Ultrafast Reaction of the Drug Hydralazine with Apurinic/Apyrimidinic Sites in DNA Gives Rise to a Stable Triazolo[3,4-a]phthalazine Adduct.

The clinically used antihypertensive agent hydralazine rapidly generates hydrazone-derived adducts by reaction with apurinic/apyrimidinic (also known as abasic or AP) sites in many different sequences of duplex DNA. The reaction rates are comparable to those of some AP-trapping reagents previously described as "ultrafast." Initially, reversible formation of a hydrazone adduct is followed by an oxidative cyclization reaction that generates a chemically stable triazolo[3,4-a]phthalazine adduct. The net result is that the reaction of hydralazine with AP sites in duplex DNA yields a rapid and irreversible adduct formation. Although the hydrazone and triazolo[3,4-a]phthalazine adducts differ by only two mass units, it was possible to use MALDI-TOF-MS and ESI-QTOF-nanospray-MS to quantitatively characterize mixtures of these adducts by deconvolution of overlapping isotope envelopes. Reactions of hydralazine with the endogenous ketone pyruvate do not prevent the formation of the hydralazine-AP adducts, providing further evidence that these adducts have the potential to form in cellular DNA. AP sites are ubiquitous in cellular DNA, and rapid, irreversible adduct formation by hydralazine could be relevant to the pathogenesis of systemic drug-induced lupus erythematosus experienced by some patients. Finally, hydralazine might be developed as a probe for the detection of AP sites, the study of cellular BER, and marking the location of AP sites in DNA-sequencing analyses.

New Perspectives for Antihypertensive Sartans as Components of Co-crystals and Co-amorphous Solids with Improved Properties and Multipurpose Activity.

Sartans (angiotensin II receptor blockers, ARBs), drugs used in the treatment of hypertension, play a principal role in addressing the global health challenge of hypertension. In the past three years, their potential use has expanded to include the possibility of their application in the treatment of COVID-19 and neurodegenerative diseases (80 clinical studies worldwide). However, their therapeutic efficacy is limited by their poor solubility and bioavailability, prompting the need for innovative approaches to improve their pharmaceutical properties. This review discusses methods of co-crystallization and co-amorphization of sartans with nonpolymeric, low molecular, and stabilizing co-formers, as a promising strategy to synthesize new multipurpose drugs with enhanced pharmaceutical properties. The solid-state forms have demonstrated the potential to address the poor solubility limitations of conventional sartan formulations and offer new opportunities to develop dual-active drugs with broader therapeutic applications. The review includes an in-depth analysis of the co-crystal and co-amorphous forms of sartans, including their properties, possible applications, and the impact of synthetic methods on their pharmacokinetic properties. By shedding light on the solid forms of sartans, this article provides valuable insights into their potential as improved drug formulations. Moreover, this review may serve as a valuable resource for designing similar solid forms of sartans and other drugs, fostering further advances in pharmaceutical research and drug development.

Synthesis, biosimulation and pharmacological evaluation of benzimidazole derivatives with antihypertensive multitarget effect.

In this study, we synthesized a series of seven benzimidazole derivatives incorporating the structural acidic framework of angiotensin II (Ang II) type 1 receptor (AT1R) antagonists (ARA-II) employing a three-step reaction sequence. The chemical structures were confirmed by 1H NMR, 13C NMR and mass spectral data. Through biosimulation, compounds 1-7 were identified as computational safe hits, thus, best candidates underwent ex vivo testing against two distinct mechanisms implicated in hypertension: antagonism of the Ang II type 1 receptor and the blockade of calcium channel. Molecular docking studies helped to understand at the molecular level the dual vasorelaxant effects with the recognition sites of the AT1R and the L-type calcium channel. In an in vivo spontaneously hypertensive rat model (SHR), intraperitoneally administration of compound 1 at 20 mg/kg resulted in a 25 % reduction in systolic blood pressure, demonstrating both ex vivo vasorelaxant action and in vivo antihypertensive multitarget efficacy. ©2024 Elsevier.

