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Toxicological information

Basic toxicokinetics

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Administrative data

Endpoint:
basic toxicokinetics in vivo
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Study period:
Prior to 1998
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: No information available whether study followed GLP and/or test guidelines, but sufficient data is available for interpretation of results.

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1998

Materials and methods

Objective of study:
toxicokinetics
Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Multiple studies conducted on labeled polyglycerol and polyglycerol polyricinoleate to determine absorption, excretion and metabolism in the rat.
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Test material form:
not specified
Details on test material:
[1-14C]glycerol (200 μCi) was placed in a 10 ml B14 test-tube with 2.0 g glycerol. 100 μl 10% (w/v) sodium hydroxide solution was added and the test-tube was fitted with a distillation head. A fine nitrogen leak was placed through the distillation head reaching the bottom of the tube. Nitrogen was bubbled through at approximately 20 ml/min affording a vigorous stirring of the glycerol. The nitrogen flowing out of the flask passed through a water trap to ensure that a nitrogen atmosphere was maintained in the reaction flask. The glycerol was then heated on a Woods metal-bath for 7 hr at 240°C. The reaction was sampled at hourly intervals and examined by thin-layer chromatography (TLC). The excess glycerol was not removed by vacuum distillation.

In the small-scale preparation of [14C]polyglycerol it was found to be difficult to reproduce exactly the composition of commercial polyglycerol. The preparations were either under-reacted, in which case there was an excess of glycerol, or over-reacted, in which case the presence of higher polymers was apparent. Several samples of polyglycerol were obtained which were suitable for use in the metabolic studies. These ranged in specific activity from 20 to 105 μCi/g and also had a free glycerol composition from 10 to 30%. A note of the polyglycerol used was made in each experiment.

A sample of [14C]polyglycerol was fractionated on Sephadex G10. An aqueous solution (1.0 ml) containing 500 mg [14C]polyglycerol (60 μCi) was placed on a 90×2 cm Sephadex G-10 column and diluted with water containing 1% n-butanol. Fractions 9–20 contained the 14C. These fractions were pooled (9–11, 12–14, 15–17, 18–20) to give four overall fractions rich in lower or higher polyglycerols.

Synthesis of ([14C]polyglycerol)PGPR
Polyricinoleic acid (9.5 g, supplied by Food Industries Limited, Bromborough, UK) was placed in a 25 ml, long double-necked pear-shaped flask. To this, 855 mg (82 μCi) [14C] polyglycerol was added. The flask was fitted with a fine nitrogen leak and the flask was evacuated to 20 mm Hg pressure. The nitrogen leak provided a good stirring action and the pressure was maintained at 20 mm pressure. The mixture was heated on a Woods metal-bath for 7.5 hr at 210°C. After this time, 500 mg were removed and titrated against 0.1 n sodium hydroxide to determine the acid value. The PGPR was dissolved in ethyl acetate and washed with water to remove unreacted polyglycerol. The ethyl acetate was removed in a rotary evaporator and the PGPR was dried in vacuo. The ([14C]polyglycerol) PGPR had a specific activity of 7.4 μCi/g and an acid value of 1.8.

Synthesis of ([14C]stearyl)PGPR
Castor bean oil fatty acids (10.0 g) and 500 μCi (11.6 mg) [1-14C]stearic acid were placed in a 25-ml pear-shaped flask. The flask had a B14 neck 5 cm long, and a Bl0 side arm 12 cm long which acted as air condensers. A fine nitrogen leak was fitted and the flask evacuated to 20 mm Hg pressure. The nitrogen leak provided a vigorous stirring action. The flask was heated on a Woods metal-bath for 10 hr at 205–210°C. After this heating period a sample of the reactants were withdrawn, weighed and titrated against 0.1n sodium hydroxide solution to determine the acid value. Heating of the flask under the above conditions continued in half-hourly periods until the acid value was 35 or less. The product had a specific activity of 52.6 μCi/g and an acid value of 34. A sample was methylated with diazomethane and TLCs were run. Reverse isotope dilution analysis showed that 18.8% of the 14C activity in the polymer was as free stearic acid.

