ACE-inhibitory and antihypertensive properties of a bovine casein hydrolysate

The aim of this study was to investigate the potential angiotensin converting enzyme (ACE)-inhibitory activity and the antihypertensive effect, after a single oral administration, of a pepsin hydrolysed bovine casein (HBC) and a fraction with molecular mass lower than 3000 Da (HBC < 3000). ACE-inhibitory activity was measured by spectrophotometric assay. These products were orally administered by gastric intubation. The systolic (SBP) and the diastolic blood pressure (DBP) were measured in spontaneously hypertensive rats by the tail cuff method before administration and also 2, 4, 6, 8, and 24 h post-administration. HBC showed a potent ACE-inhibitory activity. This activity was 10 times higher in HBC < 3000. HBC and HBC < 3000 decreased the arterial blood pressure of the rats. The decrease in the SBP observed for HBC (400 mg/kg) or HBC < 3000 (200 mg/kg) was less pronounced than that caused by 50 mg/kg of captopril (antihypertensive positive control). However, the maximal decreases in DBP caused by HBC or HBC < 3000 were as high as the maximum decrease observed for captopril. The antihypertensive effect of these products was transient and reverted 24 h after the administration. HBC and HBC < 3000 exert antihypertensive effect caused by small peptides with ACE-inhibitory activity.     

Angiotensin-converting enzyme inhibitory activity of Lactobacillus helveticus strains from traditional fermented dairy foods and antihypertensive effect of fermented milk of strain H9

Hypertension is a major global health issue which elevates the risk of a large world population to chronic life-threatening diseases. The inhibition of angiotensin-converting enzyme (ACE) is an effective target to manage essential hypertension. In this study, the fermentation properties (titratable acidity, free amino nitrogen, and fermentation time) and ACE-inhibitory (ACEI) activity of fermented milks produced by 259 Lactobacillus helveticus strains previously isolated from traditional Chinese and Mongolian fermented foods were determined. Among them, 37 strains had an ACEI activity of over 50%. The concentrations of the antihypertensive peptides, Ile-Pro-Pro and Val-Pro-Pro, were further determined by ultra performance liquid chromatography with quadrupole-time-of-flight mass spectrometry. The change of ACEI activity of the fermented milks of 3 strains exhibiting the highest ACEI activity upon gastrointestinal protease treatment was assayed. Fermented milks produced by strain H9 (IMAU60208) had the highest in vitro ACEI activity (86.4 ± 1.5%), relatively short fermentation time (7.5 h), and detectable Val-Pro-Pro (2.409 ± 0.229 µM) and Ile-Pro-Pro (1.612 ± 0.114 µM) concentrations. Compared with the control, a single oral dose of H9-fermented milk significantly attenuated the systolic, diastolic, and mean blood pressure of spontaneously hypertensive rats (SHR) by 15 to 18 mmHg during the 6 to 12 h after treatment. The long-term daily H9-fermented milk intake over 7 wk exerted significant antihypertensive effect to SHR, but not normotensive rats, and the systolic and diastolic blood pressure were significantly lower, by 12 and 10 mmHg, respectively, compared with the control receiving saline. The feeding of H9-fermented milk to SHR resulted in a significantly higher weight gain at wk 7 compared with groups receiving saline, commercial yogurt, and captopril. Our study identified a novel probiotic L. helveticus strain originated from kurut sampled from Tibet (China), which is a valuable resource for future development of functional foods for hypertension management.     

Antihypertensive activity of milk fermented by Enterococcus faecalis strains isolated from raw milk

A total of 231 microorganisms were isolated from raw cow milk samples and the angiotensin-converting enzyme-inhibitory (ACEI) activity of the resultant fermented milk produced with the isolated microorganisms was assayed. Forty-six of these microorganisms were selected on the basis of high ACEI activity. Four Enterococcus faecalis strains stood out as producers of fermented milk with potent ACEI activity (IC₅₀ (the protein concentration that inhibits 50% of ACE activity): 34–59 μg mL⁻¹). Single doses (5 mL kg⁻¹) of the whey fraction obtained from these fermented milk samples were administered to spontaneously hypertensive rats (SHR) and to normotensive Wistar-Kyoto (WKY) rats in order to investigate their possible antihypertensive activity. Highly significant decreases in the systolic blood pressure (SBP) and in the diastolic blood pressure (DBP) were observed when the fermented milk was administered to SHR. Nevertheless, the fermented milk did not modify the SBP and the DBP of the WKY rats. Raw cow milk is an excellent source of wild lactic acid bacteria able to produce fermented milk with antihypertensive activity and antihypertensive activity of milk fermented by Enterococcus faecalis strains was associated with peptides different from Ile-Pro-Pro and Val-Pro-Pro.     

