O,O'-dioctadecylpentaerythritol bis(phosphite)

Basic toxicokinetics

Administrative data

Endpoint:

basic toxicokinetics in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

April 2002 to November 2002

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: A non-GLP study performed to sound scientific principles with a sufficient level of detail to assess the quality of the submitted data.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2003

Report date:

2003

Materials and methods

Objective of study:

metabolism

Test guideline

Qualifier:

according to guideline

Guideline:

other: Note for Guidance of Food Contact Materials, SANCO D3/LR D(2002), Annex 1

Deviations:

no

Principles of method if other than guideline:

The hydrolysis of the test material, and it’s by product (oxidised form of the test material) was investigated in simulated gastric juice and intestinal fluid. The stimulants were analysed by either GC/MS or HPLC/MS after incubation to detect either the parent substance or two predicted hydrolysis products. The results of the analyses were confirmed by analysing the content of the parent substance for the presence of the hydrolysis products.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

O,O'-dioctadecylpentaerythritol bis(phosphite)

EC Number:

223-276-6

EC Name:

O,O'-dioctadecylpentaerythritol bis(phosphite)

Cas Number:

3806-34-6

Molecular formula:

C41H82O6P2

IUPAC Name:

3,9-bis(octadecyloxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane

Test material form:

not specified

Details on test material:

PARENT
- Name of test material (as cited in study report): Distearyl pentaerythritol diphosphite
- Storage condition of test material: room temperature

OXIDISED FORM OF PARENT
- Name of test material (as cited in study report): Distearyl pentaerythritol diphosphate
- Storage condition of test material: room temperature

Radiolabelling:

no

Administration / exposure

Details on exposure:

Samples of the parent substance and the oxidised by-product of the parent substance were incubated at 37°C in either gastric juice simulant or intestinal fluid simulant.

Duration and frequency of treatment / exposure:

4 hours

Results and discussion

Main ADME results

Main ADME results 1

Type:

metabolism

Results:

The diphosphite is oxidised to diphosphate to some extent under gastric conditions

Main ADME results 2

Type:

metabolism

Results:

The oxidised substance (phosphate) is stable in gastric juices and intestinal fluid.

Any other information on results incl. tables

 Table 1: Hydrolysis of parent after incubation in gastric juice simulant – Analysis of 1-octadecanol

Incubation Conditions	Sample No. (hours)	1-Octadecanol measured in simulant (µg/mL)
Before incubation	1 (0 h)	54.55
	2 (0 h)	56.5
	3 (0 h)	55.23
	Mean ± S.D.	55.43 ± 0.99
1 hour at 37°C	1 (1 h)	60.63
	2 (1 h)	57.17
	3 (1 h)	66.41
	Mean ± S.D.	61.40 ± 4.97
2 hours at 37°C	1 (2 h)	58.54
	2 (2 h)	55.91
	3 (2 h)	52.29
	Mean ± S.D.	55.58 ± 3.14
4 hours at 37°C	1 (4 h)	63.41
	2 (4 h)	61.47
	3 (4 h)	62.47
	Mean ± S.D.	62.45 ± 0.97

Nominal concentration of parent in simulant: 116.6 µg/mL

Nominal concentration of 1-octadecanol in parent (confirmed by analysis): 38.8 µg/mL

Nominal concentration of 1-octadecanol assuming complete hydrolysis of parent: 56 to 61 µg/mL (84 to 95 µg/mL when including tristearylphosphate)

 

Table 2: Hydrolysis of parent after incubation in gastric juice simulant – Analysis of pentaerythritol

Incubation Conditions	Sample No. (hours)	Pentaerythritol measured in simulant (µg/mL)
Before incubation	1 (0 h)	0.15
	2 (0 h)	0.15
	3 (0 h)	< 0.1
	Mean ± S.D.	0.1 ± 0.1
1 hour at 37°C	1 (1 h)	0.32
	2 (1 h)	0.22
	3 (1 h)	0.21
	Mean ± S.D.	0.25 ± 0.06
2 hours at 37°C	1 (2 h)	0.22
	2 (2 h)	0.10
	3 (2 h)	0.12
	Mean ± S.D.	0.15 ± 0.06
4 hours at 37°C	1 (4 h)	0.20
	2 (4 h)	0.21
	3 (4 h)	0.19
	Mean ± S.D.	0.20 ± 0.01

Nominal concentration of parent in simulant: 105.1 µg/mL

Nominal concentration of pentaerythritol assuming complete hydrolysis of parent: 13 to 14 µg/mL

 

Table 3: Hydrolysis of parent after incubation in gastric juice simulant – Analysis of parent

