Distribution of glucosinolates in ornamental cabbage and kale cultivars

Glucosinolate concentrations were measured in seven ornamental cabbage and six ornamental kale (Brassica oleracea var. acephala) cultivars. Fifteen glucosinolates were detected in varying concentrations, but only four (progoitrin, sinigrin, glucoraphanin and glucobrassicin) were found in concentrations greater than 0.5 μmol g^-1 dry weight. In general, total glucosinolates in ornamental cabbage were about 35% higher than in ornamental kale. Differences in total glucosinolates were also observed within each Brassica group. In cabbage, total glucosinolates were significantly higher in 'Osaka Pink', 'Osaka Red', 'Pigeon Red' and 'Tokyo Pink' than in 'Osaka White' or 'Tokyo White', while total glucosinolates in 'Tokyo Red' was not significantly different from the other five cultivars. In kale, total glucosinolate concentration was highest (17.16 μmol g^-1 dry weight) in 'Coral Prince' and lowest (6.8 μmol g^-1 dry weight) in 'Sparrow White'. Ornamental cabbage cultivars contained higher glucoraphanin, followed by sinigrin, progoitrin and glucobrassicin, while ornamental kale cultivars contained about the same concentrations of glucoraphanin, sinigrin and glucobrassicin, except 'Coral Prince' which contained three- to nine-fold higher glucoraphanin than the other five kale cultivars. The presence of higher concentrations of glucoraphanin in ornamental cabbage and ornamental kale warrant further investigation into their potential use as breeding stocks to enhance the level of this important phytochemicals in edible cabbage and kale.