Angiotensin-converting enzyme inhibitory peptides from Lactobacillus delbrueckii QS306 fermented milk

Angiotensin-converting enzyme inhibitory peptides were isolated and identified from milk fermented using Lactobacillus delbrueckii QS306. The peptide with the highest angiotensin-converting enzyme inhibitory activity (C5) was purified using ultrafiltration with 10 and 3 kDa molecular mass cut-off membranes, Sephadex G-15 (Sigma-Aldrich, St. Louis, MO) gel filtration chromatography, reversed-phase HPLC, and Orbitrap Elite (Thermo Fisher Scientific Inc., Waltham, MA) liquid chromatography-tandem mass spectrometry. We obtained peptide LPYPY by microbial fermentation, which was derived from κ-casein f (AA 77-81). We synthesized LPYPY using an Fmoc solid-phase synthesis method and explored the secondary structure of the pentapeptide. The half maximal inhibitory concentration for the angiotensin-converting enzyme inhibitory activity of LPYPY was 12.87 μg/mL. The results provide additional information for ongoing research and the development of functional foods having antihypertensive effects.

Losartan in the Therapy of Heart Failure Patients

The effects of losartan on myocardial remodeling and neurohumoral status were studied in 240 patients with congestive heart failure. The patients were randomized into 3 groups of 80 subjects. Each group continued to receive conventional therapy including the angiotensin-converting enzyme inhibitor enalapril. Group 1 was also given a placebo, groups 2 and 3 had losartan in doses of 25 mg and 50 mg daily, respectively. The course of treatment was 48 weeks. Cardiac function was assessed by B-mode and Doppler echocardiography. Plasma neurohormone levels were determined by radioimmunoassay. Losartan in a dose of 50 mg daily gave the best improvement in cardiac function and the most marked reduction in plasma levels of renin, angiotensin II, aldosterone, atrial natriuretic peptide, endothelin-1, and norepinephrine levels than the lower dose of losartan or placebo. The fall in cortisol and serotonin levels was similar in each group. These data demonstrate the dose-dependent effects of losartan and clarify its role in the treatment of congestive heart failure.