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Peptides have emerged as key regulators in various physiological processes, including growth, development, stress, and defense responses within plants as well as ecological interactions of plants with microbes and animals. Understanding and harnessing plant peptides can lead to the development of innovative strategies for crop improvement, increasing agricultural productivity, and enhancing resilience to environmental challenges such as drought, pests, and diseases. Moreover, some plant peptides have shown promise in human health applications, with potential therapeutic benefits as ingredients in herbal medicines as well as novel drug leads. The exploration of plant peptides is essential for unraveling the mysteries of plant biology and advancing peptide drug discovery. This short personal commentary provides a very brief overview about the field of plant-derived peptides and a personal word of motivation to increase the number of scientists in pharmacognosy working with these fascinating biomolecules., Competing Interests: The authors declare that they have no conflict of interest., (The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commecial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/).)

Viola tricolor is a medicinal plant with documented application as an anti-inflammatory herb. The standard of care for the treatment of inflammatory bowel disease is immunosuppressive therapeutics or biologics, which often have undesired effects. We explored V. tricolor herbal preparations that are rich in an emerging class of phytochemicals with drug-like properties, so-called cyclotides. As an alternative to existing inflammatory bowel disease medications, cyclotides have immunomodulatory properties, and their intrinsic stability allows for application in the gastrointestinal tract, for instance, via oral administration. We optimized the isolation procedure to improve the yield of cyclotides and compared the cellular effects of violet-derived organic solvent-extracts, aqueous preparations, and an isolated cyclotide from this plant on primary human T lymphocytes and macrophages, i.e., cells that are crucial for the initiation and progression of inflammatory bowel disease. The hot water herbal decoctions have a stronger immunosuppressive activity towards proliferation, interferon- γ , and interleukin-21 secretion of primary human T cells than a DCM/MeOH cyclotide-enriched extract, and the isolated cyclotide kalata S appears as one of the active components responsible for the observed effects. This effect was increased by a longer boiling duration. In contrast, the DCM/MeOH cyclotide-enriched extract was more effective in reducing the levels of cytokines interleukin-6, interleukin-12, interleukin-23, tumor necrosis factor- α , and C - X-C motif chemokine ligand 10, secreted by human monocyte-derived macrophages. Defined cyclotide preparations of V. tricolor have promising pharmacological effects in modulating immune cell responses at the cytokine levels. This is important towards understanding the role of cyclotide-containing herbal drug preparations for future applications in immune disorders, such as inflammatory bowel disease., Competing Interests: The authors declare that they have no conflict of interest., (The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commecial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/).)

Abnormalities in the process of uterine muscle contractility during pregnancy and birth can have major clinical implications, including preterm labour, which is the single largest cause of maternal and prenatal mortality in the Western world and a major contributor to childhood developmental problems. In contrast, induction of labour may be necessary in certain conditions. Currently used interventional therapies to suppress (tocolytic agents) or to induce (uterotonic agents) uterine contractions lack potency and/or selectivity and can have harmful side effects for mother and baby. Nature's diversity has always been, and still is, one of the biggest resources of therapeutic lead compounds. Many natural products exhibit biological activity against unrelated targets, thus providing researchers with starting points for drug development. In this review we will provide an overview of uterine muscle physiology, describe currently available biological screening procedures for testing of uterotonic plant compounds and will summarise traditionally-used uterotonic plants, their active components and their mechanisms, primarily focusing on uterotonic active circular plant peptides called cyclotides. Finally we will comment on the discovery of novel cyclotide-producing plant species and the possibility for the development of novel plant-derived uterotonic and tocolytic drugs., (© Georg Thieme Verlag KG Stuttgart · New York.)