Synthesis and biological evaluation of novel 2-aralkyl-5-substituted-6-(4 `-fluorophenyl)-imidazo2,1-b]1,3,4]thiadiazole derivatives as potent anticancer agents

Levamisole, the imidazo2,1-b]thiazole derivative has been reported as a potential antitumor agent. In the present study, we synthesized, characterized and evaluated biological activity of its novel analogues with substitution in the aralkyl group and on imidazothiadiazole molecules with same chemical backbone but different side chains namely 2-aralkyl-6-(4'-fluorophenyl)-imidazo2,1-b]1,3,4]thiadiazoles (SCR1), 2-aralkyl-5-bromo-6-(4'-fluorophenyl)-imidazo2,1-b]1,3,4]-thiadiaz oles (SCR2), 2-aralkyl-5-formyl-6-(4'-fluorophenyl)-imidazo2,1-b]1,3,4]-thiadia zoles (SCR3) and 2-aralkyl-5-thiocyanato-6-(4'-fluorophenyl)-imidazo2,1-b]1,3,4]-th iadiazoles (SCR4) on leukemia cells. The cytotoxic studies showed that 3a, 4a, and 4c exhibited strong cytotoxicity while others had moderate cytotoxicity. Among these we chose 4a (IC50, 8 mu M) for understanding its mechanism of cytotoxicity. FACS analysis in conjunction with mitochondrial membrane potential and DNA fragmentation studies indicated that 4a induced apoptosis without cell cycle arrest suggesting that it could be used as a potential chemotherapeutic agent. (C) 2011 Elsevier Masson SAS. All rights reserved.

Stereospecific and regioselective catalytic epoxidation of alkenes by a novel ruthenium(II) complex under aerobic conditions

Epoxidation of alkenes by molecular oxygen is effected in high yields by catalysis of RuCl2(biox)(2) using isobutyraldehyde as the co-reductant: the reaction is stereospecific and regioselective.

Studies of moisture induced crosslinking in a novel vinyl ether maleic anhydride copolymer

A novel vinyl ether, 2,2-dimethyl-4-vinyioxymethyl-1,3-dioxol (DMVMD), that has a dimethyl ketal protected vicinal diol functionality was synthesizied from readily available starting materials, such as glycerol, acetone and acetylene. Copolymerisation of DMVMD with maleic anhydride (MAH) in various molar ratios was carried out using a free radical initiator. The composition of the copolymer was established by conductometric titration, and was found to be 1:1 irrespective of the monomer feed composition thus establishing its alternating nature. The copolymer formed clear free standing films upon solvent casting which became insoluble upon prolonged exposure to ambeint atmosphere. The insolubility is ascribed to moisture induced crosslinking. A plausible mechanism for the crosslinking involves the hydrolysis of some of the anhydride groups, followed by acid catalysed deketalization, and then by the reaction of the alcoholic groups, thus generated, with the residual anhydride to give ester crosslinks. This hypothesis was confirmed both by model reactions and insitu FT-IR studies.

Synthesis and vesicle formation from novel pseudoglyceryl dimeric lipids. Evidence of formation of widely different membrane organizations with exceptional thermotropic properties

Eight new bis-cationic dimeric lipids 2a-h have been synthesized; TEM of their aqueous dispersions confirmed the vesicle formation and from the thermal, spectroscopic, DLS and XRD studies it has been revealed that they form three different kinds of membranous aggregate depending on the m-value.

Interesting reaction of 2,2 '-binaphthol with 1,2-dibromoethane: Synthesis of a novel spirodienone

2,2'-Binaphthol 1 reacts with 1,2 dibromoethane in the presence of potassium carbonate to give rise to a novel spirodienone system 3 and its structure has been confirmed by X-ray analysis.

Synthesis, spectral characterization and in vitro microbiological evaluation of novel glyoxal, biacetyl and benzil bis-hydrazone macrocyclic Schiff bases and their Co(II), Ni(II) and Cu(II) complexes

A series of binuclear Co(II), Ni(II) and Cu(II) complexes were synthesized by the template condensation of glyoxal, biacetyl or benzil bis-hydrazide, 2,6-diformyl-4-methylphenol and Co(11), Ni(II) or Cu(II) chloride in a 2:2:2 M ratio in ethanol. These 22-membered macrocyclic complexes were characterized by elemental analyses, magnetic, molar conductance, spectral, thermal and fluorescence studies. Elemental analyses suggest the complexes have a 2:1 stoichiometry of the type (M2LX2]center dot nH(2)O and Ni(2)LX(2)2H(2)O]center dot nH(2)O (where M = Co(II) and Cu(II); L = H2L1, H2L2 and H2L3; X = Cl; n = 2). From the spectroscopic and magnetic studies, it has been concluded that the Co(11) and Cu(11) complexes display a five coordinated square pyramidal geometry and the Ni(II) complexes have a six coordinated octahedral geometry. The Schiff bases and their metal complexes have also been screened for their antibacterial and antifungal activities by the MIC method. (C) 2011 Elsevier Ltd. All rights reserved.

