A green approach for genistein and apigenin extraction optimization from by-products of soybean crops

Soybeans’ genistein and its isomer apigenin are widely studied bioactive compounds owing to their therapeutic potential for treating various health disfunctions. A green extraction of both from soy by-products could lead to a valuable and sustainable approach to adding value to these materials in a biorefinery context. Here Hansen Solubility Parameters (HSP) and the Conductor-like Screening MOdel for Real Solvents (COSMO-RS) were applied to screen green molecular solvents and Natural Eutectic Solvents for the extraction of genistein and apigenin from soy by-products. The predicted solubilities of genistein and apigenin in 18 shortlisted candidates were experimentally tested by dynamic maceration, the most industrially implemented natural products extraction technique. EtOH:H2O (8:2, v/v) and natural eutectic solvent (NAES) betaine:ethylene glycol (1:2, mol/mol) showed the highest performance. These were selected for extraction optimizations by Design of Experiments from soy branches, the largest by-product by mass. The optimum condition of each solvent was applied to extract all other parts of soy collected post-mechanical harvesting. The highest value of apigenin, 591.49 ± 26.7 μg/g, was achieved from soy pods with EtOH:H2O (8:2, v/v), while the highest of genistein, 54.04 ± 3.39 μg/g, was achieved from soybeans using the same solvent. Our findings highlight the necessity of exercising caution when interpreting in silico outcomes in the context of metabolite extractions from complex matrices. A trade-off between in silico solvent screening and experimental work should be followed when developing new phytochemical extraction processes. Furthermore, soy by-products emerged as competitive candidates for a long-term source of the bioactive apigenin in a biorefinery context.