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CFSAN/Office of Food Additive Safety
December 6, 2006
Edward A. Steele
President, AAC Consulting Group
7361 Calhoun Place
Rockville, MD 20855-2765
Re: GRAS Notice No. GRN 000202
Dear Mr. Steele:
The Food and Drug Administration (FDA) is responding to the notice, dated May 31, 2006, that you submitted on behalf of Zymes, LLC (Zymes) in accordance with the agency's proposed regulation, proposed 21 CFR 170.36 (62 FR 18938; April 17, 1997; Substances Generally Recognized as Safe (GRAS)). FDA received this notice on June 1, 2006, filed it on June 5, 2006, and designated it as GRN No. 000202.
The subject of the notice is polyoxyethanyl-alpha-tocopheryl sebacate (PTS). The notice informs FDA of the view of Zymes that PTS is GRAS, through scientific procedures, as a solubilizer for the dietary ingredient coenzyme Q10 (CoQ10) in dietary supplements.
As part of its notice, Zymes includes the report of a panel of individuals (Zymes' GRAS panel) who evaluated the data and information that are the basis for Zymes' GRAS determination. Zymes considers the members of its GRAS panel to be qualified by scientific training and experience to evaluate the safety of substances added to food. Zymes' GRAS panel discusses the identity, specifications, method of manufacture, and proposed estimated dietary intake of PTS. Zymes' GRAS panel also discusses published safety studies on PTS, on polyethylene glycol (PEG), on other PEGylated alpha-tocopherol (also referred to as Vitamin E) carriers,(1) and on alpha-tocopherol. Zymes' GRAS panel also discusses several published studies on sebacic acid. Based on this review Zymes' GRAS panel concluded that PTS is GRAS for use as a solubilizer for the dietary ingredient CoQ10 in dietary supplements.
Zymes describes PTS. Below its melting point of 25°C, PTS is a yellow-orange wax. Above 25°C, PTS is a yellow-orange viscous fluid that dissolves in water, alcohols, dichloromethane and tetrahydrofuran, but not in hexane. PTS is hygroscopic and stable at room temperature in aqueous solution.
Zymes describes the method of manufacture and provides specifications for PTS. PTS is manufactured by two consecutive esterification reactions under anhydrous conditions in ethylacetate with added triethylamine. Alpha-tocopherol is first linked to sebacoyl dichloride by esterification at its hydroxy terminus. The resultant alpha-tocopheryl mono-ester of sebacoyl chloride is subsequently esterified with PEG (molecular weight (mol. wt.) 600) (PEG600) to form PTS. PTS is subsequently purified using acetonitrile and hexane to remove the major impurity, di-alpha-tocopheryl-sebacate, which is formed as a by-product of sebacoyl chloride diester formation with alpha-tocopherol. Zymes provides specifications for residual solvents and for contaminants, including lead and heavy metals for PTS.
Zymes estimates the consumer intake of PTS. Zymes estimates that the intake of PTS would be limited to 1200 mg/p/day or 20 milligram per kilogram of bodyweight per day (mg/kg bw/day) from the intended uses.
Zymes notes that the expected metabolism of PTS is to its component substances, alpha-tocopherol, sebacate (sebacic acid) and PEG600. Given this expected metabolic fate, Zymes considered safety studies on the individual components of PTS and structurally similar compounds.
Zymes notes that given the common natural food presence of alpha-tocopherol as an essential nutrient and its approval as a multipurpose direct food additive, the safety of this component of PTS is considered well established at moderate intake levels. Zymes states that with the intended use and intake of 420 mg/p/day of alpha-tocopherol in PTS, and 300 mg alpha-tocopherol/day from other sources, the maximum estimated consumer intake of 720 mg/p/day of alpha-tocopherol is below the tolerable upper intake level which is 1000 mg/p/day as set by the National Academy of Science's Institute of Medicine.
Zymes describes several published safety studies that show that sebacic acid does not raise any notable toxicological concerns. In these studies, there was a lack of mutagenicity as determined by microbial assays; there was no toxicity in acute oral studies up to 6000 mg/kg bw/day; and, toxicological effects in chronic toxicity and teratological evaluations in rodents and rabbits were not observed up to 1000 mg/kg bw/day of sebacic acid. The likely consumer intake of sebacic acid in PTS would be approximately 4 mg/kg bw/day.
Zymes describes published studies that show that PEGs in the molecular weight range of 400-1500 are practically non-toxic in acute oral studies (~4 g PEG600/kg bw/day) across animal species. Based on these studies, Zymes concludes that PEG600 in PTS should not pose any notable toxicological concerns. Zymes considers the likely consumer intake of PEG600 from PTS would be approximately 9 mg/kg bw/day, which is below the Joint Expert Committee on Food Additives' acceptable daily intake of 10 mg/kg bw/day for PEGs.
Zymes describes a published safety assessment of d-alpha-tocopherol polyethylene glycol (mol. wt. 1000) succinate (TPGS), a PEGylated molecule that is similar to PTS. Zymes considers TPGS and PTS to be sufficiently structurally similar to draw meaningful direct comparisons regarding the safety of PTS. In Zymes' assessment, TPGS did not exhibit any adverse effects in reproductive, developmental, or subchronic toxicity when given orally to rats at doses up to approximately 1000 mg/kg bw/day. Based on results of this published study, Zymes considers the no-observed-adverse effect level of TPGS to be higher than 1000 mg/kg bw/day.
Zymes describes published and unpublished screening studies conducted on a series of PEGylated lipophilic compounds to assess their suitability for use as carrier molecules. One of the compounds synthesized and tested was PTS. These studies show that:
- PTS does not produce cytotoxicity in a human immortalized cell line as measured by trypan blue exclusion and alteration of cellular or nuclear morphology.
- PTS does not induce acute cardiotoxicity in excised rat hearts infused with PTS. Parameters measured were left ventricular pressure, heart rate, end diastolic pressure and developed pressure.
- Repeat dose toxicity testing in rodents of up to 40 mg/kg bw/day of dietary PTS and up to 40 mg/kg bw/day of dietary PTS-CoQ10 for 30 days does not produce gross pathology or histopathological effects in the tissues examined.
Based on the information provided by the Zymes, as well as other information available to FDA, the agency has no questions at this time regarding Zymes' conclusion that PTS is GRAS under the intended conditions of use. The agency has not, however, made its own determination regarding the GRAS status of the subject use of PTS. As always, it is the continuing responsibility of Zymes to ensure that food ingredients that the firm markets are safe, and are otherwise in compliance with all applicable legal and regulatory requirements.
In accordance with proposed 21 CFR 170.36(f), a copy of the text of this letter responding to GRN 000202, as well as a copy of the information in this notice that conforms to the information in the proposed GRAS exemption claim (21 CFR 170.36(c) (1)), is available for public review and copying on the homepage of the Office of Food Additive Safety (on the Internet at http://www.cfsan.fda.gov/~lrd/foodadd.html).
Laura M. Tarantino, Ph.D.
Office of Food Additive Safety
Center for Food Safety and Applied Nutrition
(1) PEGylated alpha-tocopherol carriers have polyethylene glycol molecules attached.