Abstract：
BACKGROUND: Hypertension is the most common and chronic severe health problem globally. Corn silk (CS), the silky fibers of corn (Zea mays L.), has a long history of traditional usage as a remedy for edema and hypertension.
OBJECTIVE: The aim of the study was to explore the underlying mechanism by which CS exerts its anti-hypertensive effects and investigate the presence of bioactive molecules in CS aqueous extract.
METHODS: We analyzed the effects of boiling water extract of CS on angiotensin-converting enzyme (ACE) activities, the critical enzyme involved in the regulation of blood pressure. ACE inhibitory peptides from CS extract were identified using proteomics and bioinformatics tools. The binding interfaces between these peptides and ACE were defined by hydrogen-deuterium exchange mass spectrometry (HDX-MS). Subsequently, the anti-hypertensive effects of peptides were further investigated in spontaneously hypertensive rats (SHR).
RESULTS: Our data showed that CS extract exhibited dose-dependent inhibition of ACE activity. Liquid chromatography-tandem mass spectrometry identified a heat-stable peptide bank with 1313 distinct peptide fragments within the CS boiling water extract. Among these, CS-1 (LVPGWTKPICIGR) was selected through PeptideRanker and BIOPEP-UWM analyses. In vitro ACE inhibitory assays confirmed that CS-1 exhibited dose-dependent ACE inhibition, with IC50 values of 10.32 ± 0.41 μmol/L (using HHL as the substrate) and 13.74 ± 1.87 μmol/L (using ZFHL as the substrate). Oral administration of CS-1 led to a significant dose-dependent reduction in blood pressure, with the maximal decrease (42.33 ± 13.08 mmHg) occurring 0.5 h after ingestion. HDX-MS analysis revealed that CS-1 interacted with the zinc-binding motif of ACE, and hydrogen bond interactions were predicted between CS-1 and specific residues, including His361 in the N-domain, as well as His382, Gly386, and His387 in the C-domain of ACE. These findings suggested that the interaction of CS-1 with the residues in the zinc-binding motif of ACE led to ACE activity inhibition and a subsequent decrease in blood pressure in rats.
CONCLUSIONS: A novel heat-stable ACE inhibitory peptide, which interacted with the zinc-binding motif of ACE and reduced blood pressure in SHR, was identified in the CS extract. The presence of ACE inhibitory peptides in the CS extract supports its traditional use in ethnopharmacology for hypertension.
OBJECTIVE: The aim of the study was to explore the underlying mechanism by which CS exerts its anti-hypertensive effects and investigate the presence of bioactive molecules in CS aqueous extract.
METHODS: We analyzed the effects of boiling water extract of CS on angiotensin-converting enzyme (ACE) activities, the critical enzyme involved in the regulation of blood pressure. ACE inhibitory peptides from CS extract were identified using proteomics and bioinformatics tools. The binding interfaces between these peptides and ACE were defined by hydrogen-deuterium exchange mass spectrometry (HDX-MS). Subsequently, the anti-hypertensive effects of peptides were further investigated in spontaneously hypertensive rats (SHR).
RESULTS: Our data showed that CS extract exhibited dose-dependent inhibition of ACE activity. Liquid chromatography-tandem mass spectrometry identified a heat-stable peptide bank with 1313 distinct peptide fragments within the CS boiling water extract. Among these, CS-1 (LVPGWTKPICIGR) was selected through PeptideRanker and BIOPEP-UWM analyses. In vitro ACE inhibitory assays confirmed that CS-1 exhibited dose-dependent ACE inhibition, with IC50 values of 10.32 ± 0.41 μmol/L (using HHL as the substrate) and 13.74 ± 1.87 μmol/L (using ZFHL as the substrate). Oral administration of CS-1 led to a significant dose-dependent reduction in blood pressure, with the maximal decrease (42.33 ± 13.08 mmHg) occurring 0.5 h after ingestion. HDX-MS analysis revealed that CS-1 interacted with the zinc-binding motif of ACE, and hydrogen bond interactions were predicted between CS-1 and specific residues, including His361 in the N-domain, as well as His382, Gly386, and His387 in the C-domain of ACE. These findings suggested that the interaction of CS-1 with the residues in the zinc-binding motif of ACE led to ACE activity inhibition and a subsequent decrease in blood pressure in rats.