Subcritical Water Extraction of Undaria pinnatifida: Comparative Study of the Chemical Properties and Biological Activities across Different Parts.

The subcritical water extraction of Undaria pinnatifida (blade, sporophyll, and root) was evaluated to determine its chemical properties and biological activities. The extraction was conducted at 180 °C and 3 MPa. Root extracts exhibited the highest phenolic content (43.32 ± 0.19 mg phloroglucinol/g) and flavonoid content (31.54 ± 1.63 mg quercetin/g). Sporophyll extracts had the highest total sugar, reducing sugar, and protein content, with 97.35 ± 4.23 mg glucose/g, 56.44 ± 3.10 mg glucose/g, and 84.93 ± 2.82 mg bovine serum albumin (BSA)/g, respectively. The sporophyll contained the highest fucose (41.99%) and mannose (10.37%), whereas the blade had the highest galactose (48.57%) and glucose (17.27%) content. Sporophyll had the highest sulfate content (7.76%). Key compounds included sorbitol, glycerol, L-fucose, and palmitic acid. Root extracts contained the highest antioxidant activity, with IC50 values of 1.51 mg/mL (DPPH), 3.31 mg/mL (ABTS+), and 2.23 mg/mL (FRAP). The root extract exhibited significant α-glucosidase inhibitory activity with an IC50 of 5.07 mg/mL, indicating strong antidiabetic potential. The blade extract showed notable antihypertensive activity with an IC50 of 0.62 mg/mL. Hence, subcritical water extraction to obtain bioactive compounds from U. pinnatifida, supporting their use in functional foods, cosmetics, and pharmaceuticals is highlighted. This study uniquely demonstrates the variation in bioactive compound composition and bioactivities across different parts of U. pinnatifida, providing deeper insights. Significant correlations between chemical properties and biological activities emphasize the use of U. pinnatifida extracts for chronic conditions.

Current insights and future perspectives of flavonoids: A promising antihypertensive approach.

Hypertension, or high blood pressure (BP), is a complex disease influenced by various risk factors. It is characterized by persistent elevation of BP levels, typically exceeding 140/90 mmHg. Endothelial dysfunction and reduced nitric oxide (NO) bioavailability play crucial roles in hypertension development. L-NG-nitro arginine methyl ester (L-NAME), an analog of L-arginine, inhibits endothelial NO synthase (eNOS) enzymes, leading to decreased NO production and increased BP. Animal models exposed to L-NAME manifest hypertension, making it a useful design for studying the hypertension condition. Natural products have gained interest as alternative approaches for managing hypertension. Flavonoids, abundant in fruits, vegetables, and other plant sources, have potential cardiovascular benefits, including antihypertensive effects. Flavonoids have been extensively studied in cell cultures, animal models, and, to lesser extent, in human trials to evaluate their effectiveness against L-NAME-induced hypertension. This comprehensive review summarizes the antihypertensive activity of specific flavonoids, including quercetin, luteolin, rutin, troxerutin, apigenin, and chrysin, in L-NAME-induced hypertension models. Flavonoids possess antioxidant properties that mitigate oxidative stress, a major contributor to endothelial dysfunction and hypertension. They enhance endothelial function by promoting NO bioavailability, vasodilation, and the preservation of vascular homeostasis. Flavonoids also modulate vasoactive factors involved in BP regulation, such as angiotensin-converting enzyme (ACE) and endothelin-1. Moreover, they exhibit anti-inflammatory effects, attenuating inflammation-mediated hypertension. This review provides compelling evidence for the antihypertensive potential of flavonoids against L-NAME-induced hypertension. Their multifaceted mechanisms of action suggest their ability to target multiple pathways involved in hypertension development. Nonetheless, the reviewed studies contribute to the evidence supporting the useful of flavonoids for hypertension prevention and treatment. In conclusion, flavonoids represent a promising class of natural compounds for combating hypertension. This comprehensive review serves as a valuable resource summarizing the current knowledge on the antihypertensive effects of specific flavonoids, facilitating further investigation and guiding the development of novel therapeutic strategies for hypertension management.

