Immune effects of Viola tricolor

Viola tricolor is a medicinal plant with documented application as an anti-inflammatory herb. It contains relatively high levels of cyclotides, a protein with immunomodulatory activity. It is quite stable, and so could potentially have oral application as a medicine. For example, in inflammatory autoimmune intestinal diseases, for which the usual immunosuppressive drugs have some limitations, such as unwanted side effects, non-response and high cost.

In this study, we therefore investigated the effects of different Viola tricolor preparations (organic solvent extracts, aqueous preparations, and an enriched cyclotide preparation we optimised) on primary human T lymphocytes and macrophages. These are known to play a role in the aforementioned diseases. In particular, this concerns the balance in cytokine production of these cells.

All preparations we investigated showed a significant suppressive effect on the production of the relevant IL-21 cytokine by T lymphocytes. Thereby, the hot water preparations were most effective (and the longer boiled, the better). Similarly, the secretion of relevant cytokines by macrophages was inhibited by the extracts, with the cyclotide-enriched organic extract proving most effective. This could mean that this could counteract the inflammatory response in IBD.

With this pharmacological exploration of defined Viola preparations, we contribute to the development of new and alternative multi-target treatment strategies for multifactorial autoimmune diseases.




Viola tricolor