abstract
Salma Halime 5 rue Bommel, Z.A.E. Robert Steichen, L-4940 Hautcharage, Luxembourg Legumes are widely cultivated worldwide and valued for their role in sustainable soil fertilization and as a source of locally produced, plant-based protein. These crops are rich in bioactive compounds with beneficial effects for humans, animals, and the environment. Among these, saponins are of particular interest due to their antifungal, insecticidal, and health-promoting properties. This study investigates saponin mixtures extracted from legume harvest residues as sustainable alternatives to synthetic fungicides. Harvest residues from six legume species—soybean (Glycine max), pea (Pisum sativum), faba bean (Vicia faba), alfalfa (Medicago sativa), narrow-leafed lupin (Lupinus angustifolius), and white lupin (L. albus) were analyzed by UHPLC-MS/MS, identifying over 220 distinct saponins. Extracts exhibiting the most diverse saponin profiles were selected for in vitro antifungal assays against Fusarium graminearum, F. poae, Zymoseptoria tritici, and Botrytis cinerea, using microplate-based viability assays with resazurin, followed by spectrophotometric reading and CE₅₀ determination. Results demonstrated significant inhibitory activity against F. graminearum and F. poae for extracts from narrow-leafed lupin, white lupin, and alfalfa. In contrast, extracts from soybean, pea, and faba bean showed no measurable inhibitory effect. A similar pattern was observed for Z. tritici. For B. cinerea, even the highest extract concentrations failed to inhibit growth; instead, a stimulation of fungal growth was noted. These findings highlight legume harvest residues as a promising renewable resource for developing natural biopesticides. Future work will correlate antifungal efficacy with specific saponin compositions and test the extracts in planta, advancing circular bioeconomy strategies through valorization of agricultural waste.
I would like to thank the National Research Fund of Luxembourg for supporting the research project (TASSILI) of which my PhD project is a part (project reference: O22/17207949).