Combined eutexia and amorphization for simultaneous enhancement of dissolution rate of triamterene and hydrochlorothiazide: preparation of orodispersible tablets.

BACKGROUND: Triamterene is an oral antihypertensive drug with dissolution-limited poor bioavailability. It can be used as monotherapy or in fixed dose combination with hydrochlorothiazide which also suffers from poor dissolution. Moreover, co-processing of drugs in fixed dose combination can alter their properties. Accordingly, pre-formulation studies should investigate the effect of co-processing and optimize the dissolution of drugs before and after fixed dose combination. This is expected to avoid deleterious interaction (if any) and to hasten the biopharmaceutical properties. OBJECTIVE: Accordingly, the aim of this work was to optimize the dissolution rate of triamterene alone and after fixed dose combination with hydrochlorothiazide. METHODOLOGY: Triamterene was subjected to dry co-grinding with xylitol, HPMC-E5 or their combination. The effect of co-grinding with hydrochlorothiazide was also tested in absence and presence of xylitol and HPMC-E5. The products were assessed using Fourier-transform infrared (FTIR), differential scanning calorimetry, X-ray powder diffraction (XRPD), in addition to dissolution studies. Optimum formulations were fabricated as oral disintegrating tablets (ODT).Results: Co-processing of triamterene with xylitol formed eutectic system which hastened dissolution rate. HPMC-E5 resulted in partial amorphization and improved triamterene dissolution. Co-grinding with both materials combined their effects. Co-processing of triamterene with hydrochlorothiazide resulted in eutexia but the product was slowly dissolving due to aggregation. This problem was vanished in presence of HPMC-E5 and xylitol. Compression of the optimum formulation into ODT underwent fast disintegration and liberated acceptable amounts of both drugs. CONCLUSION: The study introduced simple co-processing with traditional excipients for development of ODT of triamterene and hydrochlorothiazide.

Vicinal diaryl pyrazole with tetrazole/urea scaffolds as selective angiotensin converting enzyme-1/cyclooxygenase-2 inhibitors: Design, synthesis, anti-hypertensive, anti-fibrotic, and anti-inflammatory.

As a hybrid weapon, two novel series of pyrazoles, 16a-f and 17a-f, targeting both COX-2 and ACE-1-N-domain, were created and their anti-inflammatory, anti-hypertensive, and anti-fibrotic properties were evaluated. In vitro, 17b and 17f showed COX-2 selectivity (SI = 534.22 and 491.90, respectively) compared to celecoxib (SI = 326.66) and NF-κB (IC50 1.87 and 2.03 µM, respectively). 17b (IC50 0.078 µM) and 17 f (IC50 0.094 µM) inhibited ACE-1 comparable to perindopril (PER) (IC50 0.048 µM). In vivo, 17b decreased systolic blood pressure by 18.6%, 17b and 17f increased serum NO levels by 345.8%, and 183.2%, respectively, increased eNOS expression by 0.97 and 0.52 folds, respectively and reduced NF-κB-p65 and P38-MAPK expression by -0.62, -0.22, -0.53, and -0.24 folds, respectively compared to  l-NAME (-0.34, -0.45 folds decline in NF-κB-p65 and P38-MAPK, respectively). 17b reduced ANG-II expression which significantly reversed the cardiac histological changes induced by L-NAME.

Hypotensive and Cardioprotective Potential of Yellow Bedstraw Extract-Based Oral Liquid in Spontaneously Hypertensive Rats.