Synthesis of [ 3H]PGPR
[12-3H]ricinoleic acid (500 μCi synthesized at Unilever Research Laboratories Vlaardingen, The Netherlands) and 1.8 g castor bean oil fatty acids were mixed in a two-necked flask which was fitted with a fine nitrogen leak. The mixture was heated for 16 hr at 205°C and 20 mm Hg pressure. The polymerization was checked by TLC of the products since insufficient material was available for an acid value determination. l80 mg commercial polyglycerol (Food Industries Ltd) was added to the tritiated polyricinoleic acid sample. The mixture was heated for 12 hr at 205°C at 20 mm pressure using a fine nitrogen leak for stirring. The final product was checked chromatographically for free polyricinoleic acid. The ([12-3H]ricinoleic) PGPR had a specific activity of 239 μCi/g.

This preparation was repeated with [9,10-3H]ricinoleic acid (synthesized at Unilever Research Laboratories Vlaardingen, The Netherlands). The resulting [9,10-3H](ricinoleic)PGPR had a specific activity of 256 μCi/g.

The choice of labelled ricinoleic acid was based only on availability of labelled material at the time of synthesis.

Acid value determinations
The acid value of a fat is the number of mg KOH required to neutralize 1.0 g fat. Weighed samples of material were titrated against 0.1 n NaOH to an endpoint of pH 7.0. The acid value was then determined by converting the NaOH result into that which would have been obtained if KOH had been used directly.






Radiolabelling:
yes
Remarks:
[1-14C]glycerol used to produce polyglycerol

Test animals

Species:
rat
Strain:
Wistar
Sex:
male
Details on test animals and environmental conditions:
Male rats (Colworth Wistar, 177–300 g) were used throughout these experiments. Body weights, group sizes and dosage schedules are detailed in Table 2. Unless otherwise specified, animals were allowed free access to water and Spital diet at all times. The animals were weighed prior to dosing.

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
water
Details on exposure:
See Table 2
Doses / concentrations
Remarks:
Doses / Concentrations:
See Table 2
No. of animals per sex per dose:
See Table 2. Typically 6 or 12 but occasionally fewer (1-3).
Control animals:
not specified
Positive control:
No data
Details on study design:
The animals were weighed prior to dosing. Animals were dosed by gavage with up to 2.0-ml samples of the PGPR preparations from an all-glass syringe connected to a number 1 polythene cannula. Immediately after dosing the animals were placed in metabolism cages and sealed in for up to 4 days after dosing. A flow rate of 3 litres air/min was maintained through the cages and CO2 absorbing traps. The expired CO2 was monitored for 14C activity at hourly intervals for 12 hr and then at 24, 48, 72 and 96 hr, and the urine and faeces collected at 24-hr intervals for 14C analysis. In one experiment, after 48 hr the animals were killed by asphyxiation with CO2 and samples of epididymal fat and liver were taken for 14C analysis.

After dosing rats with [3H]PGPR they were placed in metabolism cages and expired air passed through scrubbing towers containing distilled water. The 3H content of this water was monitored every hour. Urine, faeces and tissue samples were all prepared for analysis in the same way as for the 14C assays.

The carcasses of some animals were dissected and the alimentary canal removed. Samples of liver, terminal heart blood, epididymal fat and brain were taken. The intestinal contents were taken by washing with distilled water and rinsing the tissues with methanol. The stomach contents were taken separately, as were the upper small intestine (USI) middle small intestine (MSI) and lower small intestine (LSI) and the caecum and rectum. The division of the small intestine was made by dividing the whole small intestine into three equal lengths. Each sample of washings was acidified with 1.0 ml concentrated HCl to approximately pH 3 and extracted with 3×50 ml chloroform. The chloroform extracts were pooled and dried over anhydrous sodium sulfate and aliquots were pipetted into counting vials. The chloroform was evaporated and the sample counted directly in 10 ml liquid scintillator. The washed tissues were taken and analysed for 3H activity.

Details on dosing and sampling:
Simple aqueous solutions of glycerol and polyglycerol samples were used. PGPR samples were prepared as aqueous emulsions, by homogenizing PGPR in distilled water with a 0.5-in. diameter homogenizer (Silverson Machines Ltd, Chesham, UK) or dispersed on sieved (50 mesh) powdered diet which was slurried with water.

Results and discussion

Toxicokinetic / pharmacokinetic studies

Details on absorption:
The excretion in urine, faeces and expired air of 14C or 3H following dosing with 14C or 3H labelled PGPR or PGPR components is detailed in Table 3.

