(1S)-3,7,7-trimethylbicyclo[4.1.0]hept-3-ene

Basic toxicokinetics

Administrative data

Endpoint:

basic toxicokinetics in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

No data

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study well documented, meets generally accepted scientific principles, acceptable for assessment

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:

Human metabolism of Δ3-carene and renal elimination of Δ3-caren-10-carboxylic acid (chaminic acid) after oral administration.

Author:

Schmidt L, Belov VN and Göen T.

Year:

2015

Bibliographic source:

Arch Toxicol. 89(3):381-392.

Materials and methods

Objective of study:

metabolism

Principles of method if other than guideline:

Metabolism of Δ3-carene was studied in volunteers.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

3,7,7-trimethylbicyclo[4.1.0]hept-3-ene

EC Number:

236-719-3

EC Name:

3,7,7-trimethylbicyclo[4.1.0]hept-3-ene

Cas Number:

13466-78-9

Molecular formula:

C10H16

IUPAC Name:

3,7,7-trimethylbicyclo[4.1.0]hept-3-ene

Test material form:

liquid

Radiolabelling:

no

Test animals

Species:

human

Sex:

male/female

Administration / exposure

Route of administration:

other: oral

Duration and frequency of treatment / exposure:

Single dose

Doses / concentrations

Remarks:

Doses / Concentrations:
10 mg

No. of animals per sex per dose / concentration:

Four healthy human volunteers

Details on dosing and sampling:

TEST ITEM ADMINISTRATION
- Four healthy human volunteers (3 men and 1 woman, mean age 33 ± 11 years, mean body weight 80 ± 8 kg) were orally exposed to ca 10 mg (ca 73 μmol, M = 136.23 mg/mmol) via spiked gelatin capsules.
- The volunteers ingested the capsules in the morning on an empty stomach, directly after the collection of one pre-exposure urine sample. After the exposure, they fasted for 1 h. During the remaining time of the experiment, they were allowed to eat and drink normally.

METABOLITE CHARACTERISATION STUDIES
- Tissues and body fluids sampled: Urine
- Time and frequency of sampling: Urine samples were collected by every volunteer throughout 24 h as often as possible. For every urine sample, the sampling time and the excretion volume were recorded.
- Storage: Urine samples were stored frozen under nitrogen protective gas at −20 °C until analysis.
- Method type(s) for identification: Gas chromatographic–mass spectrometric analyses (GC–PCI–MS and MS/MS); Concentration of the proposed CRN metabolites Δ3-caren-10-ol (CRN-10-OH), Δ3-caren-10-carboxylic acid (chaminic acid, CRN-10-COOH), and Δ3-caren-3,4-diol (CRN-3,4-OH) were determined using a very specific and sensitive GC–MS/MS procedure. Other CRN metabolites were investigated using GC–PCI–MS Q1 scan analyses.
- Urine samples were analysed according to the procedure of Schmidt et al. (2013).

Statistics:

None

Results and discussion

Main ADME results

Type:

metabolism

Metabolite characterisation studies

Metabolites identified:

yes

Details on metabolites:

- None of the volunteers reported any negative or physiological effects due to the exposure. Some mentioned a distinct smell of the exhaled breath, which vanishes rapidly, about 1–2 h after exposure. In total, 71 samples from four human volunteers were analysed.
- Renal excretion of CRN-10-COOH in the pre-exposure samples was 2.8 ± 1.4 μg/h. The urinary CRN-10-COOH concentration increased distinctly within 1–3.5 h after oral administration to maximum levels of 113.0–1172.9 μg/L (19.6–68.8 μg/h) and declined afterwards to the base levels within the 24-h observation period. The conjugation shares of CRN-10-COOH in the excretion maximum ranged between 94 and 97 % of the metabolite concentration. Whereas CRN-10-OH and CRN-3,4-OH were not detected in any of the samples.
- Renal excretion kinetics of CRN-10-COOH showed an elimination half-life of about 3 h. The cumulative excretion of CRN-10-COOH within 24 h after exposure correlated with about 2 % of the applied dose.
- At the end of the observation time, a slight elevation of the cumulative excretion amount of CRN-10-COOH was determined in the urine of two volunteers.

Analysis of unknown (+) 3 carene metabolites in urine
Since only about 2 % of the oral dose was excreted as CRN-10-COOH and, moreover, CRN-10-OH and CRN-3,4-OH were not found to be relevant human urinary metabolites, samples were analysed for further unknown major metabolites using GC–PCI–MS Q1 full scans. These analyses revealed six characteristic peaks of unknown urinary CRN metabolites. The percentages of the total renal metabolite excretion were estimated to be about 3 % (CRN-M1), 1 % (CRN-M2), 5 % (CRNM3), 4 % (CRN-M4), 11 % (CRN-M5), and 2 % (CRNM6), respectively.

Any other information on results incl. tables

Table 7.1.1/1: Data on the renal excretion kinetics of 3-caren-10-carboxylic acid after oral intake of 10 mg (+)-3-carene by four healthy human volunteers

 

Parameters	Unit	Mean	SD	Min	Max
Dose	μmol	75.5	5.0	68.9	78.2
RE,max	μg/h	40.0	21.7	19.6	68.8
tmax	h	2.4	1.4	0.9	3.5
t1/2	h	3^a(3)^b	<1^a(2)^b	2^b	5^b
AUC0→tf	μmol	1.0^a(1.3)^b	<0.1^a(0.5)^b	0.9^b	1.9^b
Vtotal	L	1.6	0.7	1.0	2.5

 

R_E,max maximum renal excretion; t_max time to reach maximum renal excretion; t_1/2 elimination half-life; AUC_0→tf area under the renal excretion vs. time curve (from time 0 to final sampling timetf);V_total summarized excreted urine volume

a Values calculated from the log-normal fitted mean renal elimination curve (n=4)

b Values calculated from the individual excretion data

Applicant's summary and conclusion

Conclusions:

The results of the study indicate that CRN-10-COOH is a relevant product of the human in vivo metabolism of delta-3-carene.

Executive summary:

In a metabolism study, four healthy human volunteers were orally exposed to a single dose of 10 mg delta-3 -carene [(+)-delta-3-carene] via spiked gelatin capsules. Each volunteer gave one urine sample before administration and subsequently collected each urine sample within 24 h after administration. The concentration of the proposed CRN metabolites delta-3-caren-10-ol (CRN-10-OH), delta-3 -caren-10-carboxylic acid (chaminic acid, CRN-10-COOH), and delta-3-caren-3,4-diol (CRN-3,4-OH) were determined using a very specific and sensitive GC-MS/MS procedure. Other CRN metabolites were investigated using GC-PCI-MS Q1 scan analyses.

CRN-10-COOH was detected in each urine sample with maximum concentration (113.0-1172.9 µg/L)) 2-3 h after administration, whereas CRN-10-OH and CRN-3,4-OH were not detected in any of the samples. The renal excretion kinetics of CRN-10-COOH showed an elimination half-life of about 3 h. The cumulative excretion of CRN-10-COOH within 24 h after exposure correlated with about 2% of the applied dose. The GC-PCI-MS Q1 scan analysis indicated several additional human CRN metabolites: 3% (CRN-M1), 1% (CRN-M2), 5% (CRNM3), 4% (CRN-M4), 11% (CRN-M5), and 2% (CRNM6), respectively.

The results of the study indicate that CRN-10-COOH is a relevant product of the human in vivo metabolism of delta-3-carene.