This study aimed to prepare, characterize and assess the antioxidant activity of yellow bedstraw extracts (YBEs), focusing on identifying extracts with high antioxidant capacity. The selected extract was loaded into an oral liquid formulation and further investigated for its therapeutic potential in reducing blood pressure and associated complications in spontaneously hypertensive Wistar kyoto rats (SHR). Rats were divided into untreated SHR and SHR treated with a YBE-based oral formulation over four weeks. After treatment, blood pressure was measured, and cardiac function was assessed using the Langendorff technique to simulate ex vivo ischemic conditions. Prooxidant levels were assessed in plasma while antioxidant activity was evaluated in red blood cells. Histological analyses of heart, kidney, and liver samples were conducted to assess pathological changes induced by hypertension. Our results showed that the oral formulation loaded with ethanol YBE effectively reduced blood pressure, preserved myocardial function under ischemic stress, and decreased oxidative stress markers in blood. Importantly, our formulation with YBE demonstrated potential in attenuating structural kidney damage associated with hypertension. Overall, these findings suggest a cardioprotective effect of orally administered YBE formulation, highlighting its potential as an herbal supplement. However, clinical studies are warranted to validate these findings and explore the extract's suitability for clinical use.

Angiotensin-Converting Enzyme and Renin-Inhibitory Activities of Protein Hydrolysates Produced by Alcalase Hydrolysis of Peanut Protein.

Hypertension is a major controllable risk factor associated with cardiovascular disease (CVD) and overall mortality worldwide. Most people with hypertension must take medications that are effective in blood pressure management but cause many side effects. Thus, it is important to explore safer antihypertensive alternatives to regulate blood pressure. In this study, peanut protein concentrate (PPC) was hydrolyzed with 3-5% Alcalase for 3-10 h. The in vitro angiotensin-converting enzyme (ACE) and renin-inhibitory activities of the resulting peanut protein hydrolysate (PPH) samples and their fractions of different molecular weight ranges were determined as two measures of their antihypertensive potentials. The results show that the crude PPH produced at 4% Alcalase for 6 h of hydrolysis had the highest ACE-inhibitory activity with IC50 being 5.45 mg/mL. The PPH samples produced with 3-5% Alcalase hydrolysis for 6-8 h also displayed substantial renin-inhibitory activities, which is a great advantage over the animal protein-derived bioactive peptides or hydrolysate. Remarkably higher ACE- and renin-inhibitory activities were observed in fractions smaller than 5 kDa with IC50 being 0.85 and 1.78 mg/mL. Hence, the PPH and its small molecular fraction produced under proper Alcalase hydrolysis conditions have great potential to serve as a cost-effective anti-hypertensive ingredient for blood pressure management.

Establishing the Thermodynamic Cards of Dipine Models' Oxidative Metabolism on 21 Potential Elementary Steps.

Dipines are a type of important antihypertensive drug as L-calcium channel blockers, whose core skeleton is the 1,4-dihydropyridine structure. Since the dihydropyridine ring is a key structural factor for biological activity, the thermodynamics of the aromatization dihydropyridine ring is a significant feature parameter for understanding the mechanism and pathways of dipine metabolism in vivo. Herein, 4-substituted-phenyl-2,6-dimethyl-3,5-diethyl-formate-1,4-dihydropyridines are refined as the structurally closest dipine models to investigate the thermodynamic potential of dipine oxidative metabolism. In this work, the thermodynamic cards of dipine models' aromatization on 21 potential elementary steps in acetonitrile have been established. Based on the thermodynamic cards, the thermodynamic properties of dipine models and related intermediates acting as electrons, hydrides, hydrogen atoms, protons, and two hydrogen ions (atoms) donors are discussed. Moreover, the thermodynamic cards are applied to evaluate the redox properties, and judge or reveal the possible oxidative mechanism of dipine models.

HPLC-Based Metabolomic Analysis and Characterization of Amaranthus cruentus Leaf and Inflorescence Extracts for Their Antidiabetic and Antihypertensive Potential.

