Antidepressant activity of a refined valerian extract – an interesting new feature

Preparations from Valeriana officinalis L.s.l. were traditionally used as mild sedatives, anxiolytics and hypnotics. However, despite numerous attempts, the mechanism of action is still discussed controversially. Sedative effects were studied in numerous investigations. However, neither in pharmacological nor in human studies these effects could be convincingly demonstrated. Only recently a comprehensive preclinical testing of the refined valerian extract phytofin Valerian 368 demonstrated in particular anxiolytic properties [1]. Because of the high comorbidity of anxiety, depressive and sleep disorders [2, 3], additional testing on potentially antidepressant effects of the valerian extract was performed.

In studies performed by Hattesohl [4] phytofin Valerian 368 (DER native 3–5:1; valerenic acids 0.12%), was tested to be effective at a dose of 250mg/kg bw/d in the Forced Swimming Test (acc. to Porsolt) using male CD-rats (n=12/group). In order to exclude false positive results two days before motility was determined in the Open Field Test. The motility was unchanged by the intake of the extract. As no increased locomotor activity was observed, false positive results could be excluded [4].

Because of the antidepressant activity in vivo, investigations concerning the mechanism of action in relation to neurotransmitter release were performed. The transporters for noradrenaline and serotonin are key targets for antidepressant drugs. Both noradrenaline-selective and serotonin-selective reuptake inhibitors are effective against major depression and other psychiatric illnesses [5]. Therefore, we investigated the effects of the refined extract phytofin Valerian 368 on neurotransmitter release in vitro. It showed weak inhibition of the serotonin transporter. In contrast, the inhibition of the noradrenaline transporter was pronounced even at low concentrations.

Data providing support for the hypotheses of amine receptor abnormalities in depression are reported by several authors and indicate the need for expanded studies of amine receptor density and function [6]. We analyzed the effects on serotonin- and noradrenalin-receptor density in different brain areas of rats treated with valerian.

In addition to the recently shown anxiolytic effects of phytofin Valerian 368, data supporting antidepressive effects could be demonstrated in in-vitro and ex-vivo experiments. The clear preclinical data encourage further testing in human pharmacological studies to establish this anti-depressive potential.

[1] Hattesohl M et al.: Phytopharmaka und Phytotherapie 2006– Forschung und Praxis, Berlin 28.-30.09.2006 [Poster]. Z Phytotherapie 2006; 27 (Kongressband): S24.

[2] Müller D et al.: Phytomedicine 2003; 10: 25–30.

[3] Neckelmann D et al.: Sleep 2007; 30: 873–880.

[4] Hattesohl M: Pharmakologische Untersuchungen zu Valeriana officinalis L.s.l. [Dissertation]. Universität Münster 2006.

[5] Humble M: Acta Psychiatr Scand Suppl. 2000; 402: 28–36.

[6] Gómez E, et al.: Actas Esp. Psiquiatr. 2001; 29: 186–194.