S. Mohana Roopan

Fungus-mediated biosynthesis and characterization of TiO2 nanoparticles and their activity against pathogenic bacteria

In the present study, the biosynthesis of TiO(2) nanoparticles (TiO(2) NPs) was achieved by a novel, biodegradable and convenient procedure using Aspergillus flavus as a reducing and capping agent. Research on new, simple, rapid, eco-friendly and cheaper methods has been initiated. TiO(2) NPs were characterized by FTIR, XRD, AFM, SEM and TEM studies. The X-ray diffraction showed the presence of increased amount of TiO(2) NPs which can state by the presence of peaks at rutile peaks at 100, 002, 100 and anatase forms at 101 respectively. SEM observations revealed that synthesized TiO(2) NPs were spherical, oval in shape; individual nanoparticles as well as a few aggregate having the size of 62-74 nm. AFM shows crystallization temperature was seen on the roughness of the surface of TiO(2). The Minimum inhibitory concentration value for the synthesized TiO(2) NPs was found to be 40 μg ml(-1) for Escherichia coli, which was corresponding to the value of well diffusion test. This is the first report on antimicrobial activity of fungus-mediated synthesized TiO(2) NPs, which was proved to be a good novel antibacterial material.

New diketone based vanadium complexes as insulin mimetics

Since 1985, when Heyliger et al. first reported the in vivo insulin mimetic activity of oral vanadate, extensive studies exploring vanadium chemistry, including the synthesis of novel complexes and their biological effects both in vitro and in vivo have been pursued. Such complexes have emerged as possible potential agents for diabetes therapy. Among the several existing compounds, diketone based vanadium complexes have been chosen for the current study. Two new complexes namely bisdimethylmalonatooxovanadium(IV) and bisdiethylmalonatooxovanadium(IV) have been synthesized and characterized by UV-visible, FTIR and mass spectral studies. The antidiabetic activity of the complexes was proved by animal study. The results show that the above complexes have comparable antidiabetic potential with respect to the standard drug as well as with bisacetylacetonatooxovanadium(IV) which has been studied earlier by Reul et al.

SYNTHESIS OF O-SUBSTITUTED BENZOPHENONES BY GRIGNARD REACTION OF 3-SUBSTITUTED ISOCOUMARINS

ABSTRACT A series of o-substituted benzophenones was prepared by efficient method involving the 3-substituted isocoumarins and phenylmagnesium bromide. The reaction was completed in presence of anhydrous ether under dry ice-solvent bath in few hours with modest to good yields.Key words: Isocoumarins, diketones, aryl, phenyl magnesium bromide, ether, dry ice.e-mail: nawaz_f@yahoo.co.in. INTRODUCTION Synthetic and naturally occurring isocoumarins possess important biological properties. They are useful intermediates in the synthesis of a variety of carbocyclic and heterocyclic compounds 1-6 .In continuous of our interest in carbon-carbon bond formation reaction 7-12 ,the present paper presents an efficient method to synthesize o-substituted benzophenones (2) from 3-substitued isocoumarins (1) and phenyl magnesium bromide in presence of anhydrous ether under dry ice-solvent bath. Benzophenone and its derivatives are important intermediates in dyes, pharmaceutical and other chemical industries

SYNTHESIS OF 3 SUBSTITUTED ISOQUINOLIN-1-YL-2-(CYCLOALK-2-ENYLIDENE) HYDRAZINES AND THEIR ANTIMICROBIAL PROPERTIES

New hydrazine derivatives were synthesized via reaction between 1, 3 cyclic diketones and hydrazinoisoquinoline derivatives. The reaction proceeded smoothly in ethanol under reflux temperature and furnished products in excellent yields (76–87%). The products have been purified and fully characterized by spectroscopy techniques. The compounds 8a-c showed good bacterial inhibition against Bacillus cerus and 8d-f showed good antifungal activity against Candida albicans.

Agricultural waste as a source for the production of silica nanoparticles

The major interest of the paper deals with the extraction of silica from four natural sources such as rice husk, bamboo leaves, sugarcane bagasse and groundnut shell. These waste materials in large quantities can create a serious environmental problem. Hence, there is a need to adopt proper strategy to reduce the waste. In the present investigation, all the waste materials are subjected to moisture removal in a hot plate and sintered at 900°C for 7 h. The sintered powder was treated with 1 M NaOH to form sodium silicate and then with 6M H2SO4 to precipitate silica. The prepared silica powders were characterized by FT-IR, XRD and SEM-EDAX analysis. The silica recovered from different sources was found to vary between 52% and 78%. Magnesium substituted silica was formed from the groundnut waste and further treatment is required to precipitate silica.

