Li Xian, Kushad Mosbah M
Department of Natural Resources and Environmental Sciences, University of Illinois-Urbana/Champaign, 1201 West Gregory Drive, Urbana, Illinois 61801, USA.
J Agric Food Chem. 2004 Nov 17;52(23):6950-5. doi: 10.1021/jf0401827.
Fully developed horseradish (Armoracia rusticana Gaertn., Mey., & Scherb.) roots from 27 accessions and leaves from a subset of 9 accessions were evaluated for glucosinolates and myrosinase enzyme activity. Eight different glucosinolates were detected (based on HPLC retention times as desulfoglucosinolates) in both root and leaf tissues. The sum of these glucosinolates, referred to as total, ranged from 2 to 296 micromol g(-1) of dry weight (DW) in both tissues. Four glucosinolates (sinigrin, glucobrassicin, neoglucobrassicin, and gluconasturtiin) were detected in major quantities. In fully developed roots, sinigrin concentration represented approximately 83%, gluconasturtiin approximately 11%, and glucobrassicin approximately 1% of the total glucosinolates. Approximately the same proportions of individual glucosinolates appeared in fully developed leaves, except that glucobrassicin was substituted by neoglucobrassicin and gluconasturtiin concentration was significantly lower (<1%). At least four other glucosinolates were detected in very small quantities (<1%) in both roots and leaves. Myrosinase (beta-thioglucoside glucohydrolase, EC 3.2.3.1) is the enzyme responsible for the hydrolysis of the parent glucosinolates into biologically active products. Very little is known about myrosinase activity and the correlation of its activity to total and individual glucosinolates in plant tissues. Significant differences in myrosinase activity were detected between the roots and leaves, ranging from 1.2 to 57.1 units g(-1) of DW. Data showed no correlation between myrosinase activity and total and/or individual glucosinolates in the roots. However, in the leaves, significant correlations were found between myrosinase activity and total glucosinolates (0.78 at P = 0.01) and between myrosinase activity and sinigrin (0.80 at P = 0.01). Glucosinolates content and myrosinase activity were also correlated in young and fully developed roots and leaves and during tissue crushing. Glucobrassicin concentration in the roots and neoglucobrassicin concentration in the leaves were significantly higher in young than in fully developed tissue. Crushing of the tissue resulted in rapid hydrolysis of sinigrin and glucobrassicin, as expected, from the presence of myrosinase. Likewise, myrosinase activity declined rapidly after crushing, perhaps due to inactivation by the reaction products and/or the depletion of its substrates.
对27个品种的成熟辣根（Armoracia rusticana Gaertn., Mey., & Scherb.）根以及9个品种的叶进行了硫代葡萄糖苷和黑芥子酶活性评估。在根和叶组织中均检测到8种不同的硫代葡萄糖苷（基于高效液相色谱保留时间作为脱硫硫代葡萄糖苷）。这些硫代葡萄糖苷的总和，即总量，在两种组织中的干重（DW）范围为2至296微摩尔/克。检测到4种主要的硫代葡萄糖苷（黑芥子硫苷、吲哚 - 3 - 甲基硫苷、新吲哚 - 3 - 甲基硫苷和葡萄糖水苏碱）。在成熟根中，黑芥子硫苷浓度约占总硫代葡萄糖苷的83%，葡萄糖水苏碱约占11%，吲哚 - 3 - 甲基硫苷约占1%。在成熟叶中，各硫代葡萄糖苷的比例大致相同，只是吲哚 - 3 - 甲基硫苷被新吲哚 - 3 - 甲基硫苷取代，且葡萄糖水苏碱浓度显著降低（<1%）。在根和叶中还检测到至少4种其他硫代葡萄糖苷，含量极少（<1%）。黑芥子酶（β - 硫代葡萄糖苷葡萄糖水解酶，EC 3.2.3.1）是负责将母体硫代葡萄糖苷水解为生物活性产物的酶。关于黑芥子酶活性及其在植物组织中与总硫代葡萄糖苷和单个硫代葡萄糖苷的相关性，人们了解甚少。根和叶之间的黑芥子酶活性存在显著差异，范围为1.2至57.1单位/克干重。数据表明，根中黑芥子酶活性与总硫代葡萄糖苷和/或单个硫代葡萄糖苷之间无相关性。然而，在叶中，黑芥子酶活性与总硫代葡萄糖苷之间存在显著相关性（P = 0.01时，r = 0.78），与黑芥子硫苷之间也存在显著相关性（P = 0.01时，r = 0.80）。在幼根和成熟根以及叶中，硫代葡萄糖苷含量和黑芥子酶活性在组织研磨过程中也具有相关性。幼根中的吲哚 - 3 - 甲基硫苷浓度和叶中的新吲哚 - 3 - 甲基硫苷浓度显著高于成熟组织。正如预期的那样，由于存在黑芥子酶，组织研磨导致黑芥子硫苷和吲哚 - 3 - 甲基硫苷迅速水解。同样，研磨后黑芥子酶活性迅速下降，可能是由于反应产物使其失活和/或底物耗尽所致。
