Lok Ranjan Bhatt

Carboxyl–polyethylene glycol–phosphoric acid: a ligand for highly stabilized iron oxide nanoparticles

A new and simple synthetic strategy allows the direct introduction of phosphoric acid anchoring group and carboxyl functional group into polyethylene glycol (PEG), leading to strong binding to iron oxide nanoparticle surfaces through bidentate or tridentate Fe–O–P coordination bonds, and providing functionality for further conjugation of targeting ligands. The carboxyl–PEG–phosphoric-acid-stabilized nanoparticles exhibited extremely high stability in various harsh aqueous environments. The in vivo magnetic resonance imaging (MRI) results showed that the nanoparticles exhibited a long blood circulation time and accumulated in lymph nodes, which indicates that the stabilized Fe3O4 nanoparticles are highly stable in the blood stream and are of exceptionally small hydrodynamic diameter. A promising, rapid, easy synthetic procedure, and a successful in vivo MRI application demonstrate the potential of these functionalized nanoparticles as ideal candidates for biomedical applications.

Anti-human rhinovirus activity of gallic acid possessing antioxidant capacity

Human rhinoviruses (HRVs) are a major cause of the common cold and until now there is no registered clinically effective antiviral chemotherapeutic agent for treatment of diseases caused by HRVs. Our previous report showed that gallic acid from Woodfordia fruticosa flowers possessed antioxidant activity. Many studies reported that antioxidants possess antiviral activities against various viruses. Therefore, we examined antiviral activity of gallic acid against HRVs and mode of its actions by observing the effect of gallic acid on HRV‐induced cytopathic effect (CPE) and the infectivity of HRV particles, and then carried out a time‐addition study. As a result, gallic acid actively inhibited HRV2 and ‐3 replications with antiviral activity more than 55% without cytotoxicity in human epitheloid carcinoma cervix (HeLa) cells at a concentration of 100 μg/mL. Also, ribavirin showed lower anti‐HRV3 activity than gallic acid and similar anti‐HRV3 activity to it. The addition of gallic acid to HRV‐infected HeLa cells directly reduced the formation of a visible CPE. Furthermore, gallic acid did directly interact or activate with HRV particles. Collectively, we concluded that the inhibition of HRV production by gallic acid is mainly due to a general action as an antioxidant and the mode of action derived from the inhibition of virus absorption. Copyright

Preparation of chitin butyrate by using phosphoryl mixed anhydride system.

Acylation of chitin with butyric acid was performed in the presence of trifluoroacetic anhydride/phosphoric acid mediated system. The products were characterized by (1)H NMR and FT-IR spectroscopy and their solubility was tested in different organic solvents. Inclusion of butyric acid moieties into the parent molecule was confirmed from the (1)H NMR and FT-IR spectra. FT-IR analysis revealed that the degree of acid substitution (DS) of the products was in a range of 1.9-2.38, which increased with increasing the amounts of butyric acid added to the reaction system. Degree of N-deacetylation (DD) of the products, as determined by (1)H NMR was between 54.2% and 65.6%. The products with DS >2.0 were soluble in dimethyl sulfoxide, N,N-dimethylformamide, tetrahydrofuran, methanol, acetone, chloroform, and acetic acid.

A chalcone glycoside from the fruits of Sorbus commixta Hedl.

Sorbus commixta Hedl. (Rosaceae) has been traditionally used in oriental countries for the treatment of asthma and other bronchial disorders. In this study, a chalcone glycoside was isolated from the ethyl acetate extract of the fruits of this plant. The compound was identified as neosakuranin based on the spectroscopic analysis and comparion with literature data. This is the first report of isolation of neosakuranin from Sorbus commixta.

Synthesis of chitin cycloalkyl ester derivatives and their physical properties

A series of acylated chitin derivatives was prepared by reacting chitin in a solution of trifluoroacetic anhydride and each of the cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl carboxylic acids. The degree of O-acyl substitution was in a range of 1.1-1.4 depending upon the nature of the cyclic acid added, as determined by FT-IR analysis. The solubility of the products in the organic solvents of DMF and THF increased with an increase in the cyclic chain length of the carboxylic acid. Thermal gravimetric analysis indicated that the products were stable up to 220 degrees C for chitin cyclopropanoate and cyclobutanoate, and 250 degrees C for chitin cyclopentanoate and cyclohexanoate. The surface morphology of the products by scanning electron microscopic analysis revealed porous and globular surface for chitin cyclobutanoate, cyclopentanoate, and cyclohexanoate, contrast to the dense and smooth organization for the cyclopropanoate.

