Medicinal Plants to Treat Epilepsy: Discovery of Antiseizure Compounds by In Vivo Zebrafish Bioactivity-Guided Isolation

Epilepsy is a chronic neurological disorder characterized by recurrent epileptic seizures which affects 1% of the world's population, of whom 80% live in low- and middle-income countries. Antiseizure drugs (ASDs) and therapies are available for epilepsy management but despite these possibilities, a third of epileptic patients suffer from pharmaco-resistance. There is, therefore, an urgent need for new and cost-effective treatments to manage epilepsy. Herbs used in traditional medicine remain the first-line treatment for most people with limited access to ASDs. Thus, in this thesis, three plants traditionally used to treat epilepsy and CNS-related disorders were selected and studied using a bioactivity-guided isolation protocol combined to an in vivo zebrafish epilepsy model to effectively identify compounds with significant antiseizure activity. This work demonstrated the chemical diversity of antiseizure constituents and their mode of action which may help to provide evidence-based data for the management of epilepsy with well-selected medicinal herbs

Data from: A below ground herbivore shapes root defensive chemistry in natural plant populations

Plants display extensive intraspecific variation in secondary metabolites. However, the selective forces shaping this diversity remain often unknown, especially below ground. Using Taraxacum officinale and its major native insect root herbivore Melolontha melolontha, we tested whether below ground herbivores drive intraspecific variation in root secondary metabolites. We found that high M. melolontha infestation levels over the last decades are associated with high concentrations of major root latex secondary metabolites across 21 central European T. officinale field populations. By cultivating offspring of these populations, we show that both heritable variation and phenotypic plasticity contribute to the observed differences. Furthermore, we demonstrate that the production of the sesquiterpene lactone taraxinic acid β-D-glucopyranosyl ester (TA-G) is costly in the absence, but beneficial in the presence of M. melolontha, resulting in divergent selection of TA-G. Our results highlight the role of soil-dwelling insects for the evolution of plant defences in nature

A below-ground herbivore shapes root defensive chemistry in natural plant populations

Plants display extensive intraspecific variation in secondary metabolites. However, the selective forces shaping this diversity remain often unknown, especially below ground. Using Taraxacum officinale and its major native insect root herbivore Melolontha melolontha, we tested whether below-ground herbivores drive intraspecific variation in root secondary metabolites. We found that high M. melolontha infestation levels over recent decades are associated with high concentrations of major root latex secondary metabolites across 21 central European T. officinale field populations. By cultivating offspring of these populations, we show that both heritable variation and phenotypic plasticity contribute to the observed differences. Furthermore, we demonstrate that the production of the sesquiterpene lactone taraxinic acid β-d-glucopyranosyl ester (TA-G) is costly in the absence, but beneficial in the presence of M. melolontha, resulting in divergent selection of TA-G. Our results highlight the role of soil-dwelling insects for the evolution of plant defences in nature

Raw data of field sampling and offspring analysis

Raw data of field sampling and offspring analysi

Zebrafish-based identification of the antiseizure nucleoside inosine from the marine diatom Skeletonema marinoi

publishedVersio

Antiseizure potential of the ancient Greek medicinal plant Helleborus odorus subsp. cyclophyllus and identification of its main active principles

Ethnopharmacological relevance Ethnopharmacological data and ancient texts support the use of black hellebore (Helleborus odorus subsp. cyclophyllus, Ranunculaceae) for the management and treatment of epilepsy in ancient Greece. Aim of the study A pharmacological investigation of the root methanolic extract (RME) was conducted using the zebrafish epilepsy model to isolate and identify the compounds responsible for a potential antiseizure activity and to provide evidence of its historical use. In addition, a comprehensive metabolite profiling of this studied species was proposed. Materials and methods The roots were extracted by solvents of increasing polarity and root decoction (RDE) was also prepared. The extracts were evaluated for antiseizure activity using a larval zebrafish epilepsy model with pentylenetetrazole (PTZ)-induced seizures. The RME exhibited the highest antiseizure activity and was therefore selected for bioactivity-guided fractionation. Isolated compounds were fully characterized by NMR and high-resolution tandem mass spectrometry (HRMS/MS). The UHPLC-HRMS/MS analyses of the RME and RDE were used for dereplication and metabolite profiling. Results The RME showed 80% inhibition of PTZ-induced locomotor activity (300 μg/ml). This extract was fractionated and resulted in the isolation of a new glucopyranosyl-deoxyribonolactone (1) and a new furostanol saponin derivative (2), as well as of 20-hydroxyecdysone (3), hellebrin (4), a spirostanol glycoside derivative (5) and deglucohellebrin (6). The antiseizure activity of RME was found to be mainly due to the new furostanol saponin (2) and hellebrin (4), which reduced 45% and 60% of PTZ-induced seizures (135 μM, respectively). Besides, the aglycone of hellebrin, hellebrigenin (S34), was also active (45% at 7 μM). To further characterize the chemical composition of both RME and RDE, 30 compounds (A7-33, A35–37) were annotated based on UHPLC-HRMS/MS metabolite profiling. This revealed the presence of additional bufadienolides, furostanols, and evidenced alkaloids. Conclusions This study is the first to identify the molecular basis of the ethnopharmacological use of black hellebore for the treatment of epilepsy. This was achieved using a microscale zebrafish epilepsy model to rapidly quantify in vivo antiseizure activity. The UHPLC-HRMS/MS profiling revealed the chemical diversity of the extracts and the presence of numerous bufadienolides, furostanols and ecdysteroids, also present in the decoction