D-Gluconic acid, δ-lactone, reaction products with propanolamine

Basic toxicokinetics

Administrative data

Endpoint:

basic toxicokinetics, other

Type of information:

(Q)SAR

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

1. SOFTWARE: QSAR Toolbox

2. MODEL (incl. version number) : 4.0

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL: [N+H3]CCCO.OCC(O)C(O)C(O)C(O)C([O-])=O.OCCCNC(=O)C(O)C(O)C(O)C(O)CO

4. EVALUATION: see attached report

Data source

Reference

Reference Type:

other: Expert evaluation

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Objective of study:

absorption

distribution

excretion

metabolism

Principles of method if other than guideline:

- References: SIDS-gluconates and SIDS-amines
- Software tool(s) used including version: QSAR TOOLBOX

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

D-Gluconamide, N-(3-hydroxypropyl)-

Cas Number:

190445-18-2

Molecular formula:

C9H19NO7

IUPAC Name:

D-Gluconamide, N-(3-hydroxypropyl)-

Constituent 2

Reference substance name:

gluconic acid, aminopropanol salt

Molecular formula:

C9 H21 N1 O8

IUPAC Name:

gluconic acid, aminopropanol salt

Test material form:

liquid

Remarks:

50% solution in water

Details on test material:

% solids in water: 48.0 - 52.0

Results and discussion

Toxicokinetic / pharmacokinetic studies

Details on absorption:

Possible routes of uptake are via skin contact (workers and consumers) or orally (consumers). Inhalation is not a likely route of exposure considering the combination of very low vapour pressures (< 10-10 Pa) and high water solubility (1000 g/L), plus the fact that the reaction mass is produced, imported and sold as a 50% solution in water. Exposure to possible aerosols is also not very likely as these are not formed during any of the uses as a cosmetic ingredient.
In-vitro tests with skin and eye tissue show little to no irritation, indicating no significant effects on tissue cell integrity. Also, acute oral toxicity of both propanol ammonium and gluconate show a low toxic potential. This may point to a low absorption level or a high rate of metabolism before absorption occurs. The balance between D-Gluconamide, N-(3-hydroxypropyl)- and the salt is pH sensitive and subject to hydrolysis at lower (acidic) or higher (basic) pH.
Gluconic acid is a normal metabolic product of glucose metabolism and produced daily. For these reasons, conventional toxicological studies of simple gluconate salts (e.g. potassium gluconate) have not been regarded as necessary, explaining the lack of direct animal data on the compound. Orally administered gluconate is absorbed rapidly; a major part is excreted in the urine and the remainder is metabolised (Life Science Research Office, 1980).
Primary amines like aminopropanol may be absorbed through the skin, i.e. up to chain length of about six carbon atoms. The charged form in the salt will hinder absorption across biological membranes. Dermal exposures to dilute solutions will most likely not have sufficient base capacity to overwhelm the skin's natural acidity and only a few of the molecules exist as the uncharged free base. At the pH of the GI tract, only very limited, non-ionized compound would be absorbed.
The non-charged secondary amine is sensitive to hydrolysis forming 3-aminopropan-1-ol and D-gluconic acid. Oral uptake will therefore always result in hydrolysis of the main part of the 3-hydroxypropyl gluconamide. The oral endpoints of acute and repeated dose are therefore well substituted by the data for aminopropanol and/or D-gluconate.

Details on distribution in tissues:

Due to the high solubility of the different molecules and their metabolites, accumulation or bioconcentration in fat tissue or vital organs is negligible.

Details on excretion:

Both propanol ammonium salt of gluconate and D-Gluconamide, N-(3-hydroxypropyl)- and their metabolites will be mainly excreted in the urine.

Metabolite characterisation studies

Metabolites identified:

yes

Details on metabolites:

Based on QSAR Toolbox, the metabolism of Reaction mass of 3-hydroxypropan-1-aminium D-gluconate and N-(3-hydroxypropyl)-D-gluconamide, based on rat hepatocyte simulator, generates more than 10 metabolites of which most are further metabolized. The major routes of metabolism of aminopropanol involve various processes including oxidation and conjugation. Gluconate and its metabolites like arabinose and arabitol may affect insulin concentrations but at doses that do not occur at normal use of the reaction mass as a cosmetic ingredient. Although there are limited data available concerning the individual toxicity of these metabolites, there are no toxic related alerts. Where data are available these indicate a low toxicity. Based on this evaluation, the molecules forming Reaction mass of 3-hydroxypropan-1-aminium D-gluconate and N-(3-hydroxypropyl)-D-gluconamide are believed to be metabolized relatively easy involving hydrolysis, oxidation, conjugation and other enzyme-catalyzed reactions leading to detoxification and excretion.

Bioaccessibility (or Bioavailability)

Bioaccessibility (or Bioavailability) testing results:

Not evaluated.

Applicant's summary and conclusion

Conclusions:

Accumulation or bioconcentration of the test article and/or its metabolites in fat tissue or vital organs is negligible.

Executive summary:

Gluconic acid is a normal metabolic product of glucose metabolism and produced daily. For these reasons, conventional toxicological studies of simple gluconate salts (e.g. potassium gluconate) have not been regarded as necessary, explaining the lack of direct animal data on the compound. Orally administered gluconate is absorbed rapidly; a major part is excreted in the urine and the remainder is metabolised (Life Science Research Office, 1980).  

Primary amines like aminopropanol may be absorbed through the skin, i.e. up to chain length of about six carbon atoms. The charged form in the salt will hinder absorption across biological membranes. Dermal exposures to dilute solutions will most likely not have sufficient base capacity to overwhelm the skin's natural acidity and only a few of the molecules exist as the uncharged free base. At the pH of the GI tract, only very limited, non-ionized compound would be absorbed.

The non-charged secondary amine is sensitive to hydrolysis forming 3-aminopropan-1-ol and D-gluconic acid. Oral uptake will therefore always result in hydrolysis of the main part of the 3-hydroxypropyl gluconamide. The oral endpoints of acute and repeated dose are therefore well substituted by the data for aminopropanol and/or D-gluconate.

the molecules forming Reaction mass of 3-hydroxypropan-1-aminium D-gluconate and N-(3-hydroxypropyl)-D-gluconamide are believed to be metabolized relatively easy involving hydrolysis, oxidation, conjugation and other enzyme-catalyzed reactions leading to detoxification and excretion.

Due to the high solubility of the different molecules and their metabolites, accumulation or bioconcentration in fat tissue or vital organs is negligible. In fact, both propanol ammonium salt of gluconate and D-Gluconamide, N-(3-hydroxypropyl)- and their metabolites will be mainly excreted in the urine.