Growth inhibitory, apoptotic and anti-inflammatory activities displayed by a novel modified triterpenoid, cyano enone of methyl boswellates

Triterpenoids are pentacyclic secondary metabolites present in many terrestrial plants. Natural triterpenoids have been reported to exhibit anti-inflammatory and anti-carcinogenic activities. Here, we show that modifications of ring A of boswellic acid (2 cyano, 3 enone) resulted in a highly active growth inhibitory, anti-inflammatory, pro-differentiative and anti-tumour triterpenoid compound called cyano enone of methyl boswellates (CEMB). This compound showed cytotoxic activity on a number of cancer cell lines with IC50 ranging from 0.2 to 0.6 mu M. CEMB inhibits DNA synthesis and induces apoptosis in A549 cell line at 0.25 mu M and 1 mu M concentrations, respectively. CEMB induces adipogenic differentiation in 3T3-L1 cells at a concentration of 0.1 mu M. Finally, administration of CEMB intra-tumourally significantly inhibited the growth of C6 glioma tumour xenograft in immuno-compromised mice. Collectively, these results suggest that CEMB is a very potent anti-tumour compound.

Novel materials, materials design and synthetic strategies: recent advances and new directions

There have been major advances in solid state and materials chemistry in the last two decades and the subject is growing rapidly. In this account, a few of the important aspects of materials chemistry of interest to the author are presented. Accordingly, transition metal oxides, which constitute the most fascinating class of inorganic materials, receive greater attention, Metal-insulator transitions in oxides, high temperature superconductivity in cuprates and colossal magnetoresistance in manganates are discussed at some length and the outstanding problems indicated, We then discuss certain other important classes of materials which include molecular materials, biomolecular materials and porous solids. Recent developments in synthetic strategies for inorganic materials are reviewed. Some results on metal nanoparticles and nanotubes are briefly presented. The overview, which is essentially intended to provide a flavour of the subject and show how it works, lists references to many crucial reviews in the recent literature.

Synthesis and characterization of novel charge transfer complexes formed by N,N%-bis(ferrocenylmethylidene)-p-phenylenediamine and N-(ferrocenylmethylidene)aniline

N,N'-Bis(ferrocenylmethylidene)-p-phenylenediamine 1 and N-(ferrocenylmethylidene) aniline 2 are readily synthesized by Schiff base condensation of appropriate units. Iodine (I-2), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), tetrachloro-1,4-benzoquinone (CA), tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) form charge transfer complexes with 1 and 2. IR spectroscopy suggests an increase in the amount of charge transferred from the ferrocenyl ring to the oxidant in the order, I-2 < CA < TCNQ < TCNE approximate to DDQ. EPR spectra of the oxidized binuclear complexes are indicative of localized species containing iron- and carbon-centered radicals. The Mossbauer spectrum of the iodine oxidized complex of 1 reveals the presence of both Fe(III) and Fe(II) centers. Variable temperature magnetic and Mossbauer studies show that the ratio of Fe(III)/Fe(II) centers varies as a function of temperature. The larger Fe(II)/Fe(III) ratio at lower temperatures is best explained by a retro charge transfer from the iodide to the iron(III) metal center. There is negligible solvent effect on the formation of the iodine oxidized charge transfer complex of 1. (C) 1999 Elsevier Science S.A. All rights reserved.

Synthesis and structure of a novel terminal imido complex of titanium

The reaction of eta(5)-Cp*TiCl3 and (LiNHBu)-Bu-t in hexanes yields a novel [eta(5)-Cp*Ti(=(NBu)-Bu-t)((NHBu)-Bu-t)(2)]Li . (NH2Bu)-Bu-t complex with a terminal tert-butylimido moiety. The synthesis and X-ray structural characterization are described. (C) 1999 Elsevier Science S.A. All rights reserved.

Synthetic studies towards novel terpenic natural products kelsoene and poduran: Construction of the complete 4-5-5-fused tricarbocyclic core

A common synthetic approach to the recently reported sesquiterpene kelsoene 1 and the tetraterpene poduran 5, bearing a novel tricyclo[6.2.0.0(2,6)]decane framework, from commercially available 1,5-COD and leading to the first construction of the carbocyclic core present in these natural products is delineated.