Flåøyen A, Wilkins A L
Department of Reproduction and Forensic Medicine, Norwegian College of Veterinary Medicine, Oslo, Norway.
Vet Res Commun. 1997 Jul;21(5):335-45. doi: 10.1023/a:1005860220462.
One sheep was dosed over 4 consecutive days with 2.1 kg of leaves and flower stems of Narthecium ossifragum before it was killed. Sarsasapogenin and smilagenin glycosides, in the ratio 9:1, were the dominant saponins present in the dosed plant material. GC-MS analyses of the free and conjugated sapogenin content of samples recovered from the sheep identified three distinct regions of metabolic activity. In the first metabolic region, in the rumen and omasum, the ingested plant saponins were hydrolysed to the parent sapogenins, before being oxidized at C-3 and reduced to give the epi analogues of the ingested sapogenins. The second metabolic region consisted of the duodenum, jejunum, the liver and associated ducts. Sapogenins appear to be absorbed in the jejunum and may be transported via the portal vein to the liver, where 3 alpha-OH-5 beta-H sapogenins (epismilagenin and episarsasapogenin), but not 3 beta-OH-5 alpha-H sapogenins (smilagenin and sarsasapogenin), are conjugated and excreted into the bile as episarsasapogenin and epismilagenin conjugates in the ratio 4:1. In the third metabolic region, in the caecum and the colon, the epi-sapogenin conjugates were hydrolysed to free epi-sapogenins. The absence of free and/or conjugated sapogenins in urine, collected 24 h after dosing commenced, indicates that saponins and their metabolites are not likely to be implicated in the kidney disease occurring in ruminants ingesting N. ossifragum.
在处死一只绵羊前,连续4天给它投喂2.1千克骨碎补(Narthecium ossifragum)的叶子和花茎。给药的植物材料中,以9:1比例存在的菝葜皂苷元和薯蓣皂苷元糖苷是主要的皂苷。对从绵羊体内回收的样本中游离和结合皂苷元含量进行的气相色谱-质谱分析确定了三个不同的代谢活性区域。在第一个代谢区域,即瘤胃和网胃中,摄入的植物皂苷被水解为母体皂苷元,然后在C-3位被氧化并还原,生成摄入皂苷元的表异构体。第二个代谢区域由十二指肠、空肠、肝脏及相关导管组成。皂苷元似乎在空肠被吸收,并可能通过门静脉输送到肝脏,在肝脏中,3α-羟基-5β-H皂苷元(表薯蓣皂苷元和表菝葜皂苷元),而非3β-羟基-5α-H皂苷元(薯蓣皂苷元和菝葜皂苷元),会被结合,并以4:1的比例作为表菝葜皂苷元和表薯蓣皂苷元结合物排泄到胆汁中。在第三个代谢区域,即盲肠和结肠中,表皂苷元结合物被水解为游离的表皂苷元。给药开始24小时后收集的尿液中没有游离和/或结合的皂苷元,这表明皂苷及其代谢产物不太可能与摄入骨碎补的反刍动物发生的肾脏疾病有关。