Preparation and Characterization of Chitin Benzoic Acid Esters

Chitin benzoic acid esters were prepared using a phosphoryl mixed anhydride method. The products were characterized by 1H-NMR and FT-IR spectroscopy. FT-IR analysis revealed that the degree of O-acyl substitution of the products was in a range of 1.17–1.83. Morphological surface changes in the parent molecule due to the introduction of benzoic acid moieties were observed by scanning electron microscopy. The surface of the products was porous, in contrast to the sheet-shape of the parent molecules. The solubility of the products, which improved with increased degree of acid substitution, was tested in various organic solvents.

Inhibitory effect of sakuranetin on (1,3)-β-glucan synthase

SUMMARY An examination of the kinetic properties of UDP-glucose, (1,3)-β-glucans (callose) synthase, frommung bean seedlings ( Sorbus commixta cortex ) shows that these enzymes have a complex relationship withUDP-glucose and various effectors. Fluorescence assay showed that deoxynojirimycin increasedthe inhibitory effect of (1,3)-β-glucan synthase in a concentration-dependent manner. Theinhibitory effect of sakuranetin (34.34%) was higher than that of deoxynojirimycin (80.63%). Diskdiffusion method revealed that sakuranetin inhibited the growth of Candida albicans to a 1.5 mminhibition zone. These results suggest that sakuranetin, isolated from Sorbus commixta cortexextract, can be used as stable antifungal material. Key words: (1,3)-β-glucan synthase; Sorbus commixta cortex; Fluorescence assay; Inhibitory effect;Sakuranetin; Candida albicans INTRODUCTION (1,3)-β-Glucans play important roles in themorphogensis of fungi and higher plants. Inhigher plants, this polymer has a common name,callose. Callose is only found as a wall polymer inspecialized cell types such as pollen mother cellsand pollen tubes. In addition, callose is depositedrapidly in plants in environmental conditions, andin response to pathogen attack (Stone et al., 1992).Essentially all higher plants contain a UDP-glucose[(1→3)-β-glucan (callose) synthase]. This enzyme islargely found on the plasma membrane, and inmost cases is latent, only becoming activated byperturbed conditions which lead to some loss ofmembrane permeability (Delmer et al., 1977; Delmer,1983). In 1979, Ray (1979) named this enzyme glucansynthetase II and assayed it at high concentrationsof UDP-Glc in the absence of divalent cations.However, others have reported that its activity canbe enhanced by Mg

Antiradical activity of Azadirachta indica extracts and fractions

In present study, total phenolic content of crude extract and antiradical activity of crude extract and different solvent fractions of Azadirachta indica were evaluated. Crude extract and most of the polar fractions showed higher radical scavenging activity. Among the crude extract and nine different fractions, the aqueous/methanol (3:1) fraction showed the highest activity.

Antioxidant capacity of crude extract and fractions from Woodfordia fruticosa flower

Woodfordia fruticosa Kurz. (Lythraceae), commonly known as Dhayero, is used in the treatment of various ailments in Nepal. In this study, the antioxidant capacity of crude extract and different polarity fractions of Woodfordia fruticosa flowers were assayed for their scavenging abilities against 1,1-diphenyl-2-picrylhydrazyl (DPPH) and nitric oxide radicals, competitive -carotene bleaching, reducing power, metal chelating ability and total phenolic content. Crude extract and polar fractions showed stronger antioxidant capacity and contained very high level of total phenolics. They exhibited strong DPPH radical scavenging, nitric oxide scavenging and reducing power, medium -carotene bleaching and poor metal chelating capacity. Positive correlation obtained between total phenolic content and antioxidant capacity assays, indicated the contribution of phenolics toards antioxidant capacity.