CONCLUSIONS: A novel heat-stable ACE inhibitory peptide, which interacted with the zinc-binding motif of ACE and reduced blood pressure in SHR, was identified in the CS extract. The presence of ACE inhibitory peptides in the CS extract supports its traditional use in ethnopharmacology for hypertension.
摘要：
背景：高血压是全球最常见的慢性严重健康问题。玉米丝(CS),玉米(ZeamaysL.)的柔滑纤维，作为治疗水肿和高血压的传统用法历史悠久。
目的：本研究的目的是探索CS发挥其抗高血压作用的潜在机制，并研究CS水提物中生物活性分子的存在。
方法：我们分析了CS沸水提取物对血管紧张素转换酶（ACE）活性的影响，调节血压的关键酶。使用蛋白质组学和生物信息学工具鉴定来自CS提取物的ACE抑制肽。通过氢-氘交换质谱(HDX-MS)确定这些肽与ACE之间的结合界面。随后，在自发性高血压大鼠（SHR）中进一步研究了肽的抗高血压作用。
结果：我们的数据显示CS提取物显示出ACE活性的剂量依赖性抑制。液相色谱-串联质谱法鉴定了CS沸水提取物中具有1313种不同肽片段的热稳定肽库。其中,通过PeptideRanker和BIOPEP-UWM分析选择CS-1(LVPGWTKPICIGR)。体外ACE抑制试验证实CS-1表现出剂量依赖性ACE抑制，IC50值为10.32±0.41μmol/L(使用HHL作为底物)和13.74±1.87μmol/L(使用ZFHL作为底物)。口服CS-1导致血压显著的剂量依赖性降低，摄入后0.5小时发生最大下降（42.33±13.08mmHg）。HDX-MS分析显示CS-1与ACE的锌结合基序相互作用，预测了CS-1与特定残基之间的氢键相互作用，包括N域中的His361，以及ACEC域中的His382、Gly386和His387。这些发现表明CS-1与ACE的锌结合基序中的残基的相互作用导致ACE活性抑制和随后的大鼠血压降低。
结论：一种新型热稳定ACE抑制肽，与ACE的锌结合基序相互作用并降低SHR的血压，在CS提取物中鉴定。CS提取物中ACE抑制肽的存在支持了其在高血压的民族药理学中的传统用途。
目的：本研究的目的是探索CS发挥其抗高血压作用的潜在机制，并研究CS水提物中生物活性分子的存在。
方法：我们分析了CS沸水提取物对血管紧张素转换酶（ACE）活性的影响，调节血压的关键酶。使用蛋白质组学和生物信息学工具鉴定来自CS提取物的ACE抑制肽。通过氢-氘交换质谱(HDX-MS)确定这些肽与ACE之间的结合界面。随后，在自发性高血压大鼠（SHR）中进一步研究了肽的抗高血压作用。
结果：我们的数据显示CS提取物显示出ACE活性的剂量依赖性抑制。液相色谱-串联质谱法鉴定了CS沸水提取物中具有1313种不同肽片段的热稳定肽库。其中,通过PeptideRanker和BIOPEP-UWM分析选择CS-1(LVPGWTKPICIGR)。体外ACE抑制试验证实CS-1表现出剂量依赖性ACE抑制，IC50值为10.32±0.41μmol/L(使用HHL作为底物)和13.74±1.87μmol/L(使用ZFHL作为底物)。口服CS-1导致血压显著的剂量依赖性降低，摄入后0.5小时发生最大下降（42.33±13.08mmHg）。HDX-MS分析显示CS-1与ACE的锌结合基序相互作用，预测了CS-1与特定残基之间的氢键相互作用，包括N域中的His361，以及ACEC域中的His382、Gly386和His387。这些发现表明CS-1与ACE的锌结合基序中的残基的相互作用导致ACE活性抑制和随后的大鼠血压降低。
结论：一种新型热稳定ACE抑制肽，与ACE的锌结合基序相互作用并降低SHR的血压，在CS提取物中鉴定。CS提取物中ACE抑制肽的存在支持了其在高血压的民族药理学中的传统用途。
