Clarification of the mechanism of menaquinone-4 formation from naphthoquinone ring and isoprenoid side-chain in major tissues of rats

阐明大鼠主要组织中萘醌环和类异戊二烯侧链形成甲基萘醌-4 的机制

基本信息

批准号：
07660150
负责人：
KOMAI Michio
金额：
$ 1.47万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

Phylloquinone (PK=VK_1) and the menaquinones (MK-n, VK_2) are naturally occurring forms of vitamin K.Most of the menaquinone series are synthesized microbiologically, but we have reported elsewhere that menaquinone-4 (MK-4) is an usual in being synthesized by the conversion of ingested phylloquinone or menadione (VK_3) in the major tissues of germ-free rats or mice (which lack an intestinal microflora). The present research was undertaken to clarify the mechanism of MK-4 formation from naphthoquinone ring and isoprenoid side-chain in major tissues of rats.In the first experiment, the distribution of phylloquinone and MK-4 in various tissues were assessed after the oral administration of phylloquinone. Wistar rats were fed a vitamin-K-deficient diet for 9 days, fasted for 24h and then given phylloquinoe orally at 4mg/kg body weight. Rats were sacrificed 0,6,12, and 24h after the administration, and an analysis was made of the vitamin K analogues in the plasma, liver, brain, testis, kidn … More ey, and spleen. The phylloquinone concentration in plasma and the tissues reached a peak 6h after the oral administration of phylloquinone. By contrast, the concentration of MK-4 peaked in the liver, plasma, kidney, and spleen at 12h, and in brain and testis at 24h. This data suggests that the ingested phylloquinone was probably converted into MK-4 within the tissues themselves, rather than via hepatic metabolism. The evidence for this is that, after phylloquinone administration, (i) in each of the tissues, the MK-4 concentration increased much more slowly than that of phylloquinone, and (ii) the MK-4 concentration in the plasma and liver reached only much lower levels than those seen in other tissues.In the second and third experiments in which the labeled phylloquinone was used, it was shown that [side-chain-^3H]-label of phylloquinone was not incorporated into the side-chain of MK-4, however, the radioacitivity originated from the [ring-8]-^<14>C-phylloquinone was detected in the MK-4 fraction of various tissues. These phenomena indicate that the isoprenoid side-chain of phylloquinone once separate from its maphthoquinone ring, then it may be replaced by other isoprenoid side chain such as geranyl-geranyl group within each tissue, and suggest that K_3 must be detected in the midst of the reaction. Actually, the radioactivity from [ring-8]-^<14>C-phylloquinone was clearly detected in the K_3 fraction of heart. In the final experiment, the converted MK-4 fraction was collected and purified, then the identification of estimated MK-4 molecule was undertaken by the high-resolution mass spectrometry, and it was finally identified as MK-4. Less

拟南芥（PK = vk_1）和甲氯酮（MK-N，VK_2）是自然发生的维生素K。大多数Menaquinone系列序列是微生物学上合成的，但我们在其他地方都报告说，Menaquinone-4（MK-4）是由Menaquinone-4（Mk-4）是一种经常通过的ph，或者是由MEN phs phs phs phseyl consance and and phseyl consance and and and and phsion phorne consoine consoine and phine consection。（VK_3）在无菌大鼠或小鼠的主要组织中（缺乏肠道菌群）。进行了本研究，以阐明大鼠主要组织中萘醌环和类异丙链链的MK-4形成的机制。在第一个实验中，在口服给药后，评估了phylloquinone和MK-4在各种组织中的分布。将wistar大鼠喂食维生素-K缺乏饮食9天，禁食24小时，然后以4mg/kg体重进行口服phylloquinoe。在给药后处死大鼠0,6,12和24小时，并对血浆，肝脏，脑，睾丸，睾丸，绑带的维生素K类似物进行了分析。口服phylloquinone后，血浆中的叶氟喹酮浓度达到了峰值6H。相比之下，MK-4的浓度在肝脏，等离子体，肾脏和囊中达到12小时的峰值，在24小时时在大脑和睾丸中达到峰值。该数据表明，摄入的phylloquinone可能在组织本身内转化为MK-4，而不是通过肝肝代谢。这样做的证据是，在每个组织中给药后（i），MK-4的浓度比苯二醌的浓度慢得多，以及（ii）血浆和肝脏中的MK-4浓度仅比其他组织中所见的phylose phylloquin，该水平仅比其他组织中的水平低得多。 [侧链 - ^3H] - 未掺入MK-4的侧链中，但是，在各种组织的MK-4馏分中检测到[RING-8] - ^<14> c-phylloquinone的侧链。这些现象表明，腓洛宁酮的异丙酮侧链曾经与其地形喹酮环分开，然后可以被其他类异戊二烯侧链（例如每种组织中的其他类异丙基侧链）取代，并建议必须在反应的中间检测到K_3。实际上，在心脏的K_3级分中清楚地检测到[Ring-8] - ^<14> c-phylloquinone的放射性。在最后的实验中，收集了转化后的MK-4馏分并纯化，然后通过高分辨率质谱进行了估计的MK-4分子的鉴定，并最终被鉴定为MK-4。较少的