PIERIS BRASSICAE FED WITH BRASSICA OLERACEA VAR. COSTATA AND BRASSICA OLERACEA VAR. ACEPHALA AS SOURCE OF BIOACTIVE COMPOUNDS

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Kale extract increases glutathione levels in V79 cells, but does not protect them against acute toxicity induced by hydrogen peroxide

Publication . Fernandes, Fátima; Sousa, Carla; Ferreres, Frederico; Valentão, Patrícia; Remião, Fernando; Pereira, J.A.; Andrade, Paula B.

This study aims to evaluate the antioxidant potential of extracts of Brassica oleracea L. var. acephala DC. (kale) and several materials of Pieris brassicae L., a common pest of Brassica cultures using a cellular model with hamster lung fibroblast (V79 cells) under quiescent conditions and subjected to H₂O₂ induced oxidative stress. Cytotoxicity was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and glutathione was determined by the 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB)-oxidized glutathione (GSSG) reductase recycling assay. The phenolic composition of the extracts was also established by HPLC-DAD. They presented acylated and non acylated flavonoid glycosides, some of them sulfated, and hydroxycinnamic acyl gentiobiosides. All extracts were cytotoxic by themselves at high concentrations and failed to protect V79 cells against H₂O₂ acute toxicity. No relationship between phenolic composition and cytotoxicity of the extracts was found. Rather, a significant increase in glutathione was observed in cells exposed to kale extract, which contained the highest amount and variety of flavonoids. It can be concluded that although flavonoids-rich extracts have the ability to increase cellular antioxidant defenses, the use of extracts of kale and P. brassicae materials by pharmaceutical or food industries, may constitute an insult to health, especially to debilitated individuals, if high doses are consumed.

2012Journal article

Open access

Metabolic and bioactivity insights into Brassica oleracea var. acephala

Publication . Ferreres, Frederico; Fernandes, Fátima; Sousa, Carla; Valentão, Patrícia; Pereira, J.A.; Andrade, Paula B.

Seeds of Brassica oleracea var. acephala (kale) were analyzed by HPLC/UV-PAD/MSn-ESI. Several phenolic acids and flavonol derivatives were identified. The seeds of this B. oleracea variety exhibited more flavonol derivatives than those of tronchuda cabbage (Brassica oleracea var. costata), also characterized in this paper. Quercetin and isorhamnetin derivatives were found only in kale seeds. Oxalic, aconitic, citric, pyruvic, malic, quinic, shikimic, and fumaric acids were the organic acids present in these matrices, malic acid being predominant in kale and citric acid in tronchuda cabbage seeds. Acetylcholinesterase (AChE) inhibitory activity was determined in aqueous extracts from both seeds. Kale leaves and butterflies, larvae, and excrements of Pieris brassicae reared on kale were also evaluated. Kale seeds were the most effective AChE inhibitor, followed by tronchuda cabbage seeds and kale leaves. With regard to P. brassicae material, excrements exhibited stronger inhibitory capacity. These results may be explained by the presence of sinapine, an analogue of acetylcholine, only in seed materials. A strong concentration-dependent antioxidant capacity against DPPH, nitric oxide, and superoxide radicals was observed for kale seeds.

2009Journal article

Restricted access