两相溶剂体系酶促合成Aspartame前体的研究

本文报道在两相溶剂体系中利用木瓜蛋白酶催化合成Aspartame前体Z－APM的研究。实验结果表明，木瓜蛋白酶在水-正丁醇两相体系具有较好的催化活性，在底物比（Z－L－Asp：L－PheOMe）为1：1，温度37℃条件下连续反应72h，Z－APM的产率可达62．8％。

Aspartame研究进展

本文综述了Ａｓｐａｒｔａｍｅ的发现、化学性状、特点、甜味机理、安全性、研究情况、合成及其应用。

苯丙氨酸和天冬甜二肽(Aspartame)

苯丙氨酸是1879年Scholze和Barbieri发现的。并且首先从羽扁豆中分离出来。接着1901年Fischer用盐酸水解酪元(Casein)分离制得苯丙氨酸。以后苯丙氨酸的提取、合成和发酵等制备方法陆续出现,并且不断改进和创新。苯丙氨酸纯品白色粉末结晶。呈苦味,

Non-isothermal dehydration kinetic study of aspartame hemihydrate using DSC, TGA and DSC-FTIR microspectroscopy

Three thermal analytical techniques such as differential scanning calorimetry(DSC), thermal gravimetric analysis(TGA) using five heating rates, and DSC-Fourier Transform Infrared(DSCFTIR) microspectroscopy using one heating rate, were used to determine the thermal characteristics and the dehydration process of aspartame(APM) hemihydrate in the solid state.The intramolecular cyclization process of APM anhydrate was also examined. One exothermic and four endothermic peaks were observed in the DSC thermogram of APM hemihydrate,in which the exothermic peak was due to the crystallization of some amorphous APM caused by dehydration process from hemihydrate to anhydride. While four endothermic peaks were corresponded to the evaporation of absorbed water, the dehydration of hemihydrate, the diketopiperazines(DKP) formation via intramolecular cyclization, and the melting of DKP, respectively. The weight loss measured in TGA curve of APM hemihydrate was associated with these endothermic peaks in the DSC thermogram. According to the Flynn–Wall–Ozawa(FWO)model, the activation energy of dehydration process within 100–150 °C was about 218 ± 11 kJ/mol determined by TGA technique. Both the dehydration and DKP formation processes for solid-state APM hemihydrate were markedly evidenced from the thermal-responsive changes in several specific FTIR bands by a single-step DSC-FTIR microspectroscopy.

Acute Impact of Artificial Sweetener, Aspartame on Blood Parameter in Mice

Aspartame (APM) or L-aspartyl-L-phenylalanine methyl ester, a common artificial non-saccharide sweetener used as a sugar substitute in many foods and beverages, has shown some side effects on consumers. The objective of the present study is to study the acute impact of various doses of daily ingestion of APM on blood parameters of mice. Sixty healthy 3 months old male mice raised in the departmental animal house were divided into five groups i.e. the control were fed normal diet and tap water, while other 4 groups (12 each) were daily orally fed with 1 mL of either 40, 500, 1000 or 1500 mg/Kg b wt, dissolved in distilled water using gavages for consecutive 5 weeks. Fresh blood samples collected directly from the heart at dissection were subjected to complete blood counting (CBC) using automated blood analyzer (Cell DYN-1700) in addition to manual differential Leucocytes (WBC) counting. There has been a significant increase (p ≤ 0.01) in WBC counts starting from the lowest dose (40 mg/Kg·b·wt);significant decrease (p ≤ 0.01) in both Hemoglobin percentages (Hb%) and in Lymphocyte percentages (p ≤ 0.004) in comparison with control. It is concluded that the ingestion of aspartame using the above doses has acute impact and is not dose-dependent on blood parameters which could exert further, on the long run, health risks on to other tissues of consumers.