Details on distribution in tissues:
See Tables below.
Details on excretion:
The excretion in urine, faeces and expired air of 14C or 3H following dosing with 14C or 3H labelled PGPR or PGPR components is detailed in Table 3.

Metabolite characterisation studies

Metabolites identified:
yes
Details on metabolites:
14C-labelled glycerol is extensively metabolized to CO2. 14 C-labelled polyglycerol is not metabolized (di-and triglycerol is excreted unchanged in urine while tetraglycerol and higher MW glycerols are excreted unchanged in feces).

Polyglycerol Polyricinoleate is metabolized to polyglycerol and polyricinoleate or ricinoleic acid.

Any other information on results incl. tables

Table 3.Percentage excretion of14C or3H in urine, faeces and expired air of ratsaintubated with14C- or3H-labelled PGPR and14C-labelled components of PGPR

Percentage of administered14C or3H excreted
Urine Faeces Expired air Total
Days Experimentno. 1 2 3 4 1+2 1 2 3 4 1+2 1 2 1+2 1+2
Test material and presentation 14C Experiments
[1-14C]glycerol 1/ 11.7 0.4 12.1 3.0 0.7 3.7 67.0 1.5 68.5 84.3
50% aqueous solution
[14C]polyglycerol
50% aqueous solution 2/ 28.8 1.7 30.5 42.5 9.5 52.0 5.3 0.2 5.5 88.0
10% aqueous solution 3/ 23.3 1.2 (<0.1)b (<0.1)+ 24.5f 46.5 14.4 (1.3)b (<0.1)+ 62.22 6.0 <0.1 6.0 92.7c
3% dietary slurry 4/ 29.0 1.5 30.5 44.7 4.3 49.0 8.0 8.0 87.5
([14C]polyglycerol)PGPR
50% aqueous emulsion 6/ 19.4 1.0 (0.2)b (<0.1)+ 20.6f 35.8 9.7 (0.5)b (<0.1)+ 46.02 2.6 0.2 2.8 69.4c
3% dietary slurry 7/ 23.0 8.0 31.0 38.0 16.3 54.3 8.3 8.3 93.6
Stearic acid-1-14C
(dietary slurry) 8/ 1.1 0.4 1.5 3.5 1.2 4.7 31.8 6.9 38.7 44.9
[1-14C-stearic]PGPR
3% dietary slurry 9/ 1.4 0.3 1.7 12.7 2.1 14.8 21.6 3.1 24.7 41.2
(fed overnight)
      3H Experiments                                       
  [12-3H-ricinoleic]PGPR  10/  10.7  -  -  -  10.7  4.8  -  -  -  4.8  4.4  -  4.4  19.9
  3% dietary slurry                              
  [9.10-3H-ricinoleic]PGPR 11/   11.4  -  -  -  11.4  11.6  +  -  -  11.6  4.4  -  4.4  27.4
  3% dietary slurry                              

Groups of 3–15 rats were used; seeTable 2.

bValues for days 3 and 4 are also given.

cTotals include values for days 3 and 4.

Turnover of [1-14C]glycerol, [14C]polyglycerol and ([14C]polyglycerol)PGPR

With [1-14C]glycerol, over 84% of the dose was excreted within 48 hr, mainly as expired14CO2. With [14C]polyglycerol, 87.5–92.7% of the dose was excreted within 48 hr, mainly in the faeces, to a lesser extent in the urine and only to a small extent as expired14CO2. Only minor differences were observed in the excretory pattern of the three different dose presentations of [14C]polyglycerol, samples of which contained 9–14% free [1-14C]glycerol.

Table 4shows that following dosing with Sephadex fractions of [14C]polyglycerol, the lower glycerols were preferentially excreted in the urine, while the higher glycerols were preferentially excreted in the faeces. About 85% of the dose was recovered for each fraction in agreement with the percentage excretion of unfractionated [14C]polyglycerol (Table 3). No14CO2was expired by the animals dosed with fractions which were free of [1-14C]glycerol

Table 4.Percentage excretion of14C in urine, faeces and expired air of rats up to 2 days after an oral doseaof Sephadex-fractionated [14C] polyglycerol (experiment 5)

