Angiotensin converting enzyme (ACE) inhibitory, antihypertensive and antihyperlipidaemic activities of protein hydrolysates from Rhopilema esculentum

► Rhopilema esculentum protein hydrolysate (RPH) showed ACE inhibitory activity. ► RPH could notably reduce the systolic blood pressure after oral administration. ► Meanwhile it also effectively decreased blood lipid in high-fat diet-induced rats. Angiotensin-converting enzyme (ACE) inhibitory, antihypertensive and antihyperlipidaemic activities of protein hydrolysates (RPH) from the jellyfish Rhopilema esculentum were investigated. R. esculentum was hydrolysed sequentially with pepsin and papain, and then the hydrolysate was ultrafiltered with a 2000Da cut-off membrane. It was found that RPH contained high levels of Gly, Glu, Pro, Asp and Ala, having potential ACE inhibitory activity in vitro with an IC50 of 1.28mg/ml. It was also found that systolic blood pressure was reduced markedly in spontaneously hypertensive rats after single and chronic oral administration of RPH, indicating that RPH had an antihypertensive effect. In addition, oral administration of RPH decreased total serum cholesterol and triglyceride, and increased high-density lipoprotein cholesterol in rats fed with high-fat diet. These results indicate that RPH may prove to be a promising functional food for the prevention and treatment of hypertension and hyperlipidaemia.