The influence of essential oil of aniseed (Pimpinella anisum, L.) on drug effects on the central nervous system.

Anise (Pimpinella anisum L.; Apiaceae) and its essential oil have been widely used in folk medicine, pharmacy and food industry. Since there are some data about the impact of anise on functions of central nervous system (CNS), the issue of possible interactions with drugs acting in CNS should be considered. This survey aimed to examine the influence of aniseed essential oil (EO) intake on the effects of drugs that act in CNS. The chemical profile of essential oil determined by GC-MS revealed as the main components: trans-anethole (88.49%), γ-himachalene (3.13%), cis-isoeugenol (1.99%), and linalool (1.79%). The effects of codeine, diazepam, midazolam, pentobarbital, imipramine and fluoxetine were tested in mice after 5days of peroral pretreatment with human equivalent dose of aniseed EO (0.3mg/kg). The intake of EO led to significant increase of analgesic effect of codeine. The motor impairment caused by midazolam was enhanced in the group treated by EO. The application of diazepam decreased the number and percentage of entries in open arm in elevated maze plus test in the group pretreated with EO indicating augmented effect of drug on motor activity. EO pretreatment caused significant shortage of pentobarbital induced sleeping time when compared to control. The decrease in antidepressant effect of imipramine and fluoxetine was diminished by the pretreatment with aniseed EO. Based on the results of this study we conclude that concomitant intake of aniseed EO preparations and drugs that act on CNS should be avoided due to potential herb-drug interactions, which also need further clinical confirmation.