 owing to the presence of intermolecular non-covalent interactions. UV-Visible spectroscopy, viscometry, and dynamic laser light scattering was used to assess the mode of interaction and binding of these complexes with DNA, which varied in the sequence 1 > 2 > 3. The binding is presumably due to the ability of these complexes to form secondary non-covalent interactions with DNA bases. Complex-DNA adduct formation depends on the nature of R of the amide.