Effects of 1.8-cineole on the α1,2 adrenoreceptors, the β-adrenergic and dopamine D2 receptors

Abstract

Stanislav Hristo, Martins Botev and Dimitar Stoichkov

Eucalyptus oil is frequently used in phytotherapy. The objective of the present paper was to investigate to what extent 1.8-cineole influences the activity of smooth muscle fibres. The effects of 1.8-cineole on the spontaneous contractile activity were investigated in in vitro experiments with circular smooth muscle fibres of guinea pig stomach. 1.8-cineole was found to have agonistic effects on the 1 and 2 adrenergic receptors. These effects can be registered at low concentrations of up to 3 × 10-7 to 2 × 10-5 M 1.8-cineole. At higher concentrations, the well-known spasmolytic effect appears. At concentrations above 4 × 10-4 M 1.8-cineole, the effect of 10-5 M acetylcholine is 100% suppressed. The results allow for the assumption that, besides the spasmolytic effects investigated to date and owing to its specific effects on the 2 adrenergic receptors of the nerve cells, 1.8-cineole brings about an additional improvement to local blood circulation and alleviates pain.