Advantame Chemical and Technical Assessment Prepared by Ivan Stankovic, Ph.D. and reviewed by Daniel E Folmer, Ph.D. 1. Summary Advantame was not previously evaluated by JECFA and it has been recommended for priority evaluation at the 44th Session of the Codex Committee on Food Additives (CCFA) (FAO/WHO, 2012). This Chemical and Technical Assessment document is based on data and information submitted by Ajinomoto Co., Inc., in the dossier dated December, 2012 (Ajinomoto, 2012). Advantame (ANS9801 - laboratory code name) is an N-substituted (aspartic acid portion) derivative of aspartame that is intended for use as a non-nutritive sweetener. Advantame has been demonstrated to be approximately 100 times sweeter than aspartame and approximately 37000 times sweeter than sucrose. Advantame is manufactured via a chemical synthesis. Approval for the use of advantame as a Schedule 2 food additive [permitted to Good Manufacturing Practices (GMP) in processed foods] in Australia/New Zealand has been recently issued by Food Standards Australia New Zealand (FSANZ) (FSANZ, 2011). INS No. 969 has been assigned to advantame at the 45th Session of the CCFA in 2013 (FAO/WHO, 2013) New tentative specifications were prepared at the 77th JECFA (2013) and published in FAO JECFA Monographs 14 (2013) requesting information on: • Suitability of the head space GC method (using appropriate dissolution solvent) for determination of residual solvents published in the “Combined Compendium of Food Additives Specifications, Vol. 4” and data, in a minimum of 5 batches, using the method, • An alternative/improved HPLC method for the assay of advantame and advantame-acid using a standard curve, • Additional data and analytical methods for determination of palladium and platinum, • Information on the purity and availability of the commercial reference standards used in the assay of advantame and advantame-acid 2. Description Advantame (N-[N-[3-(3-hydroxy-4-methoxyphenyl) propyl]-α-aspartyl]-L-phenylalanine 1-methyl ester, monohydrate; CAS No.: 714229-20-6) is an N-substituted (aspartic acid portion) derivative of aspartame that is similar in structure to neotame, another N-substituted aspartame. Advantame has a molecular formula of C24H30N2O7·H2O and a corresponding molecular weight of 476.52 g/mol (monohydrate). The final advantame product consists of not less than 97.0% and not more than 102.0% of C24H30N2O7 (anhydrous). Advantame appears as a white to yellow powder, with a sweet taste. At 25°C, advantame was shown to be very slightly soluble in water (0.099 g advantame/100 ml water) and sparingly soluble in ethanol (1.358 g advantame/100 ml ethanol), with solubility increasing in both solvents with heating. The structural formula for advantame is presented in Figure 1. Advantame (CTA) 2013 - Page 1 (14) Figure 1. Structural formula of advantame 3. Method of manufacture Advantame can be produced via a three-step synthetic chemical process, beginning with the production of the principal manufacturing intermediate, 3-hydroxy-4-methoxycinnamaldehyde (HMCA), from water, sodium hydroxide, and isovanillin in methanol. This is followed by selective hydrogenation of HMCA to form 3-(3-hydroxy-4-methoxyphenyl) propionaldehyde (HMPA). The final step involves N-alkylation of aspartame (L-α-aspartyl-L-phenylalanine methylester) with HMPA to form advantame. Alternatively, high-purity HMCA can be sourced externally, and thus be considered the starting material for the production process. Methanol and isopropyl acetate or ethyl acetate are used as reaction solvents and re-crystallisation solvents in the preparation of advantame. The sponsor additionally informed the Committee that isopropyl acetate is no longer used in the production of advantame. 4. Characterization 4.1 Composition The final advantame product consists of not less than 97.0% and not more than 102.0% of C24H30N2O7 (anhydrous). Specifications proposed by the sponsor include limits for N-[N-[3-(3- hydroxy-4-methoxyphenyl) propyl]-α-aspartyl]-L-phenylalanine (advantame-acid) and other related substances of not more than 1.0 and 1.5% of the product, respectively, limits for the residual solvents methanol and ethyl acetate at 500 mg/kg each, a limit for inorganic substances (residue on ignition) of 0.2%, and a limit for lead of 1 mg/kg. The sponsor had also initially proposed a limit of 2,000 mg/kg for the residual solvent isopropyl acetate, but this specification has been removed from the tentative specification based on the indication of the sponsor that isopropyl acetate is no longer used in the manufacture of advantame. 