In-vitro evaluation of selected chalcones for antioxidant activity.

Synthetic chalcones (SCs) having different side chains on the 1-(2-Hydroxy-3-(2-hydroxy-cyclohexyl)-4,6 dimethoxy-phenyl(-methanone structure were examined in-vitro for their antioxidant abilities by DPPH (2,2-diphenyl-1-picryl hydrazine) radical scavenging activity, reducing ability, OH radical scavenging activity, inhibition of polyphenol oxidase (PPO) and formation of diene conjugates. Overall, with few exceptions, all the SCs showed moderate biological activity in all the parameters examined. The SCs were found to be reactive towards DPPH radical and had considerable reducing ability. With few exceptions, all the test compounds under study were found to possess moderate to poor OH radical scavenging activity and inhibited PPO significantly and all were found to be effective inhibitors of hydroperoxide formation. These findings suggest that these SCs can be considered as potential antioxidant agents which might be further explored for the design of lead antioxidant drug candidates.

Unsymmetrical diaryl sulfones through palladium-catalyzed coupling of aryl boronic acids and arylsulfonyl chlorides.

[reaction: see text] A simple and efficient method for the synthesis of unsymmetrical diaryl sulfones using the palladium-catalyzed coupling of aryl boronic acids and arylsulfonyl chlorides has been developed. High product yields, a short reaction time, and mild reaction conditions are important features of this method.

Use of sialic acid analogues to define functional groups involved in binding to the influenza virus hemagglutinin.

The initial step of influenza infection is binding of the virus particles via their hemagglutinin to cell-surface sialic acids. This study was initiated to elucidate the functional groups of the nine-carbon sialic acid molecule which interact with the hemagglutinin and contribute to the affinity of this sugar to the protein. In order to address this question, synthetic sialic acid analogues were tested in a virus adsorption inhibition assay for their inhibitory potency. Modifications in three regions of the sialic acid molecule were evaluated: the glycerol side chain (C7-C9), the N-acetyl group at C5, and the carboxy group (C1). In the glycerol side chain, the hydroxy groups at C7 and C8 appear to be important for binding through hydrogen bonds, whereas the hydroxyl at C9 does not appear to be involved. The N-acetyl group is critical for the interaction of sialic acid with the hemagglutinin. The results suggest that its contribution is mediated through hydrophobic interactions of the methyl group. Finally, the orientation of the carboxy group is essential for the binding of sialic acid to the hemagglutinin. The information gained in this study will be useful in developing novel compounds which bind more avidly to the influenza virus hemagglutinin. Such a strategy may contribute to the design of new anti-influenza drugs.