Angiotensin I-converting Enzyme Activity Research Articles

Lasianthera Africana leaves inhibits α-amylase α-glucosidase, angiotensin-I converting enzyme activities and Fe2+-induced oxidative damage in pancreas and kidney homogenates

Lasianthera africana is a dark green leafy vegetable commonly consumed as food and used for treatment of several human ailments in Nigeria most especially south-east. This study investigated the phenolic composition and effects of methanol extract from L. africana leaves on enzymes linked to type-2 diabetes (α-amylase and α-glucosidase) and hypertension [angiotensin-1-converting enzymes (ACE)] as well as Fe2+-induced lipid peroxidation in rat’s pancreas and kidney homogenates were evaluated. Phenolic contents and constituents were also determined using colorimetric methods and high performance liquid chromatography-diode array detector (HPLC-DAD) respectively. Our findings revealed that the extract inhibited α-amylase, α-glucosidase and ACE activities with IC50 values of 0.192 and 0.21 mg/mL, and 57.06 μg/mL respectively. The extract also inhibited Fe2+-induced lipid peroxidation in rats’ pancreas and kidney homogenates. Our findings revealed that the extract is rich in phenolic acids such as caffeic acid (59.97 mg/g), chlorogenic acid (58.23 mg/g) and ellagic acid (31.16 mg/g) as well as flavonoids such as quercetin (42.98 mg/g). These results give a clue to the potential use of L. africana leaves as an alternative agent for the control of glucose absorption and lowering of blood pressure in diabetic patients with hypertension.

STRUCTURAL CHARACTERISTICS AND ANTIHYPERTENSIVE EFFECTS OF ANGIOTENSIN-I-CONVERTING ENZYME INHIBITORY PEPTIDES IN THE RENIN-ANGIOTENSIN AND KALLIKREIN KININ SYSTEMS.

Background:The commercially available synthetic angiotensin-I-converting enzyme (ACE) inhibitors are known to exert negative side effects which have driven many research groups globally to discover the novel ACE inhibitors.Method:Literature search was performed within the PubMed, ScienceDirect.com and Google Scholar.Results:The presence of proline at the C-terminal tripeptide of ACE inhibitor can competitively inhibit the ACE activity. The effects of other amino acids are less studied leading to difficulties in predicting potent peptide sequences. The broad specificity of the enzyme may be due to the dual active sites observed on the somatic ACE. The inhibitors may not necessarily competitively inhibit the enzyme which explains why some reported inhibitors do not have the common ACE inhibitor characteristics. Finally, the in vivo assay has to be carried out before the peptides as the antihypertensive agents can be claimed. The peptides must be absorbed into circulation without being degraded, which will affect their bioavailability and potency. Thus, peptides with strong in vitro IC50 values do not necessarily have the same effect in vivo and vice versa.Conclusion:The relationship between peptide amino acid sequence and inhibitory activity, in vivo studies of the active peptides and bioavailability must be studied before the peptides as antihypertensive agents can be claimed.

Profiles of free and bound phenolics extracted from Citrus fruits and their roles in biological systems: content, and antioxidant, anti-diabetic and anti-hypertensive properties.

This study of selected plants of the Rutaceae family was carried out to investigate their phenolic content, antioxidant activity, and the in vitro inhibitory potential of extracted phenolics towards enzymes relevant for hyperglycemia and hypertension. The phenolic content, antioxidant activity and phenolic extract-mediated inhibitory activities for α-glucosidase and α-amylase were evaluated by spectrophotometry. The content of individual phenolics and the angiotensin I-converting enzyme (ACE) inhibitory activity of the phenolic extracts were evaluated by LC/MS-MS and RP-HPLC methods, respectively. A higher percentage of free phenolic content was seen for all the selected plants of the Rutaceae family (85.43-92.82% of the total phenolic content) than of the bound form (7.18-14.57% of total phenolic content). The major predominant bound phenolic in lemon and red blood orange was hesperidin. The major predominant bound phenolic in pummelo, shamouti and clementine was ferulic acid. The highest ACE and α-glucosidase inhibitory activity of the extracted phenolics from lemon was associated with free phenolic extracts obtained at 30 °C with values of 100% inhibition. Red blood orange free phenolic extract (30 °C) elicited the highest α-amylase inhibition activity (32.3%). In contrast, extracted bound phenolics after acid and base hydrolysis from all selected plants from the Citrus species were shown to induce activation of the ACE and α-amylase enzymes.