2-Chloro-3-hydroxy-methyl-6-methoxy-quinoline.

All the non-H atoms of the title compound, C11H10ClNO2, are roughly coplanar (r.m.s. deviation = 0.058 Å). In the crystal, adjacent molecules are linked by an O—H⋯N hydrogen bond, generating chains running along the a axis.

SYNTHESIS AND FREE RADICAL SCAVENGING PROPERTY OF SOME QUINOLINE DERIVATIVES

In the present work synthesis of 2-chloroquinoline-3-carbaldehydes (1a-g), 2-chloro-3-(1, 3-dioxolan-2-yl)quinolines (2a-g) and antioxidant activity using the DPPH assays is reported. The results showed that the compounds 1b, 1c, 2b, 2e, 2f possessed 84.65 to 85.75 % radical scavenging activity where as compound 1g showing 92.96% radical scavenging activity. due to high contents of certain phenolic compounds in plant-derived foods. Recently, phytochemicals and their effects on human health have been intensively studied. In particular, a search for antioxidants 3 , hypoglycemic agents 4 , and anticancer agents 5 in vegetables, fruits, tea, spices and medicinal herbs has attracted great attention. Naturally occurring plant phenolics include several groups of compounds that have health promoting properties. Phenolics may act as antioxidants, thereby reducing the risk of atherosclerosis and coronary heart disease, which can be caused by oxidation of low-density lipoproteins. They also may protect against some forms of cancer 6 . Quinoline moiety is mostly present in a medicinal plant whose tubers possesses cardiovascular, anti-inflammatory and antiparasitic effects and has been used for the treatment of hepatitis, rheumatism and diarrhea 7 . A solution of 2-chloroquinoline-3-carbaldehydes 1 (10 mmol) in benzene (50 mL) containing ethylene glycol (1.78 g, 1.6 mL, 28.5 mmol) and a crystal of toluene-p-sulfonic acid was heated under reflux for 5 hours using a Dean-Stark water separator until no more water collected in the side arm. The cooled solution was treated with saturated aqueous sodium carbonate (50 mL), Benzene layer separated, dried and evaporated giving 2 which was recrystallised from petroleum ether gave a yellowish white solid. The product was characterized by NMR, GCMS techniques. Similar proce- dures were followed for the synthesis of other quinoline derivatives 2a-g and Table 1. The spectral data of the compounds 1(a-g) & 2(a-g) is given below. 2-Chloroquinoline-3-carbaldehyde

2-Chloro-3-hydroxy-methyl-7,8-dimethyl-quinoline.

All non-H atoms of the title compound, C12H12ClNO, are co-planar (r.m.s. deviation = 0.055 Å). The hydroxy H atom is disordered over two positions of equal occupancy. In the crystal, molecules are linked by O—H⋯O hydrogen bonds, generating zigzag chains running along the b axis.

Isocoumarin Thioanalogues as Potential Antibacterial Agents

A series of 3-substituted-1H-isochromene-1-thiones (3) were prepared by the reaction of 3-substituted isocoumarins (2) with Lawessons reagent in the presence of toluene under a nitrogen atmosphere. The antimicrobial activities of the newly synthesized products were measured using Gram-negative (Escherichia coli, Salmonella typhi, and Proteus mirabilis) and Gram-positive bacteria (Staphylococcus aureus and Bacillus cereus). Synthesized thioanalogue of isocoumarins showed good antibacterial activity against Proteus mirabilis.

Regioselective O-alkylation: synthesis of 1-{2-[(2-chloroquinolin-3-yl)methoxy]-6-chloro-4-phenylquinolin-3-yl}ethanones

An efficient and regioselective O-alkylation of amides with a variety of electrophiles in the presence of silver nanoparticles is reported as part of our recent research on building blocks for synthesis of natural products. The nano-silver catalyst initiates O-alkylation of the amides by heteroalkyl halides. Reaction of equimolar 3-acetyl-6-chloro-4-phenylquinolin-2(1H)-one and 2-chloro-3-(chloromethyl)quinolines in the presence of silver nanoparticles in DMSO solution under reflux condition leads to the formation of 1-{1-[2-chloroquinolin-3-yl)methoxy]-6-chloro-4-phenylquinolin-3-yl}ethanones.