The aim of this study was to investigate the potential of Amaranthus cruentus flavonoids (quercetin, kaempferol, catechin, hesperetin, naringenin, hesperidin, and naringin), cinnamic acid derivatives (p-coumaric acid, ferulic acid, and caffeic acid), and benzoic acids (vanillic acid and 4-hydroxybenzoic acid) as antioxidants, antidiabetic, and antihypertensive agents. An analytical method for simultaneous quantification of flavonoids, cinnamic acid derivatives, and benzoic acids for metabolomic analysis of leaves and inflorescences from A. cruentus was developed with HPLC-UV-DAD. Evaluation of linearity, limit of detection, limit of quantitation, precision, and recovery was used to validate the analytical method developed. Maximum total flavonoids contents (5.2 mg/g of lyophilized material) and cinnamic acid derivatives contents (0.6 mg/g of lyophilized material) were found in leaves. Using UV-Vis spectrophotometry, the maximum total betacyanin contents (74.4 mg/g of lyophilized material) and betaxanthin contents (31 mg/g of lyophilized material) were found in inflorescences. The leaf extract showed the highest activity in removing DPPH radicals. In vitro antidiabetic activity of extracts was performed with pancreatic α-glucosidase and intestinal α-amylase, and compared to acarbose. Both extracts exhibited a reduction in enzyme activity from 57 to 74%. Furthermore, the in vivo tests on normoglycemic murine models showed improved glucose homeostasis after sucrose load, which was significantly different from the control. In vitro antihypertensive activity of extracts was performed with angiotensin-converting enzyme and contrasted to captopril; both extracts exhibited a reduction of enzyme activity from 53 to 58%. The leaf extract induced a 45% relaxation in an ex vivo aorta model. In the molecular docking analysis, isoamaranthin and isogomphrenin-I showed predictive binding affinity for α-glucosidases (human maltase-glucoamylase and human sucrase-isomaltase), while catechin displayed binding affinity for human angiotensin-converting enzyme. The data from this study highlights the potential of A. cruentus as a functional food.

Development and Evaluation of Solidified Supersaturated SNEDDS Loaded with Triple Combination Therapy for Metabolic Syndrome.

The present study aimed to develop and optimize solidified supersaturated self-nanoemulsifying drug delivery systems (SNEDDS) for the combined administration of antihypertensive, antihyperglycemic, and antihyperlipidemic drugs to enhance their solubility and dissolution during the treatment of metabolic syndrome. Various SNEDDS formulations were prepared and subjected to pharmaceutical assessment. The solubility of candesartan (CC), glibenclamide (GB), and rosuvastatin (RC) in SNEDDS and supersaturated SNEDDS formulations was evaluated. The optimized formulation was solidified using Syloid adsorbent at different ratios. Pharmaceutical characterization of the formulations included particle size, zeta potential, in-vitro dissolution, PXRD, FTIR, and SEM analysis. The prepared optimized formulation (F6) was able to form homogeneous nanoemulsion droplets without phase separation, which is composed of Tween 20: PEG-400: Capmul MCM (4: 3: 3). It was mixed with 5% PVP-K30 to prepare a supersaturated liquid SNEDDS formulation (F9). In addition, it was found that the addition of PVP-K30 significantly increased solubility CC and GB from 20.46 ± 0.48 and 6.73 ± 0.05 to 27.67 ± 1.72 and 9.45 ± 0.32 mg/g, respectively. In-vitro dissolution study revealed that liquid and solid SNEDD formulations remarkably improved the dissolution rates of CC, GB, and RC compared to pure drugs. XRPD and FTIR analysis revealed that all drugs present in an amorphous state within prepared solidified supersaturated SNEDDS formulation. SEM images showed that liquid SNEDDS formulation was successfully adsorbed on the surface of Syloid. Overall, optimized F9 and solidified supersaturated SNEDDS formulations showed superior performance in enhancing drug solubility and dissolution rate. The present study revealed that the proposed triple combination therapy of metabolic syndrome holds a promising strategy during the treatment of metabolic syndrome. Further in-vivo studies are required to evaluate the therapeutic efficacy of prepared solidified supersaturated SNEDDS formulation.

Identification and Molecular Docking Analysis of Angiotensin-Converting Enzyme Inhibitors from Finger Millet (Eleusine coracana).