Modulatory effects of Aqueous extract from Tetracarpidium conophorum leaves on key enzymes linked to erectile dysfunction and oxidative stress-induced lipid peroxidation in penile and testicular tissues

Tetracarpidium conophorum (walnut) is used in folk medicine for the treatment of erectile dysfunction but the mechanism remains unclear. This study evaluated the effect of aqueous extract from T conophorum leaves on oxidative stress-induced penile damage and key enzymes linked to erectile dysfunction. The inhibitory effect of the extract on sodium nitroprusside (SNP)-induced lipid peroxidation, arginase, angiotensin I-converting enzyme (ACE) and acetylcholinesterase (AChE) activities in penile and testicular tissue homogenates were determined via colorimetric method. The aqueous extract inhibited SNP-induced lipid peroxidation in rats penile and testicular homogenates in a dose dependent manner. The highest inhibitory effect was obtained in the penis at a concentration of 0.5 mg/mL. Furthermore, the extract inhibited arginase activity in a dose dependent pattern. The IC50 revealed that the extract had significantly (P

Imminent Angiotensin-converting Enzyme Inhibitor from Microbial Source for Cancer Therapy.

Background:Drugs targeting Angiotensin I-converting enzyme (ACE) have been used broadly in cancer chemotherapy. The recent past coupled with our results demonstrates the effective use of ACE inhibitors (ACEi) as anticancer agents, and they are potentially relevant in deriving new inhibitors.Methods:Bacterial strains were isolated from cow milk collected in Coimbatore, Tamil Nadu, India and plated on nutrient agar medium. The identity of the strain was ascertained by 16s rRNA gene sequencing method and was submitted to the NCBI GenBank nucleotide database. Various substrates were screened for ACEi production by the fermentation with the isolated strain. ACEi was purified by sequential steps of ethanol precipitation, ion exchange column chromatography and gel filtration column chromatography. The apparent molecular mass was determined by SDS-PAGE. The anticancer property was analyzed by studying the cytotoxicity effects of ACEi using Breast cancer MCF-7 cell linesResults:The isolate coded as BUCTL09 was selected and identified as Micrococcus luteus. Among the seven substrates, only beef extract fermented broth showed an inhibition of 79% and was reported as the best substrate. The peptide was purified and molecular mass was determined. The IC50 value of peptide was found to be 59.5 μg/ml. The purified peptide has demonstrated to induce apoptosis of cancer cell.Conclusions:The results of this study revealed that Peptide has been determined as an active compound that inhibited the activity of ACE. These properties indicate the possibilities of the use of purified protein as a potent anticancer agent.

Serum protease activity in chronic kidney disease patients: The GANI_MED renal cohort.

