Sivesind Evan, Seguin Philippe
Department of Plant Science, McGill University, Macdonald Campus, 21111 Lakeshore Road, Sainte-Anne-de-Bellevue, Québec H9X 3V9, Canada.
J Agric Food Chem. 2005 Aug 10;53(16):6397-402. doi: 10.1021/jf0507487.
Red clover (Trifolium pratense L.) contains isoflavones that are of interest because of their benefits for human health as well as their adverse effects on the fertility of farm animals. A series of field experiments was conducted in Sainte-Anne-de-Bellevue, QC, Canada, to determine the effects of the environment, cultivar, plant maturity, plant part, and preservation method on the concentration of the two predominant isoflavones in red clover, formononetin and biochanin A. In a multi-year, multisite trial, the total isoflavone concentration in 10 cultivars ranged between 8,923 and 12,753 microg g(-1) of DM averaged across sites, harvests, and years. Despite strong environmental effects, the cultivar "Start" consistently had the lowest isoflavone concentrations, with few differences observed among other cultivars. Across stages of maturity, leaves were found to have the highest isoflavone concentration followed by stems and inflorescences (11,970, 4,896, and 3,297 microg g(-1) of DM, respectively). Changes in isoflavone concentrations with increasing maturity varied depending on the plant part. Overall, highest isoflavone concentrations were found in leaves and stems during the vegetative stages, with the formononetin concentration declining until plants initiated flowering, especially in stems, with concentrations then stabilized in both parts. Upon initiation, inflorescences contained similar isoflavone concentrations than leaves, but concentrations decreased rapidly during flower development to fall even below those observed in stems. Inflorescences then had isoflavone concentrations that were as much as 11 times lower than leaves. Fresh herbage contained higher formononetin and total isoflavone concentrations than did silage and hay (14,464, 12,200, and 11,604 microg g(-1) of DM, respectively). The isoflavone concentration in field-grown red clover is thus high but can be affected by a range of agronomic factors.
红三叶草（Trifolium pratense L.）含有异黄酮，由于其对人体健康有益以及对农场动物繁殖力有不良影响而备受关注。在加拿大魁北克省圣安妮德贝尔维尤进行了一系列田间试验，以确定环境、品种、植株成熟度、植株部位和保存方法对红三叶草中两种主要异黄酮（芒柄花黄素和鹰嘴豆芽素A）浓度的影响。在一项多年、多地试验中，10个品种的总异黄酮浓度在各地点、收获期和年份的平均值为8923至12753微克/克干物质。尽管环境影响很大，但“Start”品种的异黄酮浓度始终最低，其他品种之间差异不大。在整个成熟阶段，发现叶片中的异黄酮浓度最高，其次是茎和花序（分别为11970、4896和3297微克/克干物质）。异黄酮浓度随成熟度增加的变化因植株部位而异。总体而言，在营养生长阶段，叶片和茎中的异黄酮浓度最高，芒柄花黄素浓度在植株开始开花前下降，尤其是在茎中，之后在两个部位都趋于稳定。开始时，花序中的异黄酮浓度与叶片相似，但在花发育过程中迅速下降，甚至低于茎中的浓度。花序中的异黄酮浓度最终比叶片低多达11倍。新鲜牧草中的芒柄花黄素和总异黄酮浓度高于青贮饲料和干草（分别为14464、12200和11604微克/克干物质）。因此，田间种植的红三叶草中的异黄酮浓度很高，但会受到一系列农艺因素的影响。
