Antihypertensive Properties on Spontaneously Hypertensive Rats of Peptide Hydrolysates from Silkworm Pupae Protein

Peptide hydrolysates of silkworm pupae protein with molecular weight of less than 5000 Da were prepared by ultrafiltration. The extracted peptide hydrolysates of silkworm pupae protein had inhibitory action on angiotensin-I-converting enzyme activity in vitro. The hydrolysates were orally administered to spontaneously hypertensive rats (SHR) in one period and long-term (four weeks). The results showed that the systolic blood pressure (SBP) of the treatment groups decreased in a dose-related manner. After one oral administration of silkworm protein hydrolysates with doses of 60, 20 and 5 mg/kg, the SBP of SHR decreased by 21.5, 13.8, and 9.0 mmHg in 1.5 h. After four weeks of the treatment in 80 mg/kg, the SBP decreased by 25 mmHg, with the antihypertensive activity close to 4 mg/kg of captopril;the SBP of the 40 mg/kg dose group also decreased by 17.5 mmHg. The peptide hydrolysate did not affect the SBP in normal, non-hypertensive rats in one period and long-term treatments. The acute toxicity research showed that the peptide hydrolysates were safe and without side effects. This research would be helpful in exploring the silkworm protein peptides as functional components for the antihypertension treatment.

Purification and Molecular Docking Study of Angiotensin-I Converting Enzyme (ACE) Inhibitory Peptide from Alcalase Hydrolysate of Hazelnut (<i>Corylus heterophylla</i>Fisch) Protein

Although a number of bioactive peptides are capable of angiotensin I-converting enzyme (ACE) inhibitory effects, little is known regarding the mechanism of hazelnut peptides using molecular simulation. In the present study, gel filtration chromatography, reverse phase-high performance liquid chromatography, and liquid chromatography-electrospray ionization-tandem mass (LC-ESI-MS/MS) were employed for purifying and identifying the ACE inhibitory peptides from hazelnut. To understand the mode of action of these peptides, the interaction between the inhibitory peptides and ACE was investigated. The results identified novel ACE inhibitory peptides Asp-Asp-Glu-Leu-Arg-Gln-Ala (DDELRQA), Asp-Asp-Glu-Leu-Arg-Ala-Ala (DDELRAA), and Asp-Gly-Glu-Leu-Arg-Glu (DGELRE). The binding free energies of DDELRQA, DDELRAA, and DGELRE for ACE were -10.2, -9.0, and -8.8 kcal/mol, respectively. This study proves the high stability of ACE inhibitory peptides derived from hazelnut against different temperature and pH of processing.

Dual antidiabetic and antihypertensive activity of fucoxanthin isolated from Sargassum wightii Greville in in vivo rat model

In a previous study from our laboratory, fucoxanthin purified from brown algae, Sargassum wightii Greville has found to exhibit antioxidant activity and inhibition of angiotensin-I-converting enzyme(ACE)in vitro. The present study aims in understanding the protective effect of fucoxanthin purified from S. wightii against diabetes with hypertension in in vivo. Diabetes and hypertension were induced in rat by streptozotocin and sodium chloride treatment, respectively. In diabetes with hypertension rat, the blood pressure was increased along with hyperglycemia. Administration of fucoxanthin significantly reduced the blood pressure and ACE activity in diabetes with hypertension rat. Furthermore, administration of fucoxanthin significantly reduced the hyperglycemic state. The activity of various enzymes in the liver(hexokinase, glucose-6-phosphate dehydrogenase, glucose-6-phosphatase and fructose-1,6-phosphatase)and serum(creatine kinase)were normalized to that of control level. The level of glycogen, glycoprotein component and lipid profile were equivalent to control level by fucoxanthin administration in diabetes with hypertension rats. Fucoxanthin ameliorated the oxidative stress by preserving the endogenous antioxidant levels in diabetes with hypertension rats. Also, the pancreatic histological integrity was similar to that of control level in diabetes with hypertension rats by fucoxanthin treatment. Altogether, fucoxanthin showed dual antidiabetic and antihypertensive activity in vivo.

Bioactivity of non-extractable phenolics from lemon peel obtained by enzyme and ultrasound assisted extractions

Lemon peel waste constitutes a natural resource for bioactive phenolics with antioxidant,antihypertensive and antidiabetic activities.Bioactivities of non-extractable phenolics from lemon peel obtained by conventional heat-,enzyme-,ultrasound-,and ultrasound-enzyme-assisted extractions were evaluated in comparison with those of extractable phenolics.The antioxidant,angiotensin-I-converting enzyme(ACE),andα-amylase inhibitory activities and phenolic profile of the phenolic fractions were analysed.While the extractable fraction had higher total phenolic content,ascorbic acid content,and antioxidant activity,phenolic profile analysis indicated that the non-extractable fraction contained higher concentrations of phenolics especially hesperidin and hesperetin.The concentrations of hesperidin and hesperetin in the non-extractable fraction were 270.9 mg/100 g dry weight and 415.9 mg/100 g dry weight,respectively,which were about two-fold higher than those present in the extractable fraction.Moreover,ACE andα-amylase inhibitory activities of non-extractable fraction were stronger than those of the extractable fraction.Total phenolic content,total flavonoid content,and antioxidant activity were increased by enzyme and ultrasound treatments compared to those by conventional heat treatment.However,ACE inhibitory activities of all non-extractable fractions were similar whileα-amylase inhibitory activity was higher in ultrasound-and ultrasound-enzyme-treated fractions.While ultrasound-assisted extraction slightly improved the yield of non-extractable phenolics,enzyme-assisted extraction yielded two-to four-fold increases in the amounts of phenolic compounds compared to heat-assisted extraction.Non-extractable phenolic fraction from lemon peel was found to have a significant potential as an antihypertensive and antidiabetic agent.

Vercytochalasins A and B: Two unprecedented biosynthetically related cytochalasins from the deep-sea-sourced endozoic fungus Curvularia verruculosa

Vercytochalasins A(1) and B(2), two biosynthetically related cytochalasins featuring novel structure and substituents, were isolated from the endozoic fungus Curvularia verruculosa which was associated with the deep-sea squat lobster Shinkaia crosnieri collected from the cold seep environment in South China sea. Their structures were elucidated by detailed interpretation of NMR spectroscopic and mass spectrometric data. The absolute configurations were confirmed by NOESY experiments as well as by DP4+ and ECD calculations. Differed from common cytochalasins, compound 1 is an uncommon secocytochalasin featuring the ester group cleaved between C-9 and C-23, and incorporating an additional oxygenated C4 unit which coupled with C-20 and C-22 to form a new substituted cyclohexenone moiety, while compound 2 contains an unusual 2–hydroxy-3-oxobutan-2-yl unit at C-22. Both compounds are distinctive from the commonly described cytochalasins. Compound 1 exhibited potent activity against angiotensinI-converting enzyme(ACE) whereas compound 2 showed antibacterial activity. Molecular docking simulations were performed to explore the intermolecular interaction of compounds 1 and 2 with ACE.