Neurotropic effects of aspartame, stevia and sucralose on memory retention and on the histology of the hippocampus of the ICR mice(Mus musculus)

Objective: To identify the effects of the consumption of non-nutritive sweeteners on memory retention and on the histology of the hippocampus.Methods: In this study, 20 mice were used to determine if there is an effect of consuming the maximum allowable dose of the non-nutritive sweeteners on the memory retention and on the histology of the hippocampus. The mice were distributed into four groups and the treatments were given via oral gavage: Group 1(water), Group 2(aspartame: 1 000 mg/kg), Group 3(stevia: 1 000 mg/kg) and Group 4(sucralose:16 000 mg/kg). Treatments were administered to the different experimental groups for 32 days, after which memory retention was tested using the two-day water maze protocol.After the tests, the mice were sacrificed and the brain was analyzed histologically for neurotrophic effects.Results: Based on the results of the two-day water maze protocol, there were no differences between the non-nutritive sweeteners and the control group. However, stevia showed high cellular apoptosis followed by aspartame, sucralose and control group.Conclusions: There was no significant effect on the memory of the mice. It showed histologically however, that stevia had a significant neurotropic effect compared to the other sweeteners.

Effects of aspartame on hsp70,bcl-2 and bax expression in immune organs of Wistar albino rats

Aspartame, a ＂first generation sweetener＂, is widely used in a variety of foods, beverages, and medicine. The FDA has determined the acceptable daily intake （ADI） value of aspartame to be 50 mg/kg, day, while the JECFA （Joint FAO/WHO Expert Committee on Food Additives） has set this value at 40 mg/kg of body weight/day. Safety issues have been raised about aspartame due to its metabolites, specifically toxicity from methanol and/or its systemic metabolites formaldehyde and formic acid. The immune system is now recognized as a target organ for many xenobiotics, such as drugs and chemicals, which are able to trigger unwanted apoptosis or to alter the regulation of apoptosis. Our previous studies has shown that oral administration of aspartame [40 mg/（kg, day）] or its metabolites for 90 days increased oxidative stress in immune organs of Wistar albino rats. In this present study, we aimed to clarify whether aspartame consumption over a longer period （90-days） has any effect on the expression ofhsp70, bcl- 2 and bax at both mRNA transcript and protein expression levels in immune organs. We observed that oral administration of aspartame for 90 days did not cause any apparent DNA fragmentation in immune organs of aspartame treated animals; however, there was a significant increase in hsp70 expression, apart from significant alteration in bcl-2 and bax at both mRNA transcript and protein expression level in the immune organs of aspartame treated animals compared to controls. Hence, the results indicated that hsp70 levels increased in response to oxidative injury induced by aspartame metabolites; however, these metabolites did not induce apoptosis in the immune organs. Furthermore, detailed analyses are needed to elucidate the precise molecular mechanisms involved in these changes.

Acute effect of aspartame-induced oxidative stress in Wistar albino rat brain

The present study was carried out to investigate the acute effect of aspartame on oxidative stress in the Wistar albino rat brain. We sought to investigate whether acute administration of aspartame （75 mg/kg） could release methanol and induce oxidative stress in the rat brain 24 hours after administration. To mimic human methanol metabolism, methotrexate treated rats were used to study aspartame effects. Wistar strain male albino rats were administered with aspartame orally as a single dose and studied along with controls and methotrexate treated controls. Blood methanol and formate level were estimated after 24 hours and rats were sacrificed and free radical changes were observed in discrete regions by assessing the scavenging enzymes, reduce dglutathione （GSH）, lipid peroxidation and protein thiol levels. There was a significant increase in lipid peroxidation levels, superoxide dismutase activity （SOD）, glutathione peroxidase levels （GPx）, and catalase activity （CAT） with a significant decrease in GSH and protein thiol. Aspartame exposure resulted in detectable methanol even after 24 hours. Methanol and its metabolites may be responsible for the generation of oxidative stress in brain regions. The observed alteration in aspartame fed animals may be due to its metabolite methanol and elevated formate. The elevated free radicals due to methanol induced oxidative stress.

