Study Of Purification And Antihypertensive Ability Of Peptides Extracted From Jinhua Ham

Jinhua dry-cured ham is a kind of famous Chinese traditional meat product.The ripening period of Jinhua ham is at least 6 months.Proteins in the ham are largely hydrolyzed by endogenous enzymes during this period.A large number of free amino acids and peptides are generated due to the intense hydrolysis.Generated components can contribute to the unique flavor formation of Jinhua ham.Abundant peptides may also have some biological activities including antihypertensive and antioxidant.Nowadays,hypertension is a major chronic disease in the world.There is no effective cure for medical treatment to date.Continuous administration of antihypertensive drugs is the only way to control the blood pressure of patients once they are diagnosed with hypertension.However,the antihypertensive drugs,such as captopril,could have some side effects.Compared with these drugs,some antihypertensive peptides generated from food,which has been widely concerned,could get the same effect with a safer way.In this study,the antihypertensive ability of crude peptides in vitro and in vivo extracted from Jinhua ham was tested.The peptides extracted from Jinhua ham were submitted to different processing conditions and a simulated gastro-intestinal digestion and their stability was studied.Furthermore,size-exclusion chromatography and ion exchange chromatography were used to separate the antihypertensive peptides extracted from Jinhua ham.The separated fraction was then identified by Nano-LC-ESI-MS/MS.The specific research contents and results are shown as follows:1.Antihypertensive activity of peptides extracted from Jinhua hamIn this study,the antihypertensive activity of peptides in vitro and in vivo extracted from Jinhua ham was tested.The antihypertensive activity in vitro was evaluated by the angiotensin converting enzyme(ACE)inhibitory activity and the renin inhibitory activity.The results showed that the half maximal inhibitory concentration(IC50)of peptides on ACE was 8.16 mg/mL,and the IC50 of peptides on renin was 6.69 mg/mL.Peptides with a high peptide concentration(20 mg/mL)had the ability to reduce heart rate,systolic and diastolic blood pressure in spontaneously hypertensive rats(SHR),which was similar to 5 mg/mL of captopril.High concentration peptides exerted effect later than captopril,while its efficacy was sustainable for longer durations.2.Stability of antihypertensive peptides extracted from Jinhua dry-cured hamThe ACE-inhibitory activity was measured after the treatments of heat,NaCl,pH and simulated gastro-intestinal digestion.Peptides showed a good stability against different heating temperatures(up to 100 ?),heating times(up to 60 min)and acid conditions.The NaCl had no significant effects on the ACE-inhibitory activity,while there was a sharp decline under alkaline condition.The ACE-inhibitory activity increased by 4.01%after pepsin treatment and then remained constant after trypsin treatment.The increased ACE-inhibitory activity after pepsin digestion could be explained by the greater exposure of hydrophobic residues.In this study,peptides extracted from Jinhua ham were proved to have ACE-inhibitory activity which showed a good stability against various processing conditions as well as the simulated gastro-intestinal digestion.3.Purification and identification of antihypertensive peptides extracted from Jinhua hamThe crude peptide extracts of Jinhua ham were separated and purified by affinity chromatography,size exclusion chromatography and ion exchange chromatography to obtain the active components.The Nano-LC-ESI-MS/MS was used to determine the amino acid sequence of the potentially active peptide in the isolated component.The sequences of the main antihypertensive peptides with strong ACE inhibitory activity was determined as DEP,NLLPP and DAVLPA according to the structure and comparison of peptides sequences.