Relaxing effects of Valeriana officinalis extracts on isolated human non‐pregnant uterine muscle

Objectives This study investigated the relaxing effects of Valeriana officinalis L. (Valerianaceae) on human uterine muscle. The major uses of this species in Europe are as a sedative and an anxiolytic; it is also used as a spasmolytic to treat gastrointestinal spasm. Methods We evaluated two valerian extracts (ethanolic and aqueous) in comparison with a natural mixture of valepotriates and nifedipine on spontaneous and agonist‐induced contractions in non‐pregnant human myometrium in vitro. Qualitative and quantitative chemical analysis was used to correlate the chemical composition of extracts with their spasmolytic effects. Myometrial strips were obtained from hysterectomy specimens of premenopausal women. Longitudinal muscle strips were mounted vertically in tissue baths under physiological conditions to record their isometric contraction. The responses of cumulative concentrations of valerian extracts on spontaneous contractions in the presence and absence of the β‐adrenoceptor blocker atenolol or the cyclooxygenase inhibitor indometacin, and on agonist‐induced contractions, were investigated. Key findings Valerian extracts and valepotriates inhibited uterine contra***ctility in a concentration‐dependent manner. Pretreatment with either atenolol or indometacin did not affect the uterine responses to valerian extracts. Valerian extract reduced the maximal contractile response induced by acetylcholine, phenylephrine and histamine independent of the stimulus. Conclusions Valerian extracts may have direct inhibitory effects on the contractility of the human uterus and this justifies the traditional use of this plant in the treatment of uterine cramping associated with dysmenorrhoea.