分光光度法测定酶促合成产物Aspartame

一种简便的分光光度法测定 Aspartame,以茚三酮试液为显色剂 ,在 575nm波长处比色 ,在 4～ 2 0 μg/ml浓度范围内 ,Aspartame标准曲线呈线性关系 ,相关系数 r=0 .9992。本文方法用于测定嗜热菌蛋白酶酶促合成产物 Aspartame。

Acute Impact of the Artificial Sweetener Aspartame on the Ultrastructures of Hepatocyte in Mice

A non-saccharide artificial sweetener, aspartame (L-aspartyl-L-phenylalanine methyl ester) is used worldwide as a sugar substitute in many foods and beverages. The objective of this work was to clarify the acute impact of various doses of daily ingestion of Aspartame at the cellular level of the liver tissues in mice. Sixty adult male mice were divided into five groups including control fed normal diet and tap water, while other 4 groups (12 each) were daily fed orally with 1 mL of either 40, 500, 1000 and 1500 mg/Kg b.wt. APM dissolved in distilled water using gavages for consecutive 5 weeks. Liver samples fixed in 10% formalin were cut as 5 μm using Leica microtome and the sections were stained with both routine Heamatoxylene and Eosin (H & E) as well as Transmission electron Microscope (TEM). Histological results showed cellular changes in the hepatic tissues which were proportional with the increased doses. The hepatocytes had developed fatty droplets in the cytoplasm of almost all cells, loss of nuclei, necrosis detectable at LM level. Lymphatic nodules were also generated around the triads and the central hepatic veins as well as intracellular gaps with higher doses. The TEM results demonstrated degradation of mitochondria indicating the direct acute effects of the aspartame on hepatic tissues which all were proportional with the increased doses. It is concluded that the daily ingestion of aspartame, even at lower doses, has acute effects and is dose dependant on hepatic cells which could exert further risks onto other tissues of consumers on the long run.

Determination of Aspartame Content in Liquor by High Performance Liquid Chromatography

[Objectives]This study was conducted to establish a method for the determination of aspartame in liquor by high performance liquid chromatography.[Methods]The liquor samples having volumes fixed with ultrapure water were filtered by 0.22μm water phase,and then the content of aspartame in liquor was determined by high performance liquid chromatography using methanol(A)and ultrapure water(B)as mobile phase for isocratic elution.[Results]The results showed that a good linearity was obtained for the standard curve(R^(2)=99.98%)in the method,and its quantitative limit was 5.34 mg/kg.Its recovery was 91.26%,91.92%,and 90.55%,respectively.[Conclusions]The method has high sensitivity,high recovery and low quantitative limit,and it was a suitable method for the determination of aspartame in liquor.

前景良好的非营养型甜味剂——Aspartame

0 引言 1965年12月,美国G.D.Searle有限公司的化学工作者J.Schlatter在合成供生物分析用的四肽化合物促胃液激素时,意外发现了甜物质N—L—天冬氨酰基—L—苯丙酸氨—1—甲基酯,并命名为ASpartame。实验中,Aspartame这个中间产物溅到Schlatter的手上。因他知道这种氨基酸混合物无毒,因此就不忙于立即洗手。

Antihyperglycemic and hepatoprotective properties of miracle fruit(Synsepalum dulcificum) compared to aspartame in alloxan-induced diabetic mice

Objective: This study was undertaken to investigate the antihyperglycemic potential of miracle fruit(MF)as well as its hepatic safety as compared to aspartame in alloxan-induced diabetic mice.Methods: MF extracts were prepared and screened for their phytochemical composition using highperformance liquid chromatography(HPLC). Total phenolic, flavonoid and tannin contents and antioxidant potential were also determined. Additionally, MF was evaluated for its sensory attributes. For in vivo work, MF ethanol extract at high(MFH: 500 mg/kg body weight [BW]) and low(MFL: 250 mg/kg BW) doses as well as aspartame were injected intraperitoneally into alloxan-induced diabetic mice.Blood glucose levels were determined following acute and subchronic treatment. At the end of the study,animals were sacrificed, serum was collected for biochemical analysis and liver tissues were obtained for histopathological examination.Results: MF ethanol extract contained more flavonoids and tannins, and had higher 1,1-diphenyl-1-picrylhydrazyl radical-scavenging activity(79.61%) compared to MF aqueous extract(P < 0.05). HPLC analysis of MF ethanol extract also revealed the presence of 10 antioxidants with quercetin comprising the major polyphenol. Additionally, sensory analysis of MF showed that its intake is effective in masking undesirable sourness. Subchronic administration of MFH proved amelioration of hyperglycemia in mice as compared to aspartame. Moreover, aspartame treatment significantly elevated(P < 0.05) the level of alanine aminotransferase and had destructive effects on the liver histopathology;however, hepatic architecture was restored by low and high doses of MF.Conclusion: MF is an effective antihyperglycemic with hepatoprotective properties that can be used as a healthier alternative sweetening agent in place of aspartame for sour beverages.

