Impulse Lecture “Phyllobilins – An Underexplored Family of Natural Products at the Center of a Scientific and Personal Journey”

Despite the rising popularity of herbal remedies and improved phytochemical profiling, the active principles of many phytotherapeutics are not completely understood. The focus of my research lies on phyllobilins, a compound class derived from the degradation of chlorophyll, which have remained overlooked as bioactive ingredients in medicinal plants for a long time. Despite their discoveries in the late nineties, potential bioactivities, and contributions to efficacies of phytomedicines have been disregarded. Among this natural product family, yellow phyllobilins (phylloxanthobilins, PxBs) in particular, which are known to play a part in the autumn colors [1], possess pharmaceutically relevant bioactivities: PxBs were recently shown to contribute to the effects of stinging nettle, having potent anti-oxidative and anti-inflammatory effects [2].

Once the active ingredient(s) is identified, the investigation of the mode of action as well as direct targets remains a challenge. In a functional screening of cancer cells, the cytoskeletal protein actin was identified as the first human target for PxB [3]; actin as target is involved in the anti-cancer activity of PxB, which has been demonstrated earlier [4]. The investigated bioactivities and the identification of a protein target in human cells open the door for the thorough study and relevance of this diverse natural product family in medicinal plants.

In this impulse lecture, the scientific path from the discovery of chlorophyll degradation products in higher plants and elucidation of their structure, to eventually unraveling the first results on their bioactivities is outlined.

Publication History

Article published online:
16 November 2023

• References

• 1 Moser S, Ulrich M, Muller T. et al. A yellow chlorophyll catabolite is a pigment of the fall colours. Photochem Photobiol Sci 2008; 7: 1577-1581
• 2 Karg CA, Doppler C, Schilling C. et al. A yellow chlorophyll catabolite in leaves of Urtica dioica L.: An overlooked phytochemical that contributes to health benefits of stinging nettle. Food Chem 2021; 359: 129906
• 3 Karg CA, Wang S, Al Danaf N, Pemberton RP, Bernard D, Kretschmer M, Schneider S, Zisis T, Vollmar AM, Lamb DC, Zahler S, Moser S. Tetrapyrrolic Pigments from Heme- and Chlorophyll Breakdown are Actin-Targeting Compounds. Angew Chem Int Ed 2021; 60: 22578
• 4 Karg CA, Wang P, Kluibenschedl F. et al. Phylloxanthobilins are Abundant Linear Tetrapyrroles from Chlorophyll Breakdown with Activities Against Cancer Cells. Eur J Org Chem 2020; 4499-4509