JOBNAME: horts 43#2 2008 PAGE: 1 OUTPUT: February 14 00:39:40 2008 tsp/horts/158649/01912 HORTSCIENCE 43(2):571–574. 2008. iment are shown in Table 1. Seeds were sown on 15 Sept. 2004 and transplanted at the farm of Zhejiang University on 15 Oct. 2004 at a Glucosinolates in Chinese Brassica randomized complete block design with three replicates of 20 plants each. For analysis, the campestris Vegetables: Chinese edible parts of five plants were harvested at commercial maturity stage from each of the Cabbage, Purple Cai-tai, Choysum, three replicates (see Table 1). Edible parts (50 to 200 g of each replicate) were immedi- ately deep frozen with liquid nitrogen, then Pakchoi, and Turnip freeze-dried, and finely ground. The produc- Xinjuan Chen tion period and the climatic conditions under Department of Horticulture, Zhejiang University, Kaixuan Road 268, a field conditions are shown in Table 1. Methods. Samples were prepared accord- Hangzhou 310029, China; and the Institute of Vegetable, Zhejiang ing to the method of Krumbein et al. (2005) Academy of Agriculture Science, Hangzhou 310021, China with slight modification. Duplicates of the 1 freeze-dried powder (0.25 g) in 10-mL glass Zhujun Zhu tubes were preheated for 5 min in 75 °C water Department of Horticulture, Zhejiang University, Kaixuan Road 268, Hangzhou bath. Four milliliters of 70% boiling metha- 310029, China; and the Department of Horticulture, School of Agriculture nol (75 °C) was added and extracted at 75 °C and Food Science, Zhejiang Forestry University, Lin’an 311300, China in a water bath for 10 min. There was 100 mL of 5 mmolÁL–1 sinigrin (Sigma-Aldrich Co., Joska Gerenda´s and Nadine Zimmermann St. Louis) as an internal standard in one of the Institute for Plant Nutrition and Soil Science, University of Kiel, duplicates before extraction. Then 1 mL of –1 Olshausenstr. 40, Kiel 24098, Germany 0.4 molÁL barium acetate was rapidly added and vortexed for several seconds. After cen- Additional index words. Chinese vegetable, glucosinolate, Brassicaceae, composition trifugation at 4000 rpm for 10 min at room temperature, the supernatants were collected Abstract. Brassica campestris vegetables play an important role in the Chinese diet. and the pellets were reextracted twice with The objective of this study was to evaluate the composition and content of glucosinolates 3 mL of 70% boiling methanol (75 °C). Three (GSs)infivespeciesofChineseBrassica campestris vegetables by high-performance liquid supernatants were combined and made into chromatography. The compositions and contents of GSs varied significantly among and a final volume of 10 mL with 70% methanol. within species and cultivars. The contents of total GSs were 100 to 130 mg/100 g fresh Five-milliliter extracts were loaded onto a weight (FW) in turnip (B. rapifera), 50 to 70 mg/100 g FW in purple cai-tai (B. chinensis 1-mL mini-column (JT Baker, Phillipsburg, var. purpurea), and 14 to 35 mg/100 g FW in Chinese cabbage (B. pekinensis), choysum PA) prepared by introducing 500 mLof (B. chinensis var. utilis), and pakchoi (B. chinensis var. communis). In Chinese cabbage, activated DEAE Sephadex A25 (Amersham the predominant individual GSs were glucobrassicin for both cultivars, neoglucobrassi- Biosciences, Uppsala, Sweden) in a vacuum cin only for ‘zaoshuwuhao’, and gluconapin only for ‘zaoshuwuhao’. The predominant processor (JT Baker 12) and allowed to individual GSs were glucobrassicanapin and gluconapin in purple cai-tai and choysum desulphate overnight with aryl sulfatase and gluconapin in pakchoi and turnip. The relative content of total aliphatic GSs was (Sigma-Aldrich Co.). The resultant desulpho 80% to 90% in purple cai-tai and choysum, 60% to 65% in pakchoi and turnip, and 17% (ds)-GS were eluted with 2.5 mL of ultra pure to 50% in Chinese cabbage. The relative content of total indolic GSs was 37% to 75% water produced by Milli-Q system (Millipore in Chinese cabbage, 25% to 27% in pakchoi, and 5% to 17% in purple caitai, choysum, Co., Milford, CT) and stored at –20 °C before and turnip. The relative content of aromatic GSs was 28% to 36% in turnip, 8% to 14% separation by high-performance liquid chro- in Chinese cabbage and pakchoi, and 2% to 4% in choysum and purple cai-tai. These matography (HPLC). results suggest that there are significant genotypic variations in composition and content The elution (20 mL) was analyzed in a of glucosinolates in Chinese Brassica campestris vegetables. Shimadzu HPLC system (LC-10AT pump, CTO-10A column oven, SCL-10A VP sys- tem controller; Shimadzu, Kyoto, Japan) Epidemiological data show that a diet rich tored. To our knowledge, there is limited consisting of an ultraviolet-VIS detector in cruciferous vegetables can reduce the risk information about the comparison of GSs (SPD-10A) set at 229 nm and a prontosil from a number of cancers. Several