Reaction product with n-butanol of high-boiling stream resulting from the hydroxylation, oxidative cleavage and hydrolysis of vegetable oil saturated and unsaturated C16-C22 triglycerides.

Basic toxicokinetics

Administrative data

Endpoint:

basic toxicokinetics in vitro / ex vivo

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Data source

Reference

Reference Type:

publication

Title:

Relative rates of hydrolysis by rat pancreatic lipase of esters of C2-C18 fatty acids with C1-C18 primary n-alcohols

Author:

Mattson F.H. and Volpenhein R.A.

Year:

1969

Bibliographic source:

Journal of Lipid Research, Volume 10, 1969

Materials and methods

Objective of study:

metabolism

Test guideline

Qualifier:

no guideline followed

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Fatty acids, C3-C16, butyl esters

IUPAC Name:

Fatty acids, C3-C16, butyl esters

Details on test material:

The esters of primary n-alcohols containing 1-18 carbons and fatty acids containing 2-18 carbons were prepared. The fatty acids were isolated from natural fats or purchased, while the alcohols were obtained from commercial sources. The fatty acids and alcohols and the esters synthesized from them were purified by appropriate distillation, crystallization, and column chromatography. Thin-layer and gas-liquid chromatography established that the starting materials and the final products were better than 99% pure.

Test animals

Species:

rat

Strain:

not specified

Sex:

not specified

Administration / exposure

Route of administration:

other: not applicable

Vehicle:

other: not applicable

Details on exposure:

not applicable: in vitro test

Duration and frequency of treatment / exposure:

not applicable: in vitro test

Doses / concentrations

Remarks:

Doses / Concentrations:
not applicable: in vitro test

No. of animals per sex per dose / concentration:

not applicable: in vitro test

Control animals:

other: not applicable

Details on study design:

The lipolytic enzymes, other than lipase, in rat pancreatic juice that had been freeze-dried were inactivated by keeping a pH 9 solution of reconstituted juice at 40°C for 1 hr. The activity of the enzyme preparation varied slightly from day to day. To correct for this we hydrolyzed replicate samples of methyl oleate each day. The values obtained that day for the other esters were corrected to a standard value for the methyl oleate. The rates of hydrolysis of the esters were determined with the aid of a pH-stat. The digestion mixture consisted of 225 pmoles of substrate (some exceptions are
noted later), 330 µmoles of CaC12, 7 pmoles of free oleic acid (this addition is discussed later), 17 mg of histidine (final concentration 0.002 M), 3.11 g of NaCl (final concentration 1 M), and 0.6 mg of selectively inactivated, lyophilized rat pancreatic juice in a total volume of 55 ml at pH 9.0 and at 25°C. The rate of stirring of the digestion mixture was such that a further increase in the amount of agitation did not cause an increase in the rate of enzymatic hydrolysis. The gas space in the flask was continuously flushed with C02-free, water-saturated nitrogen. If the digestion is carried out at pH 9 all of the resulting free fatty acids are titrated. This pH is within the broad pH optimum of this enzyme. For the majority of the substrates, the rate of the reaction was enzyme-limited under the digestion conditions described above. However, the water solubility of a few of the esters, where both the fatty acid and alcohol were short-chain, was greater than 225 µmoles per 55 ml. In these instances, the quantity of substrate was increased until the solubility limit was exceeded; thus, an interface was present. The level of ester then was raised until no further increase in the rate of hydrolysis was obtained; this level of substrate was used in determining the rate of hydrolysis. Thus all reactions were zero order with respect to substrate.

Statistics:

The values for the rates of hydrolysis of the esters are for the first few minutes after addition of the enzyme. After making a large number of measurements, we judge that a 10% difference between two rates is significant.

Results and discussion

Main ADME results

Type:

metabolism

Results:

Rat pancreatic lipase is hydrolysing butyl esters of fatty acids with differnet chain length with a rate of hydrolysis between 1.2 and 3.0 µeq/min/mg enzyme.

Metabolite characterisation studies

Metabolites identified:

not specified

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information): low bioaccumulation potential based on study results
Rat pancreatic lipase is hydrolysing butyl esters of fatty acids with differnet chain lengths with a rate of hydrolysis between 1.2 and 3.0 µeq/min/mg enzyme.

Executive summary:

The rate at which rat pancreatic lipase (glycerol-ester hydrolase, EC 3.1.1.3) hydrolyzes the esters of primary n-alcohols containing from 1 to 18 carbon atoms with fatty acids containing from 2 to 18 carbon atoms was determined. The speed of hydrolysis was influenced, apparently independently, by both the acyl and the alkyl chains. With respect to the fatty acid moiety, the esters of dodecanoic acid were usually split at the most rapid rate. Esters of butyric acid were the next most susceptible. In the case of the alcohol moiety, esters of heptyl alcohol were hydrolyzed most rapidly. On the basis of the pattern of the relative rates of hydrolysis, it is proposed that the influence of the alcohol component is a result of its orienting the ester molecule at the oil/water interface. The fatty acid effect is attributed to enzyme-substrate specificity.