2-hydroxymethyl-9-methyl-6-(1-methylethyl)-1,4-dioxaspiro[4.5]decane

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:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: Pre-GLP and pre-OECD test guideline study

Data source

Reference

Reference Type:

publication

Title:

Biotransformation of (-)-menthone by human liver microsomes

Author:

Miyazawa M, Nakanishi K

Year:

2006

Bibliographic source:

PMID: 16717432 Biosci Biotechnol Biochem 70(5):1259-61

Materials and methods

Objective of study:

metabolism

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Examination of the metabolism of l-menthone by human liver microsome.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

L-menthan-3-one

EC Number:

237-926-1

EC Name:

L-menthan-3-one

Cas Number:

14073-97-3

IUPAC Name:

2-isopropyl-5-methylcyclohexanone

Constituent 2

Reference substance name:

(-)-menthone

IUPAC Name:

(-)-menthone

Details on test material:

- Name of test material (as cited in study report): (-)-menthone

Radiolabelling:

no

Administration / exposure

Doses / concentrations

Remarks:

Doses / Concentrations:
200 µM

Details on study design:

The standard reaction mixture contained liver microsomes (0.1 mg of proteins/mL) and 200 µM L-menthan-3-one in a final volume 0.50 mL of 100 mM potassium phosphate buffer (pH 7.4) containing an NADPH-generating system (0.5 mM NADP+, 5 mM glucose 6-phosphate and 0.5 units of glucose phosphate dehydrogenase/mL). The reaction mixture was incubated at 37 °C for 60 min, terminated by centrfugation at 3,000 rpm for 5 min and used for analysis with GC-MSfor identification of the metabolites. Areaction system without microsomes was also prepares for a blank experiment. No metabolites were detected.

Results and discussion

Metabolite characterisation studies

Metabolites identified:

yes

Details on metabolites:

On incubation of L-menthan-3-one with human liver microsomes in the presence of an NADPH-generating system, d-neomenthol and 7-hydroxymenthone were detected by GC-MS analysis.

Applicant's summary and conclusion

Conclusions:

L-menthan-3-one metabolise by human liver microsomes into d-neomenthol and 7-hydroxymenthone. The Km and Vmax values for the metabolized L-menthan-3-one to respective neomenthol and 7-hydroxymenthone by liver microsomes of human sample were 0.37 mM and 4.91 nmol/min/mg protein and 0.07 mM and 0.71 nmol/min/mg protein.

Executive summary:

The aim of the current study was to investigate the metabolism of L-menthan-3-one by liver microsomes of humans. L-menthan-3-one was metabolized to d-neomenthol (3-reduction) and 7-hydroxymenthone by human liver microsomes. The metabolites formed were analyzed on GC and GC-MS. Kinetic analysis showed that K(m) and V(max) values for the metabolized L-menthan-3-one to respective d-neomenthol and 7-hydroxymenthone by liver microsomes of human sample HG70 were 0.37 mM and 4.91 nmol/min/mg protein and 0.07 mM and 0.71 nmol/min/mg protein