We evaluated the acute (single-dose) and subacute (repeated-dose) oral toxicity of alcalase-hydrolyzed whey protein concentrate. Our acute study revealed no death or treatment-related complications, and the median lethal dose of whey protein concentrate hydrolysate was >2,500 mg/kg. In the subacute study, when the hydrolysate was fed at 3 different concentrations (200, 400, and 800 mg/kg), no groups showed toxicity changes compared with controls. Then, whey protein concentrate hydrolysate was orally administered to spontaneously hypertensive rats. Results revealed significant reductions in blood pressure in a dose-dependent manner, and dosing at 400 mg/kg led to significant blood pressure reduction (-47.8 mm Hg) compared with controls (blood pressure maintained) and the findings of previous work (-21 mm Hg). Eight peptides-RHPEYAVSVLLR, GGAPPAGRL, GPPLPRL, ELKPTPEGDL, VLSELPEP, DAQSAPLRVY, RDMPIQAF, and LEQVLPRD-were sequentially identified and characterized. Of the peptides, VLSELPEP and LEQVLPRD showed the most prominent in vitro angiotensin-I converting enzyme inhibition with half-maximal inhibitory concentrations of 0.049 and 0.043 mM, respectively. These findings establish strong evidence for the in vitro and in vivo potential of whey protein concentrate hydrolysate to act as a safe, natural functional food ingredient that exerts antihypertensive activity.

中文翻译：

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乳清浓缩蛋白水解物在大鼠模型中的毒性研究和降血压功效，以及多肽表征。

我们评估了alcalase水解乳清蛋白浓缩物的急性（单剂量）和亚急性（重复剂量）口服毒性。我们的急性研究显示没有死亡或与治疗相关的并发症，并且乳清蛋白浓缩物水解​​物的中位致死剂量> 2,500 mg / kg。在亚急性研究中，当以3种不同的浓度（200、400和800 mg / kg）饲喂水解产物时，与对照组相比，没有组显示出毒性变化。然后，将乳清蛋白浓缩物水解​​物口服给予自发性高血压大鼠。结果显示，血压以剂量依赖性方式显着降低，与对照组（维持血压）相比，以400 mg / kg的剂量给药可导致血压显着降低（-47.8 mm Hg）和先前工作的发现（-21）毫米汞柱）。八个肽-RHPEYAVSVLLR，依次确定并表征了GGAPPAGRL，GPPLPRL，ELKPTPEGDL，VLSELPEP，DAQSAPLRVY，RDMPIQAF和LEQVLPRD。在这些肽中，VLSELPEP和LEQVLPRD表现出最显着的体外血管紧张素-I转化酶抑制作用，其半最大抑制浓度分别为0.049和0.043 mM。这些发现为乳清蛋白浓缩物水解​​物作为安全，天然的功能性食品成分发挥了降压活性，在体外和体内潜力方面提供了有力的证据。