Phytochemical profile of Kohlrabi (Brassica oleracea L. var. gongylodes) cultivated in Italy.

摘要

Kohlrabi (Brassica oleracea L. var. gongylodes) is a native plant from Northern Europe. In the present work, we show a survey on five kohlrabi genotypes (CR13, CR17, CR22, CR25 and CR29) cultivated in Southern Italy. We measured the content of glucosinolates (GLS), total phenols (PC), ascorbic acid (AsA), total anthocyanins (ATH), total carotenoids (CAR) and the antiradical activity on different parts of the plant (skins, stems and leaves). Four GLS were identified in the leaves, i.e., glucoraphanin, glucobrassicin, gluconasturtiin and neo-glucobrassicin. The GLS profile of the stems and leaves were similar. However, stems showed a lower GLS amount and the presence of glucoerucin. The total polyphenols and AsA content was slightly higher in the leaves than in the stems. With regards to ATH, higher values were found in the leaves with respect to the skins, with the exception of CR17. The values of antiradical activity differed depending on the method of measurement. The leaves generally showed higher antiradical activity in terms of DPPH quenching compared to skins and stems, with the exception of CR22 that was highest in stems. On the other hand, leaves and skins had a similar peroxyl radical (ROO.) scavenging capacity, presumably influenced by the presence of anthocyanins, as suggested by the high correlation between ROO scavenging capacity and ATH content (r=0.81). As expected, a significant correlation was found between DPPH quenching and AsA content, and between ROO.and CAR. Interestingly, an unexpected correlation was found between GLS and DPPH determinations, suggesting a possible involvement of GER in the total antiradical activity.