Germinated cluster bean seeds: enhanced α-amylase inhibition and metabolomic insights for diabetes management

Abstract

This study examines the metabolomic profiles and bioactive properties of raw and germinated cluster bean (Cyamopsis tetragonoloba) seeds, focusing on their α-amylase inhibitory activity. A key element of diabetes management is inhibition of α-amylase, which delays the breakdown of starch into glucose and lowers postprandial blood glucose spikes. Plant-derived α-amylase inhibitors have health benefits and are safer than manufactured medications that have adverse effects from prolonged use. Metabolomic analysis revealed 108 compounds in raw seeds and 124 in germinated seeds, with 18 shared compounds showing high similarity (> 70%). These compounds include phytochemicals, amino acids, peptides, lipids, and carbohydrates. Raw seeds displayed higher total phenolic content, and antioxidant activity (DPPH: 82.91 ± 0.13%, ABTS: 85.56 ± 1.02%, FRAP: 62.50 ± 0.00 mg/g ascorbic acid equivalents) compared to germinated seeds. However, germination significantly increased α-amylase inhibitory activity (IC₅₀: 0.75 mg/mL vs. 7.00 mg/mL in raw seeds). Furthermore, peptides revealed from metabolomics profile and exhibiting peptide ranking scores > 0.5 were evaluated using ADMET and molecular docking studies. From the evaluated peptides, maculosin noted from germinated seeds exhibited strong binding affinity (-7.4 kcal/mol) to human pancreatic α-amylase, comparable to acarbose (-7.6 kcal/mol), and high human intestinal absorption. These results highlight germinated cluster bean seeds as a rich source of natural α-amylase inhibitors, with potential applications in diabetes management.