Percentage of administered14C excreted
Composition of Sephadex-fractionated[14C]polyglycerol Day Urine Faeces Expiredair Total after 2 days
Starting material: mono (27.4%), di (33.2%), tri (18.1%),
tetra (9.2%), penta (4.5%), hexa (2.2%), hepta (5.5%)
Fraction 1b: Mono (25.2%), di (63.7%), tri (8.2%) 1 36.6 31.4
2 2.3 4.5 5.8
1+2 38.9 35.9 5.8 85.4
Fraction 2b: Di (36.6%), tri (51.1%), tetra (9.3%) 1 33.9 48.0 0.0
2 1.4 2.1 0.0
1+2 35.3 50.1 0.0 85.4
Fraction 3b: Di (12.1%), tri (53.2%), tetra (28.9%), penta (5.6%) 1 23.4 49.9 0.0
2 2.3 7.3 0.0
1+2 25.7 57.2 0.0 82.9
Fraction 4b: Tri (9.3%), tetra (32.5%), penta (33.3%), hexa (24.9%) 1 12.5 69.0 0.0
2 0.7 3.2 0.0
1+2 13.2 72.2 0.0 85.4

a Oral doses of 1ml of 10% (w/v) aqueous solutions of fractions 1, 2, 3 and 4 were given to groups of 2, 1, 2 and 1 rats (250g body weight) respectively.

bValues for fractions 1 and 3 are the averages for two rats and for fractions 2 and 4 for one rat only.

The excretion of [14C]polyglycerol]PGPR, dosed as a 3% dietary slurry, followed the same pattern as that of [14C]polyglycerol but when dosed as a 50% aqueous emulsion the recovery of [14C]PGPR was less efficient, even though excretion was followed for 4 days after dosing (Table 3).

Identification of metabolites in excreta of rats dosed with ([14C]polyglycerol)PGPR and its components

TLC analysis of urine of rats dosed with [14C]polyglycerol (10% aqueous solution) showed that14C was mainly present as cyclic glycerols, diglycerol and triglycerol with very small amounts of higher glycerols. In contrast, faecal14C was accounted for mainly by higher glycerols and only to a smaller extent by di- and triglycerols.

Turnover of [1-14C]stearic acid and ([14C]stearyl) PGPR

[1-14C]stearic acid was metabolized by the rat and 51.3% of the dose was recovered, mainly as expired14CO2within 48 hr of dosing. Animals fed ([14C]stearyl)PGPR as a dietary slurry gave similar results to [14C] stearic acid. A total recovery of 57.7% of the dose was made in 48 hr. The increase in recovery was mainly due to a higher faecal14C recovery. Urinary and expired14C levels were similar (Table 3).

Chromatography of faeces of rats given ([14C]stearyl)PGPR as a 3% dietary slurry showed that 97% of faecal14C was free fatty acids or polyricinoleic acid and reverse isotope dilution analysis showed 44% to be free stearic acid.

Chromatographic analysis of the epididymal fat of rats dosed with ([14C]stearyl)PGPR (3% dietary slurry) revealed the presence of saturated fatty acids (44% of fat14C) monoenoic fatty acids (14%) and polyenoic fatty acids (40%).

Table 5.Uptake of14C into liver and epididymal fat 2 or 4 days after dosing with [14C]PGPR to rats

Test material and dose 14C activity (nCi/g tissue)
Liver Epididymal fat
[1-14C]glycerol (500 mg; 9μCi) 8.20 5.90
[14C]polyglycerol (480 mg; 9.6μCi) 2.57 2.46
(85 mg; 8.9μCi) 1.10∗ 1.20∗
([14C]polyglycerol)PGPR (500 mg; 3.96μCi) 0.81∗ 1.31∗
([14C]stearic)PGPR (57 mg; 10.49μCi) a 46.1 82.9
b 34.1 76.2

a=fed overnight before dosing.b=starved overnight before dosing.∗=indicates samples 4 days after intubation, all other values are at 2 days.

Turnover of3H labelled PGPR

With the two [3H]PGPR preparations, excretion was incomplete with small amounts of radioactivity in the urine, faeces and expired water (Table 3). Only 4.8 or 11.6% of the dose was excreted in the faeces at 24 hr after dosing.

Table 7shows the nature of the lipid-soluble3H present in the tissues of rats 3–24 hr after dosing with either isomer of [3H]PGPR. Unchanged PGPR was found only in the stomach contents (3 hr after dosing), polyricinoleic acid was present in intestinal contents and faeces, and non-hydroxy and hydroxy fatty acids in the liver, fat and carcass. 30% of the3H in fat was hydroxy fatty acid . Assay of3H in urine showed 30% of the activity to be volatile and removed by freeze-drying. Less than 1% of the remaining activity was extractable into chloroform.