Antihypertensive effect of corn peptides,produced by a continuous production in enzymatic membrane reactor,in spontaneously hypertensive rats

The aim of this study was to produce corn peptides (CP) with potent angiotensin converting enzyme (ACE)-inhibitory activity and to investigate antihypertensive effects in spontaneously hypertensive rats (SHRs). Results showed that the hydrolysate yield and quality were stable during continuous CP production using an enzymatic membrane reactor (EMR). The hydrolysate was then filtered through a 3 kDa cut-off membrane and the IC₅₀ value of permeate was decreased fourfold (IC₅₀ = 0.29 mg protein/ml). Gastric-intubation CP (M_w < 3 kDa) at a dose of 100 mg/kg bw revealed the best antihypertensive effects in both acute and long-term animal studies using SHRs’ models, the reductions in maximal systolic blood pressure (SBP) were 26.57 mm Hg and 34.45 mm Hg, respectively. Long-term antihypertensive effect of CP administration at a dose of 100 mg/kg bw was comparable to Captopril at 2 mg/kg bw dose. The CP significantly inhibited the ACE activities in SHRs’ lungs and testes (p < 0.01 ∼ p < 0.05) suggesting that these were CP’s target sites.     

Determination of stilbenes in Sicilian pistachio by high-performance liquid chromatographic diode array (HPLC-DAD/FLD) and evaluation of eventually mycotoxin contamination

In this work, we have investigated about the presence of several natural stilbenes in 12 samples of pistachios harvested from 10 different farms of Sicily (Bronte and Agrigento). At the same time, we have evaluated the relation between the stilbenes synthesis and the possible contamination of mycotoxin produced by Aspergillus flavus and Aspergillus parasiticus. We have found two types of stilbenes in the samples of pistachios examined: trans-resveratrol and trans-resveratrol-3-O-β-glucoside (trans-piceid). Their concentration ranged from 0.07 to 0.18 mg/kg (av. = 0.12 ± 0.03 mg/kg) for trans-resveratrol, from 6.20 to 8.15 mg/kg (av. = 6.97 ± 0.55 mg/kg) for trans-piceid and from 6.38 to 8.27 mg/kg (av. = 7.09 ± 0.54 mg/kg) for total resveratrol.     

Red mold dioscorea decreases blood pressure when administered alone or with amlodipine and is a potentially safe functional food in SHR and WKY rats

Hypertension is a risk factor for metabolic syndromes and cardiovascular diseases. Statins are antihypertensive, but can cause rhabdomyolysis as a side effect, which involves the breakdown of muscle fibres and release of myoglobin into the bloodstream. In this study, we used hypertensive rats to investigate whether the interaction between Monascus-fermented products (red mold dioscorea; RMD) and amlodipine increases the risk of rhabdomyolysis and toxicity. A single oral dose of RMD (176 mg/kg) significantly decreased systolic blood pressure (SBP) and diastolic blood pressure (DBP). Moreover, administration of RMD, alone or in combination with amlodipine, did not cause significant rhabdomyolysis and did not impair the metabolic or physiological functions of the liver or kidney. RMD treatment had hypocholesterolemic and hypotriacylglycerolemic effects, indicating that RMD may prevent the incidence of atherosclerosis. The findings of this study lend support to the potential use of RMD as a novel therapeutic and antihypertensive functional food.     

Potentials to differentiate milk composition by different feeding strategies

To investigate the effect of the dietary intake of the cow on milk composition, bulk-tank milk was collected on 5 occasions from conventional (n = 15) and organic (n = 10) farms in Denmark and on 4 occasions from low-input nonorganic farms in the United Kingdom, along with management and production parameters. Production of milk based on feeding a high intake of cereals, pasture, and grass silage resulted in milk with a high concentration of α-linolenic acid (9.4 ± 0.2 mg/kg of fatty acids), polyunsaturated fatty acids (3.66 ± 0.07 mg/kg of fatty acids), and natural stereoisomer of α-tocopherol (RRR-α-tocopherol, 18.6 ± 0.5 mg/kg of milk fat). A milk production system using a high proportion of maize silage, by-products, and commercial concentrate mix was associated with milk with high concentrations of linoleic acid (LA; 19.7 ± 0.4 g/kg of fatty acids), monounsaturated fatty acids (27.5 ± 0.3 mg/kg of fatty acids), and a high ratio between LA and α-linolenic acid (4.7 ± 0.2). Comparing these 2 production systems with a very extensive nonorganic milk production system relying on pasture as almost the sole feed (95 ± 4% dry matter intake), it was found that the concentrations of conjugated LA (cis-9,trans-11; 17.5 ± 0.7 g/kg of fatty acids), trans-11-vaccenic acid (37 ± 2 g/kg of fatty acids), and monounsaturated fatty acids (30.4 ± 0.6 g/kg of fatty acids) were higher in the extensively produced milk together with the concentration of antioxidants; total α-tocopherol (32.0 ± 0.8 mg/kg of milk fat), RRR-α-tocopherol (30.2 ± 0.8 mg/kg of milk fat), and β-carotene (9.3 ± 0.5 mg/kg of milk fat) compared with the organic and conventional milk. Moreover, the concentration of LA (9.2 ± 0.7 g/kg of fatty acids) in milk from the extensive milk production system was found to approach the recommended unity ratio between n-6 and n-3, although extensive milk production also resulted in a lower daily milk yield.     