Hypertension remains a significant global health concern, contributing significantly to cardiovascular diseases and mortality rates. The inhibition of angiotensin-converting enzyme (ACE) plays a crucial role in alleviating high blood pressure. We investigated the potential of finger millets (Eleusine coracana) as a natural remedy for hypertension by isolating and characterizing its ACE-inhibitory compound. First, we evaluated the ACE-inhibitory activity of the finger millet ethanol extract and subsequently proceeded with solvent fractionation. Among the solvent fractions, the ethyl acetate fraction exhibited the highest ACE inhibitory activity and was further fractionated. Using preparative high-performance liquid chromatography, the ethyl acetate fraction was separated into four subfractions, with fraction 2 (F2) exhibiting the highest ACE inhibitory activity. Subsequent 1 H-nuclear magnetic resonance (NMR) and 13 C-NMR analyses confirmed that the isolated compound from F2 was catechin. Furthermore, molecular docking studies indicated that catechin has the potential to act as an ACE inhibitor. These findings suggest that finger millets, particularly as a source of catechin, have the potential to be used as a natural antihypertensive.

ISOLATION, CHARACTERIZATION, AND ANTIHYPERTENSIVE ACTIVITY ALKALOIDS EXTRACTED FROM THE LEAVES OF THE ALSTONIA SCHOLARIS PLANT.

The study aims to investigate the Isolation, Characterization & Antihypertensive Life of Natural Alkaloids out of certain Selected Plants. The Alstonia scholaris papers used in this study are generally available in the tropics and can be obtained in Asia. The plant sample was verified by the pharmacognosy and pharmacology department. The powdered leaves of Alstonia scholaris (500 gm) are macerated using 1% HCl (pH 2) at space temperature overnight. After that, the combination was produced alkaline by putting 25% NH4OH solution (pH 9). The combination's color changed from the red wine to the black. The alkaline mixture was then bounced satisfactorily and purified using Whatman filter paper. Four fractions (15-19) were collected from column chromatography. All the fractions have shown the same Rf value in the TLC fingerprint, therefore they are incorporated established on TLC analysis generated in Hexane: Ethyl acetate (14:6). Nitric oxide synthase inhibitor, i.e. N-nitro-L-arginine methyl ester was used to produce hypertension in rats in (40 mg/ml/kg, i.p.). Every day, it is solubilized in 0.9 per cent NaCl solution. Colourless powder compound was obtained (yield 0.4%) and having MP 132-1340 C. Rf value in (Hexane: Ethyl acetate,65:35) at 0.55, UV-Vis λmax in methanol: (nm) 297, IR (KBr), m 913 (N-H bending), 1260 (C-N Stretching), 1396 (C-N), 1165, 1259 (-C-O- stretching) 1396, 1464 (C=C, Ar.), 2831, 2928 (C-H, Aliphatic) and 3564, 3315 (N-H Stretching). The 1H NMR spectrum also portrayed the distinctive peaks for various chemical compounds. The peak of 7.28-8.85 ppm was due to multiple aromatic protons. The 6.94-7.04 ppm peaks were characteristic of ethylene amino protons, and the 1.57-2 ppm peaks were allocated to alcohol protons. L-NAME significantly elevated MABP, SBP, and DBP in pentobarbital-anesthetized rats but not HR. The mean arterial blood pressure, systolic blood pressure and diastolic blood pressure of pentobarbital-anaesthetized L-NAME caused hypertensive rats do not alter after a single intragastric injection of the isolated alkaloid. Finally, isolated alkaloids from Alstonia scholaris supplement had antihypertensive properties in hypertensive rats.

Machine annealing-guided navigation of antihypertensive food peptide selectivity between human ACE N- and C-domains in structurally interacting diversity space.