Table 7.Metabolites identified in tissues or tissue contents of rats 23–24 hr after an oral dose of [12-3H]PGPR or [9, 10-3H]PGPR

Time after dosing (hr) Tissue or tissue contents [12-3H]PGPR metabolites [9,10-3H]PGPR metabolites
3 Stomach contents PGPR PGPR
Lower small intestinal contents Polyricinoleic acid and free hydroxy fatty acids (5%) Polyricinoleic acid
Liver Hydroxy and non-hydroxy fatty acids
6 Caecal contents Free hydroxy fatty acids with 5% of non-hydroxy fatty acids and polyricinoleic acid
Liver Non-hydroxy fatty acids
Epididymal fat Non-hydroxy fatty acids (60%) and hydroxy fatty acids (40%)
24 Epididymal fat Non-hydroxy fatty acids (70%) and hydroxy fatty acids (30%)
   Carcass  Non-hydroxy fatty acids (70%) and hydroxy fatty acids (30%)  
   Faeces/caecal and rectal contents    Polyricinoleic acid and trace of non-hydroxy fatty acids

Groups of three rats were given a dietary slurry containing 3%3H-labelled PGPR and killed at 3, 6 and 24 hr later.

Distribution of3H in lipid and aqueous fractions of tissues of rats dosed with [12-3H]PGPR or [9,10-3H]PGPR

The results obtained with lipid-soluble3H, as presented inTable 6, show that 24 hr after dosing with tritiated PGPR, the entire contents of the alimentary tract contained less than 1% of the administered dose. At 24 hr, less than 0.5% of the dose was present in stomach tissue and less than 0.1% in small intestinal tissues. The3H content of the jejunum and upper ileum was greater than that of the duodenum or lower ileum, indicating a major site of absorption. Blood3H remained low (<0.1%/ml), while epididymal fat3H accounted for less than 5% of the dose. Liver3H also remained low (<0.1%/g).

Table 6.Tissue distribution of lipid-soluble3H at 3–24 hr after an oral dose of [12-3H]PGPR or [9,10-3H]PGPR

3H activity (μCi/g tissue) after intubation with
[12-3H]PGPR [9,10-3H]PGPR Tissue weight (g)
Time (hr) 3 6 12 24 3 6 12 24 [12-3H] PGPR [9,10-3H] PGPR
Stomach: 0.182 0.254 0.054 0.011 0.064 0.095 0.003 0.002 1.51 1.43
 tissue contents 5.545 2.764 0.088 0.007 1.487 0.449 0.101 0.062
Duodenum: 0.067 0.036 0.004 <0.001 0.033 0.034 0.001 <0.001 3.0 3.05
 tissue contents 0.081 0.096 0.006 0.001 0.053 0.043 0.053 0.035
Jejunum and upper ileum: 0.328 0.067 0.007 <0.001 0.118 0.028 0.001 <0.001 2.80 2.85
 tissue contents 0.467 0.143 0.003 <0.001 0.436 0.133 0.133 0.067
Lower ileum: 0.128 0.009 0.005 <0.001 0.105 0.016 <0.001 <0.001 2.95 2.45
 tissue contents 0.407 0.051 0.003 <0.001 0.433 0.145 0.102 0.082
Caecum/rectum: contents 0.307 0.199 0.294 0.041
Blood 0.008 0.006 <0.001 <0.001 0.002 0.002 0.001 <0.001
Epididymal fat 0.011 0.015 0.019 0.017 0.007 0.007 0.004 0.003 2.40 2.5
Liver 0.012 0.014 0.004 0.002 0.082 0.036 0.001 <0.001 10.95 11.05
Carcassalipid (aqueous) 1.205 0.300 0.295 0.332 0.270 0.277 0.260 0.099 2.19 2.15
           (5.893)  (5.440)  (7.093)  (7.413)    
 Brain  <0.001  <0.001  0.001  0.001  --  --  --  --    

Groups of three rats were killed at 3, 6, 12 and 24 hr after an oral dose of 2 ml dietary slurry containing 3%3H-labelled PGPR.aValue represents total lipid-soluble3H(μCi); those in parentheses represent water-soluble3H in total carcass.For doses seeTable 2, experiments 10/ and 11/.