Dietary fiber,amino acid,fatty acid and tocopherol contents of the edible seaweeds Ulva lactuca and Durvillaea antarctica

The nutritional composition of the edible seaweeds Durvillaea antarctica (frond and stem) and dried Ulva lactuca was determined, including the soluble (SDF), insoluble (IDF) and total (TDF) dietary fiber content, amino acid and fatty acid profiles along with tocopherols and tocotrienols (pro-vitamin E). Results show that U. lactuca contained 60.5 ± 1.5%, and D. antarctica frond and stem 71.4 ± 1.5% and 56.4 ± 0.4% of TDF, respectively. Levels for the different amino acids ranged from 0.7 ± 0.1 to 1508.4 ± 9.5 (mg/100 g protein) in U. lactuca, from 0.2 ± 0.0 to 2019.9 ± 5.2 (mg/100 g protein) in D. antarctica (stem), and from 0.3 ± 0.0 to 1052.6 ± 2.9 (mg/100 g protein) in D. antarctica (leaves). In the three seaweeds, the most abundant fatty acid was C18:1ω9cis which in U. lactuca accounted for 27.42 ± 2.60%; in D. antarctica it was 25.36 ± 3.10% and 25.83 ± 2.52% in leaves and stem, respectively. In D. antarctica, γ-tocotrienol (651.7 ± 5.1 mg/kg), δ-tocopherol (245.9 ± 3.7 mg/kg) and α-tocopherol (179.4 ± 12.1 mg/kg) were determined in fronds, α-tocopherol (258.0 ± 7.2 mg/kg) was determined in stem. U. lactuca, showed a high γ-tocopherol level (963.5 ± 3.8 mg/kg).     

Solid phase extraction in the analysis of squalene and tocopherols in olive oil

Solid phase extraction (SPE) is only marginally employed in the official EU methods on the characteristics of olive oil. In the present study a SPE procedure was optimised for the subsequent extraction of squalene and α-tocopherol prior to HPLC of triacylglycerols. Squalene elution from a silica cartridge was achieved with 10 ml of n-hexane whereas α-tocopherol was isolated using 2 × 10 ml n-hexane/diethylether, 99:1, v/v. For both constituents, the precision of the SPE procedure (squalene: CV % = 4.4–6.4, n = 5; α-tocopherol: CV% = 5.3, n = 7) and the mean recovery (squalene: 88 ± 9% and 85 ± 4% for 700 and 4000 mg/kg levels of addition; α-tocopherol: 88 ± 6% and 91 ± 3% for 70 and 225 mg/kg levels of addition, respectively) were satisfactory with regards to those reported using other HPLC procedures with or without sample pretreatment. The results of the present study can be proved useful in the official control of virgin olive oil.     

Pilot-scale production of low molecular weight peptides from corn wet milling byproducts and the antihypertensive effects in vivo and in vitro

A pilot-scale production was developed to enhance the value of proteins from corn gluten meal (CGM). Corn protein isolate (CPI) with high protein content (90.68%) was obtained through heat treatment of CGM (150 kg) in aqueous alkaline solution. Two-step enzymatic hydrolysis and multistage separation were applied to enrich corn oligopeptides (COP) with low molecular weights, 96.77% of which were less than 1000 Da. The greatest antihypertensive effect of COP treatment in spontaneously hypertensive rats (SHR) was observed at a dose of 0.45 g/kg. One major ACE-inhibitory peptide, Ala-Tyr, was identified and quantified (9.16 ± 0.08 mg/g) from COP. The ACE inhibitory activity of Ala-Tyr (IC₅₀ = 0.037 mg/ml) was over 27 times higher than that of COP (IC₅₀ = 1.020 mg/ml). The results indicate that COP may be a source of natural antihypertensive compounds that could be used for drugs or functional food ingredients.