In Vitro And In Vivo Antihypertensive Effects Of Sweet Potato Peptides By Enzymatic Hydrolysis Under High Hydrostatic Pressure

The sweet potato products processing and starch industries produce a high amount of waste that contains highly nutritious components including protein,vitamins and minerals,etc.Sweet potato protein?SPP?is of high nutritional value and possesses antioxidant,anticancer,antihypertensive,and many other reported bioactive potentials,which can be a good source of bioactive peptides.In this study,effects of high hydrostatic pressure?HHP?on angiotensin I-converting enzymes?ACE?inhibitory activity sweet potato protein hydrolysates?SPPH?prepared by Papain,Pepsin and Alcalase were investigated.In addition,in vivo antihypertensive effects of the produced peptides with high ACE inhibitory activity were investigated by feeding the spontaneously hypertensive rats?SHRs?.SPPH with ACE inhibitory activity was prepared by Papain,Pepsin and Alcalase under HHP?100,200 and 300 MPa?.HHP significantly increased degree of hydrolysis?DH?,nitrogen recovery?NR?and molecular weight?MW?<3 kDa fractions contents of SPPH by all three enzymes?P<0.05?.MW<3 kDa peptides fractions from SPPH by Alcalase under 100 MPa showed the highest ACE inhibitory activity(IC₅₀ value 32.24?g/ml),and was subjected to purification and identification by semi-preparative RP-HPLC and LC-MS/MS.Five identified peptides with sequences of VSAIW,AIWGA,FVIKP,VVMPSTF and FHDPMLR displayed good ACE inhibitory activity with the contribution of Val,Trp,Phe and Arg.In vivo antihypertensive effects of SPPH prepared by Alcalase under 100 MPa,Papain under 200MPa and Pepsin under 300 MPa were investigated.SBP of SHPs with SPPH by Alcalase at 200 and 100mg/kg body weight doses?bd?were decreased to 181.5 and 186.9 mmHg compared to blank control?202.0 mmHg?.SBP of SHPs with SPPH by Pepsin at 200 and 100 mg/kg body weight doses were decreased to 185.7 and 189.0 mmHg,while those with SPPH by Papain were decreased to 192.6 and193.7 mmHg respectively.Comparatively,significant decreases in diastolic blood pressure?DBP?were also observed for SHRs with SPPH by Alcalase and Pepsin at 200 and 100 mg/kg body weight doses.Hypolipidimic and antioxidant effects of SPPH prepared by Alcalase under 100 MPa,Papain 200MPa and Pepsin under 300 MPa on SHRs were investigated.Compared to the blank control?0.73 mM/L?,serum triglycerides of SHRs with SPPH by Alcalase,Pepsin and Papain at a 200 mg/kg body weight dose were significantly decreased,which were 0.55,0.54 and 0.56 mM/L respectively.Super oxide dismutase?SOD?activities were found increased in serum of SHRs with SPPH by Alcalase and Pepsin at 200 mg/kg body weight doses?8.96 and 8.49 u/L?when compared to the blank control?8.01 u/L?.In addition,histopathological studies of kidneys and heart showed no notable pathological changes in samples'groups as compared to blank group.Thus,in vivo antihypertensive effects of SPPH not only depended on its ACE inhibitory activity,but also with the contribution of antioxidant level in rats.Taken together,SPPH prepared by proper enzymatic hydrolysis under HHP showed both in vitro and in vivo antihypertensive effects,which could be potentially used in healthy food.