The3H found in the aqueous phase of the carcass hydrolysate accounted for 75% of the dose, administered 24 hr earlier.

In vitro degradation of [12-3H]PGPR

Under the conditions used in the 2 or 3 hr of incubation, 10, 6, 12–15 and 40% of [12-3H]PGPR was degraded to polyricinoleic acid and free ricinoleic acid by the gut contents, intestinal mucosa, rat pancreas and hog pancreatic lipase, respectively.3H activity was not found in the aqueous extracts of these reaction mixtures, apart from the gut contents, for which less than 0.1% was recovered in the aqueous phase. No evidence of degradation was obtained with the boiled biological preparations.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): low bioaccumulation potential based on study results
Conclusions for polyglycerol (called Polyglycerine-Heavy in Justification document) include: 1) diglycerol and triglycerol are rapidly excreted unchanged in the urine, 2) tetraglycerol and highers are rapidly excreted unchanged in the feces and 3) polyglycerol polyricinoleate (PGPR) is metabolized to polyglycerol and therefore mammalian toxicity studies on PGPR are applicable for demonstrating the lack of toxicity due to PGPR (Note: there are subchronic tox studies on PGPR which have demonstrated that PGPR causes fatty livers which are believed to be due to metabolism of polyricinoleate and ricinoleic acid).
Executive summary:

Samples of the emulsifier polyglycerol polyricinoleate (PGPR) were synthesized using the radiolabelled precursors [1-14C]glycerol

([14C]polyglycerol PGPR), [9,10-3H] or [12-3H]ricinoleic acid ([3H] PGPR) or [1-14C]stearic acid ([14C]stearyl PGPR). The absorption, tissue

distribution, metabolism and excretion of these14C- or tritium-labelled PGPR samples administered to rats was studied. The effects of intestinal

and porcine pancreatic lipases on PGPR preparations were examined. Rats were dosed with [1-14C]glycerol, [14C]polyglycerol and

([14C]polyglycerol) PGPR by gavage and their urine, faeces and expired CO2monitored for14C. The results from the [1-14C]glycerol treated

animals showed extensive metabolism of glycerol. For [14C]polyglycerols, the lower polyglycerols were preferentially absorbed from the

intestine and were excreted unchanged in the urine while the higher polyglycerols were found in the faeces. After 4 days, 93% of the dose of

polyglycerols was recovered, of which some 30% was found in the urine and 60% in the faeces. Traces of14C activity were found in depot fat

and liver. The excretory pattern and urinary metabolites from ([14C]polyglycerol) PGPR was very similar to that of [14C]polyglycerol. Analysis

of urinary and faecal14C material indicated that the PGPR polymer was digested to give free polyglycerol (called Polyglycerine-Heavy in

Justification document) and polyricinoleic acid. PGPR was synthesised incorporating [1-14C]stearic into polyricinoleic acid which was then

esterified with polyglycerol. The resulting [14C]PGPR or [1-14C] stearic acid in a dietary slurry was administered to groups of fed or starved

rats by gavage. The results indicated complete digestion of PGPR and absorption of the fatty acids. The14C-material absorbed was extensively

laid down in depot fat and some metabolism to14CO2was demonstrated. The fate of the stearic acid was similar whether dosed alone or

incorporated into the PGPR polymer. Samples of PGPR were synthesized containing3H-labelled ricinoleic acid. The resulting [3H]PGPR was

intubated into rats as a component of a dietary slurry. The results indicated that the polymer is extensively digested and 90% of the administered

tritium is absorbed. The absorbed material was extensively metabolized within 24 hr so that large amounts of tritium were present in the

aqueous phase of the tissues examined. After 24 hr, less than 5% of the administered material was present as lipid material, of which a large

proportion was as non-hydroxy fatty acids. No traces of polymer material were found in the tissues examined. In vitro digestion of PGPR by

porcine pancreatic lipase and rat intestinal fractions was demonstrated. The results indicate very extensive digestion of the PGPR polymer to

polyglycerols (called Polyglycerine-Heavy in Justification document) and fatty acids. The fatty acids are metabolized extensively. The mono-,

di- and triglycerols are extensively absorbed from the intestinal tract and rapidly excreted in the urine unchanged but the hexa-, penta- and

higher polyglycerols are essentially not absorbed and excreted in the faeces unchanged.

 


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