代谢
新甜素(Neotame)在其二甲丁基侧链的1位上标记了碳-14,并在同一侧链的2个末端甲基上标记了碳-13。志愿者在水中共服用了相当于0.25毫克/千克的标记试验物质的单剂量,这相当于将1升饮料加甜所需的新甜素量。新甜素被迅速但不完全吸收,并且被迅速排出。平均来说,给药的放射性物质中有98%在尿液和粪便中被回收,大多数在给药后72小时内。新甜素的平均血浆浓度在0.4小时达到峰值...并且以0.6小时的半衰期下降。新甜素的主要代谢物是通过甲基酯基水解形成的去酯新甜素。这种代谢物的平均血浆浓度在1小时达到峰值...并且比新甜素浓度高出大约2.5倍,以1.5小时的半衰期下降。去酯新甜素平均约占排泄剂量的80%。还有两种其他代谢物在剂量中占1%以上。其中一种,平均约占剂量的4.9%,在粪便中被发现,被鉴定为N-(3,3-二甲基丁基)-L-天冬氨酸。另一种代谢物在尿液中,通过LC/MS/MS、NMR和原始合成被鉴定为3,3-二甲基丁酸 carnitine 酯。所有在剂量中占1%或更多的新甜素代谢物都在安全性研究中使用的物种中被发现,这证实了这些代谢物的安全性。
... Neotame was labelled with Carbon-14 at the 1-position in the dimethylbutyl side chain and with Carbon-13 in the 2 terminal methyl groups of the same side chain. ... Volunteers ingested a single dose of the labelled test substance in water at a level approximately equivalent to 0.25 mg/kg, which corresponds to the amount of neotame needed to sweeten 1 L of beverage. Neotame was rapidly, but incompletely absorbed and rapidly excreted. A mean of 98% of the administered radioactivity was recovered in urine and feces, mostly within 72 hours of dosing. Mean plasma concentrations of neotame peaked at 0.4 hr ... and declined with a half-life of 0.6 hr. The major metabolite of neotame was de-esterified neotame formed by hydrolysis of the methyl ester group. Mean plasma concentrations of this metabolite peaked at 1 hr ... /and/ were approximately 2.5 times higher than neotame concentrations and declined with a half-life of 1.5 hr. De-esterified neotame represented a mean of approximately 80% of the excreted dose. Two other metabolites were detected at greater than 1% of the dose. One, that was a mean of about 4.9% of the dose, was found in the feces and was identified as N-(3, 3 dimethylbutyl)-L aspartic acid. The other metabolite was in urine and was identified by LC/MS/MS, NMR and original synthesis as a carnitine ester of 3, 3-dimethylbutanoic acid. All metabolites of neotame present at 1% or greater of the dose have been shown to occur in the species used in safety studies, confirming the safety of these metabolites.
来源:Hazardous Substances Data Bank (HSDB)