Influence of the chirality of (R)-(-)- and (S)-(+)-carvone in the central nervous system: a comparative study.
Level 5 - mechanism / opinion, no new human data
Preclinical animal research
PubMed 17299731 · doi:10.1002/chir.20379
What was done
The central nervous system (CNS) effects of the enantiomers (R)-(-)-carvone and (S)-(+)-carvone were evaluated and compared in mice. The investigators assessed acute toxicity (LD50), general behavioral depressant and antinociceptive profiles, ambulation over time, potentiation of pentobarbital-induced sleeping time (at 100 and 200 mg/kg), and anticonvulsant activity against seizures induced by pentylenetetrazol (PTZ) and picrotoxin (PIC).
What was found
The reported LD50 was 484.2 mg/kg (358.9–653.2) for (S)-(+)-carvone and 426.6 mg/kg (389.0–478.6) for (R)-(-)-carvone. Both enantiomers caused CNS depression, including decreased response to touch, decreased ambulation, sedation, palpebral ptosis, and antinociception. (R)-(-)-Carvone was more effective at reducing ambulation at 0.5 and 2.0 h post-administration, whereas (S)-(+)-carvone was slightly more potent at 1 h. In potentiating pentobarbital sleeping time, (R)-(-)-carvone was more effective at 100 mg/kg, but less potent than (S)-(+)-carvone at 200 mg/kg. At 200 mg/kg, (S)-(+)-carvone significantly increased the latency of convulsions induced by PTZ and PIC, while (R)-(-)-carvone showed no effect. Exact numerical values for behavioral scores, sleep duration, and convulsion latencies were not reported in the abstract.
Why it matters
The findings demonstrate that while both carvone enantiomers possess CNS depressant and sedative actions, their neuropharmacological profiles diverge stereospecifically with respect to anticonvulsant activity.
Limits
The study was conducted entirely in mice, precluding direct extrapolation to humans. The abstract does not disclose the sample size (n), control groups, or exact numerical values and p-values for the behavioral, sedative, and anticonvulsant assays.
Cited by
- supports The flavoring agents of dill and spearmint are enantiomers of the same molecule, carvone, differing only in optical rotation (R-carvone and S-carvone).