决明子乃决明（Cassia obtusifolia L.）的干燥成熟种子，被中医界用于治疗各种疾病。本研究探讨决明子水解产物的抗氧化活性和稳定性，并鉴定其中的短肽。决明子蛋白经过碱性蛋白酶水解2~6 h，以超滤膜技术产生<3000 u肽组分。UF 2 h（2 h水解产物分离出来的<3000 u组分）表现出最强的ABTS·+清除能力（EC50=229 μg/ mL）和铁螯合能力（EC50=89 μg/mL）。经过热处理和模拟胃肠消化后，UF 2 h的ABTS·+清除能力都得以保留。UF 2 h仅在模拟胃肠消化胃后保留铁螯合活性。试验通过使用固相萃取，凝胶色谱和高效液相色谱对UF 2 h进行分离纯化。通过质谱分析，鉴定了四个肽：PMPVR（599.29 u），FETLPF（752.34 u），KMRDNL（775.37 u）和LDESKRF（893.50 u）。计算机分析预测，在模拟胃肠消化前，四个肽皆无毒无过敏性。胃肠消化后，四个肽释放的片段仍无毒，仅PMPVR和KMRDNL释放的肽片段无过敏性的。UF 2 h及其活性肽可作为抗氧化剂，用于开发功能性食品和营养保健品。

Semen cassiae (SC), seeds of Cassia obtusifolia, is used as treatments for various diseases in Traditional Chinese Medicine. This study evaluated the antioxidant activity and stability of SC hydrolysate fractions and identified peptides in the most active fraction. SC proteins were hydrolyzed by alcalase for 2-6 hours; < 3000 u peptide fractions were produced via membrane ultrafiltration. UF 2 h (fraction produced from 2-hour hydrolysate) exhibited the strongest ABTS·+ scavenging (EC50 = 229 μg/mL) and iron chelating (EC50 = 89 μg/mL) activities. Its ABTS·+ scavenging activity was retained after thermal treatment and simulated gastrointestinal (GI) digestion, but iron chelating activity was fully retained only after GI digestion. Peptides were purified from UF 2 h by using solid phase extraction, gel filtration chromatography and high performance liquid chromatography analysis, guided by ABTS·+ scavenging assay. Four peptides were identified by mass spectrometric analysis: PMPVR (599.29 u), FETLPF (752.34 u), KMRDNL (775.37 u), and LDESKRF (893.50 u). In silico analysis predicted that before simulated GI digestion, all four peptides were non-toxic and non-allergenic. After GI digestion, peptide fragments released from the four peptides were predicted to be still non-toxic, whereas fragments of only PMPVR and KMRDNL were predicted to be non-allergenic. Taken together, UF 2 h and the peptides contained in it are promising antioxidants for the development of functional food and nutraceuticals.