(1R,5R)-2,6,6-trimethylbicyclo[3.1.1]hept-2-ene

Endpoint summary

Link to relevant study record(s)

Reference

Endpoint:

basic toxicokinetics in vivo

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Objective of study:

metabolism

Qualifier:

no guideline followed

Principles of method if other than guideline:

- Principle of test: Albino rabbits were orally administered with test item and urine was collected for 3 days for identification of urinary metabolites.
- Short description of test conditions: see below
- Parameters analysed / observed: Determination and identification of urinary metabolites

GLP compliance:

no

Radiolabelling:

no

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
- Age at study initiation: no data
- Weight at study initiation: 2-3 kg.
- Housing: individual stainless steel metabolism cages
- Diet (e.g. ad libitum): Oriental RC-4, ad libitum
- Water (e.g. ad libitum): ad libitum

Route of administration:

oral: gavage

Vehicle:

other: 100 mL water containing 0.1 g Tween 80

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
The test item was suspended in water (100 ml) containing 0.1 g Tween 80 and were homogenized well.

Duration and frequency of treatment / exposure:

Rabbits were once administered 20 mL solution through stomach tube followed by 20 mL water, corresponding to 400-560 mg/kg bw.

Dose / conc.:

560 mg/kg bw/day

Remarks:

(maximum dose administered)

No. of animals per sex per dose / concentration:

6

Control animals:

no

Positive control reference chemical:

None

Details on dosing and sampling:

METABOLITE CHARACTERISATION STUDIES
- Tissues and body fluids sampled (delete / add / specify): urine
- Time and frequency of sampling: The urine was collected daily for 3 days after drug administration and stored at 0-5ºC until time of analysis.
- From how many animals: 6
- Method type(s) for identification: GLC-MS, TLC, NMR, IR
- Other:
Extraction and fractionation of urinary metabolites: The urine was centrifuged to remove feces and hairs at 0ºC, and the supernate was used for the experiments. The urine was adjusted to pH 4.76 with acetate buffer and incubated with β-glucuronidase-arylsulfatase (3 ml/1000 ml of the fresh urine) at 37ºC for 48 hr, followed by continuous ether extraction for 48 hr. The ether extracts were washed with 5% NaHC03 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% HCI, 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.

Metabolites identified:

yes

Details on metabolites:

The main urinary metabolite from (+) alpha-pinene was (-)-trans-verbenol.
As minor metabolites of (+) alpha-pinene, two allylic products, myrtenol and myrtenic acid, were obtained.

Conclusions:

The main urinary metabolite from (+) alpha-pinene was (-)-trans-verbenol.

Executive summary:

The biotransformation of (+)-alpha-pinene was studied in albino rabbits orally administered 400 -560 mg/kg bw of test item 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 (+)-alpha-pinene was (-)-trans-verbenol. Also, as minor metabolites of (+) alpha-pinene, two allylic products, myrtenol and myrtenic acid, were obtained.

Description of key information

Basic Toxicokinetics: Metabolism. The main urinary metabolite from (+) alpha-pinene was found to be (-)-trans-verbenol.

Additional information

Basic Toxicokinetics: Metabolism

Supporting study: The biotransformation of (+)-alpha-pinene was studied in albino rabbits orally administered 400 -560 mg/kg bw of test item 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 (+)-alpha-pinene was (-)-trans-verbenol. Also, as minor metabolites of (+) alpha-pinene, two allylic products, myrtenol and myrtenic acid, were obtained.