酒糟是酿酒过程中的副产物之一，富含多种天然活性物质。该研究以米酒糟为原料，通过水提得到粗提物的ACE抑制率为42.93%，与同次测得市售降压肽ACE抑制率64.52%相差21.25%。随后在乙醇体积分数90%处理，上清经陶瓷膜和纳滤膜过滤后用石油醚萃取，萃取后的样品再先后通过3、0.2 μm和5 000 u超滤膜分离。最终5 000 u透过液的ACE抑制率46.00%高于同次测得市售降压肽39.57%，超出了6.43%。最后通过LTQ Orbitrap Velos Pro对可能存在的活性肽段进行解析，辅以Compound Discovery软件鉴定出Val-Val-Val、Ile-Ser-Val、Val-Pro-Leu、Leu-Ser-Glu、Phe-Tyr、Val-Arg等11条活性短肽，不少肽段具有Val、Phe、Tyr等已被证实与ACE抑制机制有关的疏水氨基酸或芳香族氨基酸。实验表明上述分离手段能提高多肽混合物的ACE抑制效果。从米酒糟中分离出具有高ACE抑制活性的多肽混合物为酒糟的加工利用提供了理论依据。

Distiller' grains are one of the by-products of the winemaking process, and rich in a variety of natural active substances. In this research, the ACE inhibition rate of the crude extract obtained by water extraction from the rice distiller's grains was 42.93%, which was 21.25% lower than that (64.52%) of the commercially available antihypertensive peptide (measured at the same time). Subsequently, the crude extracted was treated with the ethanol (90% volume fraction). Then, the resulting supernatant was filtered by ceramic membrane and nanofiltration membrane, then extracted with petroleum ether. The extracted samples were separated by 3, 0.2 μm and 5 000 u ultrafiltration membranes. The ACE inhibition rate of the 5 000 u permeate was 46.00%, which was higher than that (39.57%) of the commercially available antihypertensive peptide (difference: 6.43%). Finally, LTQ Orbitrap Velos Pro was used, with the aid of Compound Discovery software, to analyze the possible bioactive peptides. Eleven active short peptides were identified, including Val-Val-Val, Ile-Ser-Val, Val-Pro-Leu, Leu-Ser-Glu, Ph-Tyr, and Val-Arg. These peptides contained hydrophobic or aromatic amino acids that have been shown to be involved in ACE inhibition mechanism, such as Val, Phe and Tyr. The experimental results showed that the above separation methods could improve the ACE inhibition effect of the polypeptide mixture. The separation of polypeptide mixtures with high ACE inhibition activities from distiller' grains provides a theoretical basis for the processing and utilization of distiller's grains.

国家自然科学基金项目（31972078）；广东省现代农业产业共性关键技术研发创新团队建设项目（2023KJ117）；阳江市“揭榜挂帅”项目（SDZX2023002）