The antioxidant activity of extracts from Capparis spinosa L. buds was evaluated using different in vitro tests: ascorbate/Fe(2+)-mediated lipid peroxidation of microsomes from rat liver; bleaching of 1,1-diphenyl-2-picryl-hydrazyl radical; and autoxidation of Fe(2+) ion in the presence of bathophenanthroline disulfonate. The methanolic extract showed strong activities in all of these in vitro tests. The amount of total phenols was determined in the methanolic extract. In addition, the level of rutin was calculated as 0.39% (w/w) by HPLC analysis. Our findings indicate the following: (a) the antioxidant efficiency of the methanolic extract may be attributed to its phenolic content; and (b) the antioxidant activity of the methanolic extract was maintained after removal of glucosinolates, confirming that these compounds do not interfere with the antioxidant properties of the extract. The results obtained from this study exalt the nutritional value of the flowering buds (capers) which are widely used as a source of flavor.

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Several nonsymmetric polychlorinated biphenyl (PCB) congeners form atropisomers due to steric hindrance of free rotation around the phenyl-phenyl bond. It is evident from the literature that both chiral PCB congeners and their atropisomeric methylsulfonyl-PCB metabolites, formed in higher animals and in humans, are present in biota as nonracemic mixtures. Chiral methylsulfonyl-PCBs are strongly dominated by one of the atropisomers in mammalian tissues. The aim of the present study is to examine enantioselective metabolism, retention, and excretion of 2,2',3,3',4,6'-hexachlorobiphenyl (CB-132) in rat by administration of a CB-132 racemate and pure atropisomers. Chemical analysis of liver, lung, and adipose tissue from the rats showed a strong retention of one of the CB-132 atropisomers and a similar, but even more pronounced, accumulation of one of the atropisomers of the meta- and para-methylsulfonyl-substituted CB-132 metabolites in these tissues. Metabolites with R structures were predominately formed from one of the atropisomers of CB-132. The slower metabolism of the other atropisomer of CB-132 and its pronounced excretion in feces suggest an enantioselective metabolism. The results indicate enantio-selective formation of the methylsulfonyl-CB132 metabolites and confirm the critical role of stereochemistry of chemicals for their metabolism.

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