Antihypertensive Effect of Enzyme-Treated Zein in Stroke-Prone Spontaneously Hypertensive Rats

Abstract

Zein was treated by thermolysin and Proleather, the latter a mixture of proteinases from Bacillus sp. The corresponding products were called SD-ZT and DA-Pro, respectively, The hydrolysates resulting from 2 h-hydrolysis by thermolysin and Proleather showed the strongest ACE inhibitory activity, and the IC₅₀ values were 6.5 and 7.5 μg/μl, respectively. Effects of the administration of zein hydrolysates from thermolysin and Proleather on the systolic blood pressures (SBPs) were studied in SHRSP. Intragastric administration of SD-ZT and DA-Pro showed a significant decrease in the SBP at 6 and 24 h. Experimental diets were prepared by mixing 5% (w/w) of SD-ZT or DA-Pro with the control diet and were fed ad libitum to SHRSP for 5 weeks. In comparison with the control group, the elevation of blood pressure of SHRSP fed the SD-ZT diet or DA-Pro diet was suppressed from the 9th day after administration. The serum ACE activities in the DA-Pro group were lower than those in the SD-ZT group and the control group.