| The phytochemical substances, glucosinolates (GS) and flavonoids were identified in different Chinese kale cultivars. The glucosinolates and flavonoids contents at different seasons and the contents in various organs(inflorescences, stems, leaves, leave stalks) were measured. The flavonoids concentrations in various vegetables were also determined in this study.Glucosinolates were quantified by reverse phase high performance liquid chromatography using ammonium acetate, ammonium acetate/methanol as eluents in a gradient program. Identification of glucosinolates was done by comparison of their retention times with that of standards. In addition, peak identity was confirmed by photodiode array detector (DAD), electrospray ionization mass spectrometry (ESI/MS) and MS/MS. 7 glucosinolates were found in Chinese kale: 2-hydoxylbut-3-enyl GS (Progoitrin, PRO), 4-methylsulfinylbutyl GS (Glucoraphanin, RAA), but-3-enyl GS (Gluconapin, NAP), 4-hydroxyindol-3-ylmethyl GS (4-Hydroxyglucobrassicin, 40H), indol-3-ylmethyl GS (Glucobrass-icin, GBC), 4-methoxyindol-3-ylmethyl GS (4-Methoxyglucobrassicin, 4ME), l-Methoxyindol-3-methyl GS (Neoglucobrassicin, NEO). NAP was predominant GS in all the cultivars, followed by RAA, GBC, NEO, and 40H, 4ME were only found in small amounts. Differences was observed in total GS and individual GS content in various Chinese kale cultivars. The total GS contents were much higher in JL74, JL59, JL73, JL68, JL52, JL56 than the other cultivars, RAA, a substance which can be breakdown to sulforaphanin, with high activity against carcinogen, was found in considerable amounts in JL74, JL59, JL56. Cultivars harvested in the open air in autumn have both higher total GS and individual GS than the same cultivars cultured in the plastic tunnels in spring. GS contents depend on the plant part, and the highest level was found in inflorescences followed by stems, leave stalks and leaves.Flavonoids were identified by comparison of the retention time of samples withthat of standards. The UV/VS (detected at 370nm) and DAD (scan wave length from 190nm to 400nm) detector was used for peak identity confirmation. The resulting flavonoids were quantified by reverse phase HPLC on a Nova-Pak C18 column using acetonitrile/phosphate buffer (25/75v/v, pH2.4) at 30?C. External standards, myricetin, luteolin, quercetin, apigenin, kaempferol were used to confirm the flavonoids contents. Quercetin and kaemferol were the major flavonoids in Chinese kale. The flavonoids content varied with different cultivars, the higher level were found in JL73, JL72, JL68, JL62. Total flavonoids concentration of Chinese kale cultivars harvested in different season and the content in various edible parts were also tested in this study, the results showed that cultivars planted in the open air in autumn have both higher total and individual flavonoids contents than the cultivars cultured in plastic tunnel in spring, and leaves have more total and individual flavonoids contents than inflorescence, stems, and leave stalks. The flavonoids contents in 15 vegetables commonly consumed in Beijing were also tested in winter season. The major flavonoids were quercetin and kaemferol, whereas myricetin was not found. In onion bulbs and tender pod peas only quercetin was found, and red onion possess higher quercetin content than yellow onion. Quercetin, kaempferol, luteolin, was found in celery leaves which also have both higher total and individual flavonoids content than celery hearts and stalks. No flavonoids was detected in Yellow gallic seedlings, while green garlic seedlings contained quercitin and kaempferol. Small amout of quercetin was found in Asparagus lettuce leaves but not in stems. |
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