Pin-2(3)-ene

Basic toxicokinetics

Administrative data

Endpoint:

basic toxicokinetics in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1980

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Well described study giving reliable information on several terpenes in vivo metabolism in rabbit.

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1981

Materials and methods

Objective of study:

metabolism

Principles of method if other than guideline:

Albino rabbits were orally administered test item and urine was collected for 3 days for identification of urinary metabolites.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Pin-2(3)-ene

EC Number:

201-291-9

EC Name:

Pin-2(3)-ene

Cas Number:

80-56-8

Molecular formula:

C10H16

IUPAC Name:

2,6,6-trimethylbicyclo[3.1.1]hept-2-ene

Test material form:

liquid

Radiolabelling:

no

Test animals

Species:

rabbit

Strain:

other: albino (Japanese White)

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Miyamoto Jikken Dobutsu, Hiroshima, Japan
- Weight at study initiation: 2-3 kg
- Fasting period before study: for 2 days before experiment
- Individual metabolism cages: yes
- Diet (e.g. ad libitum): Oriental RC-4, ad libitum
- Water (e.g. ad libitum): ad libitum

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

other: 100 mL water containing 0.1 g Tween 80

Details on exposure:

Rabbits were administered 20 mL solution through stomach tube followed by 20 mL water, corresponding to 400-700 mg/kg bw.

Duration and frequency of treatment / exposure:

Once

Doses / concentrations

Remarks:

Doses / Concentrations:
400-700 mg/kg bw

No. of animals per sex per dose / concentration:

6

Control animals:

no

Positive control reference chemical:

None

Details on study design:

None

Details on dosing and sampling:

The urine was collected daily for 3 days after drug administration and stored at 0-5°C until time of analysis.

Extraction of urinary metabolites:
The urine was adjusted to pH 4.7 with acetate buffer and incubated with beta-glucuronidase-arylsulfatase (3 mL/1000 mL of the fresh urine) at 37°C for 48 h, followed by continuous ether extraction for 48 h. The ether extracts were washed with 5% NaHCO3 and 5% NaOH to remove the acidic and phenolic fractions, respectively, and dried (magnesium sulfate). Ether was evaporated under reduced pressure to give neutral metabolites. The neutral metabolites were chromatographed on a column containing 100 g of silicic acid (200 mesh). Elution was started with n-hexane, and n-hexane-ethyl acetate mixtures (95:5, 90:10, 85:15, 70:30, and 50:50) were used as subsequent eluents. The acidic metabolites were recovered from the sodium bicarbonate layer by acidification with 5% HCl, followed by ether extraction. The ether extracts were esterified with diazomethane in ether or with dimethyl sulfate in the presence of potassium carbonate in anhydrous acetone. These esters of the acidic metabolites also were chromatographed in the same manner as the neutral metabolites.

Identification of urinary metabolites:
Purification by silicic acid gave pure metabolites. When necessary, metabolites were isolated by preparative TLC or GLC. Structure determination or identification was based on spectral data and chemical transformations.

Statistics:

None

Results and discussion

Preliminary studies:

None

Toxicokinetic / pharmacokinetic studies

Details on absorption:

None

Details on distribution in tissues:

None

Details on excretion:

None

Metabolite characterisation studies

Metabolites identified:

yes

Details on metabolites:

The main urinary metabolite from (+)-, (-)-, and (+/-)-alpha-pinenes was (-)-trans-verbenol.

Any other information on results incl. tables

None

Applicant's summary and conclusion

Conclusions:

The main urinary metabolite from (+)-, (-)-, and (+/-)-alpha-pinenes was (-)-trans-verbenol.

Executive summary:

The biotransformation of (+)-, (-)-, and (+/-)-alpha-pinene was studied in albino rabbits orally administered 400-700 mg/kg bw of the respective alpha-pinenes in water with 0.1% Tween 80. Urine was collected daily for 3 days and urinary metabolites were identified. In this study, the main urinary metabolite from (+)-, (-)-, and (+/-)-alpha-pinenes was (-)-trans-verbenol.