Investigations on the degradation of aspartame using high-performance liquid chromatography/tandem mass spectrometry

Aspartame is a widely used sweetener, the long-term safety of which has been controversial ever since it was accepted for human consumption. It is unstable and can produce some harmful degradation products under certain storage conditions. A high-performance liquid chromatography/tandem mass spectrometry method was developed for the simultaneous analysis of aspartame and its four degradation products, including aspartic acid, phenylalanine, aspartyl-phenylalanine and 5-benzyl-3,6- dioxo-2-piperazieacetic acid in water and in diet soft drinks. Aspartame and its four degradation products were quantified by a matrix matched external standard calibration curve with excellent correlation coefficients. The limits of detection were 0.16-5.8 μg/L, which exhibited higher sensitivity than common methods. This method was rapid, sensitive, specific and capable of eliminating matrix interferences. It was also applied to the study of the degradation of aspartame at various pH and temperatures. The results indicated that aspartame was partly degraded under strong acidic or basic conditions and the extent of degradation increased with increasing temperature.

“阿斯巴甜风波”的科学问题与法律问题

1公众焦点:阿斯巴甜风波再起2023年7月14日,世界卫生组织WHO下属的国际癌症研究机构(IARC)宣布,将阿斯巴甜Aspartame列入“可能对人类致癌的物质”,列在2B类致癌物名单中。而在同一天,联合国粮农组织FAO/世界卫生组织WHO下属的世界食品添加剂联合专家委员会(JECFA)宣布:维持阿斯巴甜原风险评估结论,按照目前剂量和范围使用,阿斯巴甜不会对消费者产生健康危害。

新型高效甜味剂——Neotame

Neotame（NTM）是一种更优于Aspartame（APM）的新型高效无营养型甜味剂。NTM是Aspartame的N-取代衍生物。本文主要综述NTM的合成、性质与应用。

离子交换树脂回收L-苯丙氨酸

为降低Ａｓｐａｒｔａｍｅ生产成本，建立了１套水解二肽母液，并用离子交换树脂分离Ｌ苯丙氨酸的回收工艺。该工艺可使Ｌ苯丙氨酸回收率达７２％以上。

二肽甜味剂结构的研究进展

二肽甜味剂对N-端的结构有严格的要求,C-端却是经常可以变化的。为进一步揭示二肽甜味剂的结构,分析了一系列aspartame衍生物。研究表明,苯丙氨酸上的疏水基团X当改变其结构大小时,甜度的变化不大。而肽键对于维持甜味是必需的,用酯键取代肽键导致甜味消失,氨基上的氢键对于维持甜味来说也是必需的,当它被甲基取代时甜味也消失了。

Soft drinks consumption and nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease(NAFLD) is a common clinical condition which is associated with metabolic syndrome in 70% of cases.Inappropriate dietary fat intake,excessive intake of soft drinks,insulin resistance and increased oxidative stress combine to increase free fatty acid delivery to the liver,and increased hepatic triglyceride accumulation contributes to fatty liver.Regular soft drinks have high fructose corn syrup which contains basic sugar building blocks,fructose 55% and glucose 45%.Soft drinks are the leading source of added sugar worldwide,and have been linked to obesity,diabetes,and metabolic syndrome.The consumption of soft drinks can increase the prevalence of NAFLD independently of metabolic syndrome.During regular soft drinks consumption,fat accumulates in the liver by the primary effect of fructose which increases lipogenesis,and in the case of diet soft drinks,by the additional contribution of aspartame sweetener and caramel colorant which are rich in advanced glycation end products that potentially increase insulin resistance and inflammation.This review emphasizes some hard facts about soft drinks,reviews fructose metabolism,and explains how fructose contributes to the development of obesity,diabetes,metabolic syndrome,and NAFLD.