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Administrative data

Endpoint:
basic toxicokinetics in vitro / ex vivo
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Acceptable, well documented publication which meets basic scientific principles.

Data source

Reference
Reference Type:
publication
Title:
Hydrolysis of fully esterified alcohols containing from one to eight hydroxyl groups by the lipolytic enzymes of rat pancreatic juice.
Author:
Mattson, F.H. and Volpenhein, R.A.
Year:
1972
Bibliographic source:
J Lipid Res 13(3):325-328

Materials and methods

Principles of method if other than guideline:
The enzymatic hydrolysis in vitro of the esters of methanol, ethylene glycol, glycerol, erythritol, pentaerythritol, adonitol, sorbitol, and sucrose in which all alcohols groups were esterified with oleic acid was studied. Various preparations of rat pancreatic juice, including pure lipase, were used as the sources of enzymes.
GLP compliance:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
Methyl oleate
EC Number:
203-992-5
EC Name:
Methyl oleate
Cas Number:
112-62-9
Molecular formula:
C19H36O2
IUPAC Name:
methyl (Z)-octadec-9-enoate

Test animals

Species:
rat
Strain:
not specified
Sex:
not specified

Administration / exposure

Route of administration:
other: not applicable since in vitro test
Vehicle:
other: no
Duration and frequency of treatment / exposure:
not applicable since in vitro test
Doses / concentrations
Remarks:
Doses / Concentrations:
100 mg of each of the substrates.
No. of animals per sex per dose / concentration:
not applicable since in vitro test
Control animals:
no

Results and discussion

Metabolite characterisation studies

Details on metabolites:
The combination of bile-pancreatic fluid digested all substrates with the exception of sorbital hexaoleate and sucrose octaoleate.
Lipase (EC 3.1.1.3) did not hydrolyse compounds that contained more than three ester groups. Compounds containing four and five ester groups were hydrolysed by certain preparations of pancreatic juice; this activity is attributed to the enzyme, nonspecific lipase. This enzyme also hydrolysed esters of primary alcohols. The compounds containing six (sorbital) and eight (sucrose) ester groups were not hydrolysed.

Any other information on results incl. tables

The rate of hydrolysis of the esters of the eight different alcohols by the various preparations of rat pancreatic juice is given in the table below. The numbers in parentheses are the volume or weight of enzyme preparation that was used in that particular digest.

Table 1. Relative rates of hydrolysis by rat pancreatic juice enzymes of the complete oleate esters of the listed alcohols.

 

 

 

 

 

 

 

 

Pancreatic-Bile Juice

Untreated Pancreatic Juice

Treated Pancreatic Juicea

Purified Lipase

No TCb

No TC

TC added

No TC

TC Added

No TC

TC added

 

µmoles FFA min/mL

µmoles FFA min/mg

µmoles FFA min/mg

µmoles FFA min/mg

Methanol, 1e

54    (0.05)d

2.6 (1.2)

4.0 (1.2)

2.5 (1.2)

0 (1.2)

63 (0.02)

0 (0.3)

Ethylene glycol, 2

160 (0.025)

10  (0.3)

4.3 (0.3)

7.7 (0.3)

0 (0.3)

200 (0.01)

0 (0.1)

Glycerol, 3

2100 (0.005)

73 (0.075)

6.0 (0.15)

70 (0.06)

0 (0.3)

1900 (0.002)

0 (0.02)

Erythritol, 4

1.9   (1)

0   (6)

1.4 (3)

0 (6)

0 (6)

0 (0.1)

0 (0.1)

Pentaerythritol, 4

1.1   (2)

0   (6)

1.1 (3)

0 (6)

0 (6)

0 (0.1)

0 (0.1)

Adonitol, 5

0.53 (2)

0   (6)

0.25 (3)

0 (6)

 

0 (0.1)

0 (0.1)

Sorbitol, 6

0      (2)

0   (6)

0   (12)

0 (6)

0   (12)

0 (0.1)

0 (0.1)

Sucrose, 8

0      (2)

0   (6)

0   (12)

0 (6)

0   (12)

0 (0.1)

0 (0.1)

a Nonspecific lipase was inactivated by treatment with α-chymotrypsin.

b TC, Sodium taurocholate.

c Number of ester groups.

d The number in parentheses is the volume or weight of the enzyme preparation that was used.

The combination of bile-pancreatic fluid digested all substrates with the exception of sorbital hexaoleate and sucrose octaoleate. This failure of hydrolysis was obtained in spite of using 400 times as much combination bile-pancreatic

fluid as was used when triolein was the substrate. When pancreatic juice without bile was used as a source of the enzymes, the esters that were hydrolysed depended on the presence or absence of added sodium taurocholate.

In the absence of sodium taurocholate, only those substrates that contained less than four ester groups were hydrolysed. The addition of sodium taurocholate to the digest permitted the hydrolysis also of the substrates

containing four and five ester groups. There were marked differences in the rates of hydrolysis of the oleate esters

of methanol, ethylene glycol, and glycerol if taurocholate was not present, but these differences disappeared if this

bile salt was added to the digest. In the absence of sodium taurocholate, the pattern of digestion by treated

pancreatic juice. However, in the presence of added sodium taurocholate, pancreatic juice that had been treated

with the proteolytic enzyme could not digest any of the substrates. The final set of results was obtained with purified pancreatic lipase. If sodium taurocholate was not present, this enzyme hydrolysed methyl oleate, ethylene glycol dioleate, and triolein, but did not hydrolyse the substrates that contained more than three ester groups. The additions

of sodium taurocholate blocked completely the hydrolytic activity of this enzyme. 

Applicant's summary and conclusion