Incubation Conditions	Sample No. (hours)	Parent substance measured in simulant		Oxidised parent measured in stimulant (µg/mL)
		(µg/mL)	(% of nominal)
Before incubation	1 (0 h)	< 1	< 20	3.8
	2 (0 h)	< 1	< 20	2.7
	3 (0 h)	< 1	< 20	1.7
	Total mean:	< 1	< 20
1 hour at 37°C	1 (1 h)	< 1	< 20	< 0.5
	2 (1 h)	< 1	< 20	< 0.5
	3 (1 h)	< 1	< 20	< 0.5
	Total mean:	< 1	< 20
2 hours at 37°C	1 (2 h)	< 1	< 20	< 0.5
	2 (2 h)	< 1	< 20	< 0.5
	3 (2 h)	< 1	< 20	< 0.5
	Total mean:	< 1	< 20
4 hours at 37°C	1 (4 h)	< 1	< 20	< 0.5
	2 (4 h)	< 1	< 20	< 0.5
	3 (4 h)	< 1	< 20	< 0.5
	Total mean:	< 1	< 20

 

Nominal concentration of parent in simulant: 5.30 µg/mL

Nominal concentration in analytical sample after preparation: 26.5 µg/mL

 

Table 4: Hydrolysis of oxidised parent after incubation in gastric juice simulant – Analysis of oxidised parent

Incubation Conditions	Sample No. (hours)	Parent substance measured in simulant
		(µg/mL)	(% of nominal)
Before incubation	1 (0 h)	5.87	105
	2 (0 h)	6.11	109
	3 (0 h)	6.02	107
	Total mean:	6.00	107 ± 2 (n = 3)
1 hour at 37°C	1 (1 h)	5.77	103
	2 (1 h)	5.87	105
	3 (1 h)	5.56	99
	Total mean:	5.73	102 ± 3 (n = 3)
2 hours at 37°C	1 (2 h)	6.20	111
	2 (2 h)	6.02	107
	3 (2 h)	5.38	96
	Total mean:	5.87	105 ± 8 (n = 3)
4 hours at 37°C	1 (4 h)	5.85	104
	2 (4 h)	5.16	92
	3 (4 h)	6.04	108
	Total mean:	5.68	101 ± 8 (n = 3)

Nominal concentration of oxidised parent in simulant: 5.61 µg/mL

Nominal concentration in analytical sample after preparation: 28.1 µg/mL

 

Table 5: Hydrolysis of oxidised parent after incubation in intestinal fluid simulant – Analysis of oxidised parent

Incubation Conditions	Sample No. (hours)	Parent substance measured in simulant
		(µg/mL)	(% of nominal)
Before incubation	1 (0 h)	6.83	68
	2 (0 h)	7.20	72
	3 (0 h)	7.99	80
	Total mean:	7.36	73 ± 6 (n = 3)
1 hour at 37°C	1 (1 h)	6.68	66
	2 (1 h)	6.53	65
	3 (1 h)	7.17	71
	Total mean:	6.79	68 ± 3 (n = 3)
2 hours at 37°C	1 (2 h)	8.09	81
	2 (2 h)	8.65	86
	3 (2 h)	7.84	78
	Total mean:	8.19	82 ± 4 (n = 3)
4 hours at 37°C	1 (4 h)	8.14	81
	2 (4 h)	7.66	75
	3 (4 h)	8.16	81
	Total mean:	7.99	79 ± 3 (n = 3)

Nominal concentration of oxidised parent in simulant: 10.05 µg/mL

Nominal concentration in analytical sample after preparation: 10.05 µg/mL

MS spectra

- MS spectrum of the parent (1^st batch): the main signals were from the monoxidised form and tristearylphosphate, which is the oxidised form of tristearylphosphite. Distearyl pentaerythritol diphosphate was also present.

- MS spectrum of the parent (2^nd batch): a small signal of distearyl pentaerythritol diphosphite was present; the main signal was from the monooxidised form. Tristearylphosphite and distearyl pentaerythritol diphosphate were also present.

- MS spectrum of the oxidised parent (1^st batch): the main signal was from the monooxidised form. Distearyl pentaerythritol dphosphite, distearyl pentaerythritol diphosphate and tristearylphosphate were also present.

- MS spectrum of the oxidised parent (2^nd batch): the main signal was from distearyl pentaerythritol diphosphate. Tristearylphosphate was also present.

It was evident that in the parent substance, the active substance, distearyl pentaerythritol diphosphite is present at low levels, the main compound in the solutions of the parent substance was the monooxidised form of the diphosphite. This indicated that the diphosphite is easily oxidised to the monophosphate. The monophosphate is more stable towards oxidation. It was not determined whether this occurred in the solid product, or if this resulted from handling the parent in solution.

GC and HPLC/MS Analysis

- Parent in gastric juice simulant- analysis of 1-octadecanol: the hydrolysis determination of the parent in gastric juice was based on 1-octadecanol, a possible hydrolytical degradation product. GC analysis showed a measured concentration of 1-octadecanol of 55-62 µg/mL. This shows that 1-octadecanol was produced during incubation. However, it is not clear whether this can be attributed to hydrolysis of the parent or of tristearylphosphite. The high content of 1-octadecanol in the test material indicated that hydrolysis to 1-octadecanol had already occurred in the test material to a considerable extent. Therefore, a new batch of test material was obtained for analysis. The analytical method under the conditions of this assay yielded a mean recovery of 104 ± 1 % for 1-octadecanol confirming the accuracy of the method. The linearity was demonstrated to be in the calibration range with an R² of 0.999.