Human angiotensin-converting enzyme (ACE) is a well-established druggable target for the treatment of hypertension (HTN), which contains two structurally homologous but functionally distinct N- and C-domains. Selective inhibition of the C-domain primarily contributes to the antihypertensive efficiency and can be exploited as medicinal agents and functional additives for regulating blood pressure with high safety. In this study, we used a machine annealing (MA) strategy to guide the navigation of antihypertensive peptides (AHPs) in structurally interacting diversity space with the two ACE domains based on their crystal/modeled complex structures and an in-house protein-peptide affinity scoring function, aiming to optimize the peptide selectivity for C-domain over N-domain. The strategy generated a panel of theoretically designed AHP hits with a satisfactory C-over-N (C > N) selectivity profile, from which several hits were found to have a good C > N selectivity, which is roughly comparable with or even better than the BPPb, a natural C > N-selective ACE-inhibitory peptide. Structural analysis and comparison of domain-peptide noncovalent interaction patterns revealed that (i) longer peptides (>4 amino aids) generally exhibit stronger selectivity than shorter peptides (<4 amino aids), (ii) peptide sequence can be divided into two, section I (including peptide C-terminal region) and section II (including peptide middle and N-terminal regions); the former contributes to both peptide affinity (primarily) and selectivity (secondarily), while the latter is almost only responsible for peptide selectivity, and (iii) charged/polar amino acids confer to peptide selectivity relative to hydrophobic/nonpolar amino acids (that confer to peptide affinity).

Ameliorative effect of mussel-derived ACE inhibitory peptides on spontaneous hypertension rats.

PURPOSE: The purpose of this study was to prepare the novel mussel-derived ACE inhibitory peptides (MEPs) by enzymatic hydrolysis of Mytilus edulis and investigate their antihypertensive effects in vivo. METHODS: After assessing the stability of MEPs in vitro, we investigated the effect of MEPs on hypertension using spontaneously hypertensive rats (SHRs). Subsequently, MEPs were purified and identified by ultrafiltration, gel filtration chromatography and liquid chromatography-tandem mass spectrometry (LC-MS/MS). RESULTS: Our study demonstrated that MEPs could keep stable ACE inhibitory activity after treatment with heat, acid, alkali, metal ions and simulated gastrointestinal digestive fluid. Additionally, the animal experiments showed that both short-term and long-term treatment with MEPs resulted in a significant reduction in systolic and diastolic blood pressure in SHRs. Mechanistically, the results suggested that MEPs could reduce vascular remodeling, regulate renin-angiotensin system (RAS), and inhibit kidney and myocardial fibrosis. Finally, we isolated and identified five peptides from MEPs, with the peptide Ile-Leu-Thr-Glu-Arg showed the highest ACE inhibition rate. CONCLUSION: Our findings demonstrate the potential use of MEPs as active components in functional foods designed to lower blood pressure.

Identification of ACE I-Inhibitory Peptides Released by the Hydrolysis of Tub Gurnard (Chelidonichthys lucerna) Skin Proteins and the Impact of Their In Silico Gastrointestinal Digestion.

Tub gurnard is a highly abundant fishery species caught as a discard in the Mediterranean Sea. This work proposes its valorisation through the release of potential antihypertensive peptides and glycosaminoglycans (GAGs) through the controlled hydrolysis of tub gurnard skin proteins. Four proteases (Esperase, Alcalase, Trypsin and Pronase E) were used to obtain potent angiotensin converting enzyme I (ACE)-inhibitory hydrolysates. Peptides and GAGs were separated and evaluated for their antihypertensive potential by fluorometry. The peptide-rich fractions derived from the Esperase and Alcalase hydrolysates showed very low IC50 values (47 and 68 µg/mL, respectively). Only the GAGs from the Trypsin and Esperase hydrolysates were relevant ACE inhibitors (63 and 52% at 1 mg/mL, respectively). The peptide composition of the most potent ACE-inhibitory fractions derived from the Esperase and Alcalase hydrolysates (IC50 values of 33 and 29 µg/mL, respectively) was analysed by RP-LC-ESI-MS/MS. The analysis suggests that the ACE-inhibitory activity is related to the peptide hydrophobicity, as well as to the presence of specific residues at any of the last four C-terminal positions. The in silico gastrointestinal digestion of these fractions yielded small peptides with antihypertensive potential.

