THE ANTIOXIDATIVE PROPERTIES OF WHITE CABBAGE (BRASSICA OLERACEA VAR. CAPITATA F. ALBA) FRESH AND SUBMITTED TO CULINARY PROCESSING

Abstract

ABSTRACT White cabbage, fresh or fermented belongs to major dietary ingredients in Central Europe. Here we concentrated on antioxidative properties of cabbage since such activities are believed to prevent undesirable effects in human organism. These properties were assessed for juices in cell-free system by antioxidant capacity, in HT29 cells by protection against DNA oxidation, and stimulation of GSTs and DNA repair. Although cabbage does not possess high antioxidative potential compared with other plantborne foods, it may provide a very effective antioxidative barrier especially if culinary processing caused the release of antioxidants. All juices increased GST activities to various degree regardless of cabbage origin or year of cultivation and stimulated DNA repair enzymes. Cabbage juices also prevented DNA damage when applied to HT29 cells concomitantly with H2O2; however, no protective effect was seen after prolonged (24 h) incubation with these juices prior to ROS exposure. Interestingly, in this tumor cell line, both cabbage juices displayed moderate inhibitory effect on cell growth and induced DNA fragmentation readily detectable by comet assay. PRACTICAL APPLICATIONS The presented research demonstrated different antioxidative activities for cabbage juices, that is, the actual food component, at dietarily relevant concentrations, which allows one to draw practical conclusions. Technologically, the direct ability to scavenge ROS, especially its increase upon heat processing, suggests that cabbage may protect other food components against undesirable oxidative changes. In another study, we confirmed that animal fats low in natural antioxidants, therefore very liable to thermooxidative spoilage, are effectively protected by cabbage phytocomplex. Biologically, the ability to induce in human cells a variety of protective mechanisms at low concentrations implies that the consumption of this vegetable should be recommended. However, our results also demonstrated dangers of overdosing. The exposure to cabbage juices prior to ROS strongly sensitized cells to oxidative stress and in this context, the use of concentrated extracts from cruciferous vegetables, offered by several producers as dietary supplements, seems to require more careful consideration.