Antioxidant, antiinflammatory and antiinvasive activities of biopolyphenolics

A large number of polyphenolic and heterocyclic compounds, i.e. 4-methylcoumarins, 4-methylthionocoumarins, xanthones, pyrazoles, pyrazolylacrylonitriles, flavones and isoflavones have been tested for their antioxidant activity towards NADPH-catalysed liver-microsomal lipid peroxidation with a view to establish their structure-activity relationship. Inhibition of microsomal lipid peroxidation by 7,8-dihydroxy-4-methylcoumarin (DHMC, 2) and 7,8-diacetoxy-4-methylcoumarin (DAMC, 3) was intriguing. We also found that dihydroxy and diacetoxy derivatives of 4-methylthionocoumarin were more potent in comparison to the corresponding coumarin derivatives in inhibiting TNF-α induced expression of ICAM-1. The effect of nine different xanthones has been examined on the modulation of cytokine-induced expression of ICAM-1 in human endothelial cells. 1,4-Dihydroxyxanthone (10) showed enhanced antioxidant activity as well as the inhibition of the expression of cell adhesion molecules, such as ICAM-1, VCAM-1 and E-selectin on endothelial cells in a concentration and time dependent manner. Antioxidant activity of different pyrazoles and pyrazolylacrylonitriles and antiinvasive activity of flavones and isoflavones against solid tumors have also been studied

Synthesis of macromolecular systems via lipase catalyzed biocatalytic reactions: applications and future perspectives

Enzymes, being remarkable catalysts, are capable of accepting a wide range of complex molecules as substrates and catalyze a variety of reactions with a high degree of chemo-, stereo- and regioselectivity in most of the reactions. Biocatalysis can be used in both simple and complex chemical transformations without the need for tedious protection and deprotection chemistry that is very common in traditional organic synthesis. This current review highlights the applicability of one class of biocatalysts viz. ‘‘lipases’’ in synthetic transformations, the resolution of pharmaceutically important small molecules including polyphenols, amides, nucleosides and their precursors, the development of macromolecular systems (and their applications as drug/gene carriers), flame retardants, polymeric antioxidants and nanocrystalline solar cells, etc

Biocatalytic acylation studies on novel 3-aryl-3-hydroxymethyl-2, 3-dihydro-4H-1- benzopyran-4-ones

1501-1510(±)-3-Aryl-3-hydroxymethyl-2,3-dihydro-4H-1- benzopyran-4-ones have been synthesized in four steps starting with the coupling of resorcinol with corresponding phenylacetic acid leading to the formation of 2,4-dihydroxyphenyl aryl ketones, which upon monomethylation/benzylation and hydroxymethylation afford (±)-hydroxymethylisoflavanones in 65-70% yields. These isoflavanones have been subjected to lipase-catalyzed acylation reactions under different conditions (for optimization) of varying solvents, enzymes and acylating agents. Candida antarctica lipase B in tetrahydrofuran using heptanoic anhydride at 90 ºC is found to be the best reaction protocol for the biocatalytic reaction

<i style="">Candida rugosa </i>lipase-mediated enantioselective acetylation studies on (±)-3-arylmethyl-3-hydroxymethyl-2,3-dihydro-1-benzopyran-4(<i>H</i>)-ones

356-365Candida rugosa lipase, catalyzed enantioselective acetylation reactions have been performed on novel (±)-3-arylmethyl-3-hydroxymethyl-2,3-dihydrobenzopyran-4-ones in diisopropyl ether. The Candida rugosa lipase-catalyzed acetylations exhibit the enantiomeric separation of the racemic compounds 5a-g, the enantioselectivity of the reaction has been found to be highly dependent on the structure of the substrate. The enantiomeric excess (ee) values are determined by 1H NMR spectral analysis of their O-acetylmandelic acid esters and highest enantiomeric excess obtained is 79% in case of 5c