Health Care R&D, Sunstar Group, Takatsuki, Osaka, Japan.
Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji, Kyoto, Japan.
Mol Nutr Food Res. 2018 Feb;62(4). doi: 10.1002/mnfr.201700732. Epub 2018 Jan 25.
Hypertension is a risk factor for arteriosclerosis. In this study, we investigate the antihypertensive effect of protease-digested rice bran in a spontaneously hypertension rat (SHR) model. We also purify a novel antihypertensive peptide from the digest.
Thermolysin-digested rice bran (TRB) is administered to SHRs for 4 weeks, and systolic blood pressure (SBP) was measured weekly using the tail-cuff method. TRB shows an antihypertensive effect in a dose-dependent manner. TRB also reduces angiotensin I-converting enzyme (ACE) activity in lung tissue and serum troponin I levels. TRB is fractionated by HPLC and ACE-inhibitory activity in the HPLC fractions is measured. Peptides LRA and YY are identified from the two fractions with the strongest ACE-inhibitory activity. Amino acid sequence of these peptides are found in a vicilin-like seed storage protein, and identified in rice bran protein using the peptide mass fingerprint method. We confirm that LRA and YY are cleaved by thermolysin digestion of a model synthetic peptide. Orally administered LRA (0.25 mg kg ) or YY (0.5 mg kg ) lowers the SBP of SHRs at 4 h after administration.
We identify a novel, orally active antihypertensive peptide, LRA from the digest of rice bran protein.
高血压是动脉硬化的一个危险因素。在这项研究中，我们在自发性高血压大鼠（SHR）模型中研究了蛋白酶消化米糠的降压作用。我们还从消化产物中纯化了一种新型的降压肽。
用糜蛋白酶消化米糠（TRB）给 SHR 喂食 4 周，每周用尾套法测量收缩压（SBP）。TRB 呈剂量依赖性降压作用。TRB 还降低肺组织中的血管紧张素 I 转换酶（ACE）活性和血清肌钙蛋白 I 水平。TRB 通过 HPLC 进行分级，并用 HPLC 级分中的 ACE 抑制活性进行测量。从 ACE 抑制活性最强的两个级分中鉴定出肽 LRA 和 YY。这些肽的氨基酸序列存在于类菜豆球蛋白种子贮藏蛋白中，并使用肽质量指纹图谱法在米糠蛋白中鉴定。我们证实 LRA 和 YY 是通过糜蛋白酶消化模型合成肽切割而来。口服给予 LRA（0.25mg/kg）或 YY（0.5mg/kg）可在给药后 4 小时降低 SHR 的 SBP。
我们从米糠蛋白的消化产物中鉴定出一种新型的、具有口服活性的降压肽 LRA。