Anchoring of Polymer Loops on Enzyme-Immobilized Mesoporous ZIF-8 Enhances the Recognition Selectivity of Angiotensin-Converting Enzyme Inhibitory Peptides.

Immobilized angiotensin-converting enzyme (ACE) is a promising material for the rapid screening of antihypertensive drugs, but the nonspecific adsorption is a serious problem in separation processes involving complex biological products. In this study, triblock copolymers with dopamine (DA) block as anchors and PEG block as the main body (DA-PEGx-DA) were attached to an immobilized ACE (ACE@mZIF-8/PDA, AmZP) surface via the "grafting to" strategy which endowed them with anti-nonspecific adsorption. The influence of DA-PEGx-DA chain length on nonspecific adsorption was confirmed. The excellent specificity and reusability of the obtained ACE@mZIF-8/PDA/DA-PEG5000-DA (AmZPP5000) was validated by screening two known ACE inhibitory peptides Val-Pro-Pro (VPP, competitive inhibitory peptides of ACE) and Gly-Met-Lys-Cys-Ala-Phe (GF-6, noncompetitive inhibitory peptides of ACE) from a mixture containing active and inactive compounds. These results demonstrate that anchored polymer loops are effective for high-recognition selectivity and AmZPP5000 is a promising compound for the efficient separation of ACE inhibitors in biological samples.

Antihypertensive activity of orally consumed ACE-I inhibitory peptides.

Food proteins are sources for ACE-I inhibitory peptides that can be extracted by enzymatic hydrolysis exhibiting anti-hypertensive activity. However, these peptides are prone to further degradation by gastrointestinal enzymes during oral consumption. Bio-activity of these peptides is dependent on the resultant peptide post gastrointestinal digestion. To exhibit the bio-activity, they need to be absorbed in intact form. Although studies suggest di and tri-peptides show better ACE-I inhibitory activity, few peptides show altered IC50 values under simulated gastrointestinal digestion. Moreover, ACE-I inhibitory peptides with low IC50 values have not shown effective anti-hypertensive activity in spontaneously hypertensive rats when administered orally. Few ACE-I inhibitory peptides have reported effective reduction in systolic blood-pressure when administered through intravenously. During oral consumption of such peptides, the actual peptide sequence responsible for reducing blood-pressure is a result of breakdown in gastrointestinal tract. The fate of targeted peptides during digestion depends on amino acid sequence of the protein containing the specific site for cleavage where the action of digestive enzymes takes place. Therefore, this review attempts to explain the factors that affect the anti-hypertensive activity of ACE-I inhibitory peptides during oral consumption. It also highlights subsequent absorption of ACE-I inhibitory peptides after gastrointestinal digestion.

PTML modeling for peptide discovery: in silico design of non-hemolytic peptides with antihypertensive activity.

Hypertension is a medical condition that affects millions of people worldwide. Despite the high efficacy of the current antihypertensive drugs, they are associated with serious side effects. Peptides constitute attractive options for chemical therapy against hypertension, and computational models can accelerate the design of antihypertensive peptides. Yet, to the best of our knowledge, all the in silico models predict only the antihypertensive activity of peptides while neglecting their inherent toxic potential to red blood cells. In this work, we report the first sequence-based model that combines perturbation theory and machine learning through multilayer perceptron networks (SB-PTML-MLP) to enable the simultaneous screening of antihypertensive activity and hemotoxicity of peptides. We have interpreted the molecular descriptors present in the model from a physicochemical and structural point of view. By strictly following such interpretations as guidelines, we performed two tasks. First, we selected amino acids with favorable contributions to both the increase of the antihypertensive activity and the diminution of hemotoxicity. Then, we assembled those suitable amino acids, virtually designing peptides that were predicted by the SB-PTML-MLP model as antihypertensive agents exhibiting low hemotoxicity. The potentiality of the SB-PTML-MLP model as a tool for designing potent and safe antihypertensive peptides was confirmed by predictions performed by online computational tools reported in the scientific literature. The methodology presented here can be extended to other pharmacological applications of peptides.