protection among Chinese Brassica campestris vegeta- ODS2 column (250 · 4 mm, 5 mm; Bischoff, mechanisms for the cancer prevention from bles (He et al., 2000, 2002; Hill et al., 1987; Leonberg, Germany). The mobile phase was cruciferous vegetables have been demon- Lewis and Fenwick, 1988). Therefore, the ultra pure water (A) and acetonitrile (Tedia, strated for the breakdown products of some objective of this study was to compare and Fairfield, OH) (B) in a linear gradient from glucosinolates (GSs) (Mithen et al., 2000). evaluate the composition and content of GSs 0% to 20% B for 32 min, then constant 20% B Some research about glucosinolates has been in edible parts in five species of Chinese for 6 min, and 100% B and 0% B before the done in Brassica crops (Carlson et al., 1987; Brassica vegetables, including Chinese cab- injection of the next sample. The flow rate Krumbein et al., 2005; Mullin and Sahasra- bage (Brassica campestris L. ssp. pekinen- was 1.3 mL min–1. Each individual ds-GS budhe, 1977; Rangkadilok et al., 2002; Rosa sis), choysum (Brassica campestris L. ssp. Á was identified in the HPLC system coupled et al., 1996; Sang et al., 1984). Brassica chinensis var. utilis), purple cai-tai (Brassica with an electrospray ionization ion trap mass campestris vegetables play an important role campestris L. ssp. chinensis var. purpurea), detector system (Agilent 1100 series, Agilent in the Chinese diet, and so their naturally pakchoi (Brassica campestris L. ssp. chinen- Technologies, Palo Alto, CA). The HPLC occurring GSs in edible parts should be moni- sis var. communis), and turnip (Brassica conditions were the same as described previ- campestris L. ssp. rapifera). ously, except the flow rate was 1.0 mLÁmin–1. Received for publication 21 Oct. 2006. Accepted The nebulizer pressure is 60 psi and the flow for publication 10 Feb. 2007. This research was financially supported by Sino- Materials and Methods rate is nitrogen 13 mLÁmin at a drying tem- German Center for Science Promotion [Grant GZ perature of 350 °C. The scan of the masses 051/10 (154)] and the German Research Foundation. Plant materials. Five species of Brassica ranged from 100 m/z to 600 m/z and helium 1To whom reprint requests should be addressed; campestris vegetables were used for this was used as collision gas for the fragmenta- e-mail [email protected] experiment. The materials used in this exper- tion procedure of the isolated compounds in HORTSCIENCE VOL. 43(2) APRIL 2008 571 JOBNAME: horts 43#2 2008 PAGE: 2 OUTPUT: February 14 00:39:42 2008 tsp/horts/158649/01912 Table 1. Species, cultivars, and edible parts of five Brassica campestris vegetables and the production period and climatic conditions. Avg day/night Common name Latin name Cultivars Edible part Production period temp (°C) Chinese cabbage B. campestris ssp. pekinensis Huangyacai Zaoshuwuhao Leaves 15 Sept. to 10 Dec. 21.6/12.7 Purple cai-tai B. campestris ssp. chinensis Wushihong and Xiangyanhong Bolting stems 15 Sept. to 20 Nov. 23.3/14.6 var. purpurea and inflorescences Choysum B. campestris ssp. chinensis Youqing and Sijiu Bolting stems 15 Sept. to 20 Nov. 23.3/14.6 var. utilis and inflorescences Pakchoi B. campestris ssp. chinensis Huqing and Wuyoudong Leaves 15 Sept. to 20 Nov. 23.3/14.6 var. communis Turnip B. campestris ssp. rapifera Wenzhoubai and Wenzhouhong Roots 15 Nov. to 10 Dec. 21.6/12.7 the ion trap. The ionization condition of cap- Aliphatic, indolic, and aromatic gluco- and a mixture of gluconapin and glucoalyssin illary voltage was 4000 V. The mass detec- sinolates. According to the chemical structure, (not separated) were predominant GSs. He tion was recorded in the positive modus. Each different GSs can fall into three principal et al. (2002) also found that the predominant individual GS was identified according to groups comprising the aliphatic group, indolic GSs were gluconapin and progoitrin in choy- their (M + H)+, (M + Na)+,(M+K)+, and (M- group, and aromatic group. Except for the sum and gluconapin and neoglucobrassicin glucosyl + H)+. The amounts of each GS were difference in total GS levels, there was also in pakchoi. Hill et al. (1987) reported that the calculated based on the published ultraviolet considerable variation in the composition and predominant GS was 3-butenyl-GS (gluco- response factors of other ds-GS relative to content of aliphatic, indolic, and aromatic GSs napin) in pakchoi and 3-indolylmethyl-GS ds-sinigrin (European Community, 1990). (Table 2). Turnip and purple caitai had the (glucobrassicin) in Chinese cabbage and both Data analysis. Differences between means highest content of total aliphatic GSs (42 to 3-butenyl-GS and 3-indolylmethyl-GS in turnip. were analyzed by Fisher’s protected least 73 mg/100 g FW); Chinese cabbage and pur- Except the variation in types of predominant significant difference procedure.