- Parent in gastric juice simulant- analysis of pentaerythritol: the hydrolysis of the parent in gastric juice stimulant was made based on analysis of pentaerythritol, a possible hydrolytical degradation product of the test material. HPLC/MS analysis showed the pentaerythritol eluted closely to an interfering peak, which made it difficult to integrate the pentaerythritol peak itself. The so-obtained concentrations of pentaerythritol were found to be in the range of 0.1 to 0.3 µg/mL. From the results it can be concluded that there is no hydrolysis of the parent to pentaerythritol in gastric juice stimulant. The analytical method under the conditions of this assay yielded a mean recovery of 92 ± 9 % for pentaerythritol confirming the accuracy of the method. The linearity was demonstrated to be in the calibration range with an R² of 0.99.

- Parent in gastric juice simulant- analysis of parent: HPLC/MS analysis could not detect distearyl pentaerythritol diphosphite in samples in contact with gastric juice. Furthermore it was found that the calibration solutions were not stable with respect to diphosphite: in calibration solutions standing for approximately 10 hours on the autosampler, no signal of diphosphite could be detected. As additional information, the diphosphate was also evaluated in the samples. This compound could only be detected in the non-incubated samples. In calibration solutions standing for approximately 10 hours on the autosampler, the signal of diphosphate was around twice the previous value. Findings show that diphosphite is rapidly oxidised to diphosphate. In gastric juice samples the diphosphite is also not stable. The linearity of the method was demonstrated to be in the calibration range with an R² of 0.999, as the substance could not be detected, the validity of the method could not be confirmed.

- The oxidised form of the parent in gastric juice simulant- analysis of the oxidised parent: the hydrolysis of the test material in gastric juice stimulant was based on distearyl pentaerythritol diphosphate. HPLC/MS analysis found mean recoveries of the oxidised parent to be in the range of 102 – 105% after 2 hours and 101 % after 4 hours incubation. This showed the stability of the oxidised form of the parent during incubation. The analytical method under the conditions of this assay was demonstrated to have a mean recovery of 107 ± 2% for the oxidised parent confirming the accuracy of the method. The linearity was demonstrated to be in the calibration range with an R² of 0.994.

- The oxidised parent in intestinal fluid simulant - analysis of the oxidised parent: mean recoveries of the oxidised parent were found to be in the range of 68 % after 1 hour, 82% after 2 hours and 79 % after 4 hours incubation. There were losses in the samples, however, the non-incubated samples gave even lower recoveries (73 %). Thus losses of the oxidised form were not due to hydrolysis but due to a deficit of the analytical method. Since the recoveries of the non incubated samples were nearly comparable to the incubated samples, it can be concluded that the oxidised parent is hydrolytically stable in intestinal fluid. The analytical method under the conditions of this assay yielded a mean recovery of 73 ± 6 % it is anticipated that the loss of compounds was the result of incomplete extraction, however for the purpose of the test, the accuracy and precision of the method was deemed acceptable. The linearity was demonstrated to be in the calibration range with an R² of 0.99.

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information): bioaccumulation potential cannot be judged based on study results
The hydrolysis determination of the by product (the oxidised form of the test material (parent)) in gastric juice simulant and intestinal fluid simulant, showed the stability of the oxidised parent substance during incubation. The hydrolysis determination of the parent in gastric juice simulant showed that the compound could not be detected, thus, diphosphite is not stable in gastric juice. It is not, or only to a low extent, oxidised to diphosphate. In calibration solutions in THF/water, the diphosphite is rapidly oxidised to the diphosphate. Hydrolysis determination of the parent was also based on two possible hydrolytical degradation products (1-octadecanol and pentaerythritol), however, it was found that 1-octadecanol is contained in the test material to a considerable extent and pentaerythritol was not found to be a hydrolysis product. In conclusion, a complete hydrolysis of test material (parent) and its oxidised by-product in gastric juice and intestinal fluid simulant into 1-octadecanol, pentaerythritol and phosphoric acid, could not be shown.

Executive summary:

Hydrolysis of the test parent and the by-product (the oxidised form of the parent), was investigated in simulated gastric fluid and intestinal fluid. Samples were incubated at 37ºC and directly analysed after 1, 2 and 4 hours by GC or HPLC/MS. Under the conditions of the study, the hydrolysis determination of the oxidised parent in gastric juice simulant, and intestinal fluid simulant, showed the stability of the oxidised parent during incubation. The hydrolysis determination of parent in gastric juice simulant showed that the compound could not be detected, thus, diphosphite is not stable in gastric juice. The parent is not, or only to a low extent, oxidised to diphosphate. In calibration solutions in THF/water, the diphosphite is rapidly oxidised to the diphosphate. Hydrolysis determination of the parent was also based on some possible hydrolytical degradation products (1-octadecanol and pentaerythritol), however, it was found that 1-octadecanol is contained in the test material to a considerable extent and pentaerythritol was not found to be a hydrolysis product. In conclusion, a complete hydrolysis of test material (parent) and its oxidised by-product in gastric juice and intestinal fluid simulant into 1-octadecanol, pentaerythritol and phosphoric acid, could not be shown.