Separation and identification of glucosinolates of vegetable turnip rape by LC/APCI-MS and comparison of their contents in ten cultivars of vegetableturnip rape (Brassica rapa L.)

Eight major glucosinolates (GSLs) were identified in ten cultivars of veget able turnip rape (Brassica rapa L,) by LC/APCI-MS. The GSLs indentified inc luded five alkenyl GSLs (progoitrin, glucoraphanin, sinigrin, gluconapin, a nd glucobrassicanapin), two indolyl GSLs (4-hydroxyglucobrassicin and gluco brassicin), and one aromatic GSL (gluconasturtiin). The total GSL content i n the ten cultivars ranged from 36 to 187 mmol kg(-1) DW. The content of in dolyl glucosinolate (GSL) ranged widely from 0.4 to 8.2 mmol kg(-1) DW, whi ch accounted for 0.5 to 10.2%, respectively, of the total GSL content, Alth ough the total GSL content was affected by the harvest dates, the proportio n of individual GSLs did not change significantly, Furthermore, the proport ion of the individual GSL content between edible parts and seeds in vegetab le turnip rape varied considerably, especially for gluconapin and glucobras sicanapin. Among them, the sum of the contents of gluconapin and glucobrass icanapin accounted for more than 65% of the total GSL content in nine veget able turnip rape cultivars except for cv, Husanohana in which the percentag es of gluconapin and glucobrassicanapin of total GSL was less than 53%, The proportion of progoitrin as a percentage of the total GSL content was mark ably different between vegetable turnip rape and rapeseed (B, napus L,), na mely 1 and 48%, respectively. As a result, it was difficult to predict the individual GSL content in edible parts compare to those in the seeds analyz ed.