4.2 Possible impurities (including degradation products) Possible impurities of advantame include: (i) substances related to advantame; (ii) production intermediates, including HMCA, HMPA, HMPA-alcohol, di-HMPA, and isovanillin; (ii) residues of solvents (i.e., isopropyl acetate/ethyl acetate and methanol) used in the manufacturing process of advantame or their hydrolysis products (i.e., methyl acetate and 2-propanol); (iv) residues of the hydrogenation catalysts (i.e., palladium on aluminium oxide and platinum on carbon) and (v) inorganic impurities and heavy metals (lead). Substances related to advantame Several related substances of advantame have been identified in the final advantame product as manufacturing impurities. Specifically, batch analysis was conducted on 12 lots of advantame for related substances. For each sample lot, analysis was conducted using two high performance liquid chromatography (HPLC) methods. Using the first method (“old method”), co-elution of some Advantame (CTA) 2013 - Page 2 (14) related substances was identified, thus the original method was modified to increase the sensitivity and allow for better separation of the related substances. Using the modified method, a total of 27 related substances were identified in advantame. Of these, only 16 peaks were identified in amounts that were quantifiable. The majority of the related substances were found only in trace amounts in the sample lots or were not detected at all in some samples. Depending on the sample lot, values ranged from 0.55 to 1.39% for total related substance content. Of the 16 quantifiable peaks, five substances were present in the final advantame material at levels above 0.1% (up to 0.41%) and were fully characterized (i.e., principal substances related to advantame) as the following: L-α-aspartyl-L-phenylalanine methylester (Aspartame); N-[N-[3-(3-hydroxy-4-methoxyphenyl) propyl]-α-aspartyl]-L-phenylalanine (advantame- acid); N-[N-[N-[3-(3-hydroxy-4-methoxyphenyl)propyl]-α-L-aspartyl]-α-L-aspartyl]-L- phenylalanine 1-methyl ester (N-Alkyl-AAPM); N-[N-[3-(3-hydroxy-4-methoxyphenyl)pentyl]-α-L-aspartyl]-L-phenylalanine 1-methyl ester (9801-D); and N-[N-[3-(3-hydroxy-4-methoxyphenyl)heptyl]-α-L-aspartyl]-L-phenylalanine 1-methyl ester (9801-T); The structural formulas of advantame-acid, N-alkyl-AAPM, 9801-D and 9801-T are presented in Figure 2. HO2C COOH O H N N N COOH N N COOCH H H H H 3 O H CO O COOH 3 H3CO OH OH advantame-acid N-alkyl-AAPM HOOC HOOC N N COOCH3 N N COOCH H H H H 3 O O H3CO H3CO OH OH 9801-D 9801-T Figure 2. Structural formulas of advantame-acid, N-alkyl-AAPM, 9801-D and 9801-T The remaining 11 substances were identified consistently in very small quantities (below 0.1% in the final product). Substances identified in the final product at levels below 0.1% were not characterized. The peak corresponding to relative retention time (RRT) 1.24 was detected in one of the examined lots at 0.12%; however, because levels of RRT 1.24 were consistently below 0.1% in the remaining 11 lots, it too was not characterized. According to the sponsor, given the low levels at which these related substances occurred in the final product, combined with the low estimates of intake of advantame, full characterization of these related compounds was deemed unnecessary. Advantame (CTA) 2013 - Page 3 (14) Production intermediates Since advantame is produced synthetically via a series of chemical reactions, starting material (isovanillin), reaction intermediates (HMCA and HMPA), as well as reaction by-products (HMPA- alcohol, di-HMPA) could be present in the final product. Although there are no analysis data for HMCA in the final batches of advantame, the sponsor reported that the presence of this potential impurity is routinely checked during the manufacturing process. Following the selective hydrogenation reaction to form HMPA, the presence of HMCA is determined by HPLC. If HMCA is present in detectable amounts (0.02%) in the HMPA filtrate (end of step 2), the HMPA filtrate is not used in the production process for advantame. Thus, the potential for HMCA carry-over into the final product is limited during the manufacturing process. Similarly, the presence of isovanillin, HMPA, HMPA-alcohol, and di-HMPA was examined using HPLC during the development of the commercial production process. Analysis did not reveal any detectable levels of HMPA or its derivates in the production batches (detection limit of 0.02%). Hence, according to the sponsor, neither HMPA nor its derivatives are expected in the final product. Solvent residues and their reaction by-products The sponsor initially indicated that methanol and isopropyl acetate or ethyl acetate are used as reaction solvents and re crystallisation solvents in the preparation of advantame. Gas chromatographic analysis of 12 lots of advantame synthesized using methanol and isopropyl acetate was performed. While no peaks were apparent for methanol, the analysis did reveal peaks consistent with the presence of isopropyl acetate. The concentration of isopropyl acetate in the final product was determined to range from 307 to 1,907 mg/kg (mean of 573 mg/kg). Since detectable levels of isopropyl acetate were identified in the advantame samples, limits for levels of residual solvents which may be present as a result of their use in the manufacture of advantame (methanol and isopropyl acetate or ethyl acetate) were originally included in the final product specification.