Antioxidant Activity, S-alk(en)yl-L-cysteine Sulfoxide and Polyphenol Content in Onion (Allium cepa L.) Cultivars Are Associated with their Genetic Background

Six onion cultivars Bingo, Dormo, Elenka, Elbrus, Spirit, and Sturon grown in the Czech Republic for commercial purposes were analysed to investigate the content of health-promoting compounds. The results showed that at harvest time, cysteine sulfoxide content varied from 32.38 to 44.16 g/kg of dry weight, polyphenol content was between 2.66 and 3.37 g/kg of dry weight, and antioxidant activity ranged from 0.75 to 0.83 g/kg. Cv. Bingo had the highest level of the analysed compounds. The cultivars were concurrently analysed by DNA (microsatellite) markers. Dendrograms based on the chemical composition and DNA analysis were almost identical. This finding confirms the dependence of the secondary metabolite content on onion genotype.