Extraction, identification, and structure-activity relationship of antioxidative and α-amylase inhibitory peptides from cumin seeds (Cuminum cyminum)

Cumin seed-derived peptides were extracted, fractionated, and identified in this study. The three novel peptides produced were named as CSP1 (FFRSKLLSDGAAAAKGALLPQYW), CSP2 (RCMAFLLSDGAAAAQQLLPQYW), and CSP3 (DPAQPNYPWTAVLVFRH). These peptides exhibited different bioactivity potencies at 100 µg. CSP1 showed the highest ferric-reducing antioxidant power (FRAP) activity (36.71 mM) and α-amylase inhibition (24.54%) but relatively low radical scavenging activity (3.88%DPPHsc). CSP2 appeared to be an effective di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium (DPPH) radical scavenger (58.64%) with a FRAP value of 29.16 mM but showed poor inhibition against α-amylase (7.22%). CSP3 exhibited the lowest DPPHsc activity of 3.43%, with a FRAP value of 7.6 mM and α-amylase inhibition of 12.52%. The IC50 values of CSP1, CSP2, and CSP3 were 0.04, 0.002, and 0.05 µM, respectively, in the DPPH radical scavenging assays, as well as 0.02, 0.04, and 0.03 µM, respectively, for α-amylase inhibitory activity. A structure-activity relationship study (SAR) was also conducted to evaluate the inhibition mechanism.