Serum or plasma proteases have been associated with various diseases including cancer, inflammation, or reno-cardiovascular diseases. We aimed to investigate whether the enzymatic activities of serum proteases are associated with the estimated glomerular filtration rate (eGFR) in patients with different stages of chronic kidney disease (CKD). Our study population comprised 268 participants of the "Greifswald Approach to Individualized Medicine" (GANI_MED) cohort. Enzymatic activity of aminopeptidase A, aminopeptidase B, alanyl (membrane) aminopeptidase, insulin-regulated aminopeptidase, puromycin-sensitive aminopeptidase, leucine aminopeptidase 3, prolyl-endopeptidase (PEP), dipeptidyl peptidase 4 (DPP4), angiotensin I-converting enzyme, and angiotensin I-converting enzyme 2 (ACE2) proteases was measured in serum. Linear regression of the respective protease was performed on kidney function adjusted for age and sex. Kidney function was modeled either by the continuous Modification of Diet in Renal Disease (MDRD)-based eGFR or dichotomized by eGFR < 15 mL/min/1.73 m2 or <45 mL/min/1.73 m2, respectively. Results with a false discovery rate below 0.05 were deemed statistically significant. Among the 10 proteases investigated, only the activities of ACE2 and DPP4 were correlated with eGFR. Patients with lowest eGFR exhibited highest DPP4 and ACE2 activities. DPP4 and PEP were correlated with age, but all other serum protease activities showed no associations with age or sex. Our data indicate that ACE2 and DPP4 enzymatic activity are associated with the eGFR in patients with CKD. This finding distinguishes ACE2 and DPP4 from other serum peptidases analyzed and clearly indicates that further analyses are warranted to identify the precise role of these serum ectopeptidases in the pathogenesis of CKD and to fully elucidate underlying molecular mechanisms. Impact statement • Renal and cardiac diseases are very common and often occur concomitantly, resulting in increased morbidity and mortality. Understanding of molecular mechanisms linking both diseases is limited, available fragmentary data point to a role of the renin-angiotensin system (RAS) and, in particular, Ras-related peptidases. • Here, a comprehensive analysis of serum peptidase activities in patients with different stages of chronic kidney disease (CKD) is presented, with special emphasis given to RAS peptidases • The serum activities of the peptidases angiotensin I-converting enzyme 2 and dipeptidyl peptidase 4 were identified as closely associated with kidney function, specifically with the estimated glomerular filtration rate. The findings are discussed in the context of available data suggesting protective roles for both enzymes in reno-cardiac diseases. • The data add to our understanding of pathomechanisms underlying development and progression of CKD and indicate that both enzymes might represent potential pharmacological targets for the preservation of renal function.

Evaluation of Bacillus subtilis SPB1 biosurfactant effects on hyperglycemia, angiotensin I-converting enzyme (ACE) activity and kidney function in rats fed on high-fat–high-fructose diet

This study investigated the protective and the curative effects of Bacillus subtilis SPB1 crude lipopeptide biosurfactant in alleviating induced obesity complications in rats fed on high-fat–high-fructose diet (HFFD). Male Wistar rats were divided into five groups with the following treatment schedule: normal diet-fed rats (CD), HFFD-fed rats, HFFD-fed rats supplemented with SPB1 biosurfactant from the first day of the experiment (HFFD + Bios1), rats fed on HFFD receiving standard drug (HFFD + Torva), or SPB1 biosurfactant (HFFD + Bios2) during the last 4 weeks of the study. HFFD induced hyperglycemia, manifested by a significant (p < 0.001) increase (20%) in the levels of glucose and α-amylase activity in the plasma, when compared with CD. The administration of SPB1 biosurfactant to rats fed on HFFD reverted back normal blood glucose and α-amylase activity levels. Also, the findings clearly showed that acute oral administration of SPB1 biosurfactant reduced significantly (34%) the peak of blood glucose concentration 60 min after glucose administration, as compared with untreated rats fed on HFFD. Furthermore, renal dysfunction indices such as creatinine and urea as well as the level of angiotensin I-converting enzyme (ACE) exhibited remarkable increases in serum of rats fed on HFFD by 28.35%, 46%, and 92%,. Interestingly, SPB1 lipopeptides treatments decreased the creatinine and urea levels significantly (p < 0.001) near normal values, as compared with that of the HFFD group, and also showed an improvement of the kidney cortex architecture. Moreover, SPB1 biosurfactant displayed a potent inhibition of ACE activity in vitro (CI50 value= 1.37 mg/mL) as well as in vivo in obese rats by 42% and 27.25% with HFFD + Bios1 and HFFD + Bios2 treatments, respectively, and comparatively with the HFFD group. Besides, SPB1 lipopeptides treatments improved some of serum electrolytes such as Na+, K+, Ca2+ , and Mg2+. The results showed that SPB1 lipopeptide biosurfactant presented useful hypoglycemic and antihypertensive properties, and was able to alleviate renal lipid deposition in rats fed on a hypercaloric diet.

Discovery of Anti-Hypertensive Oligopeptides from Adlay Based on In Silico Proteolysis and Virtual Screening.

Adlay (Coix larchryma-jobi L.) was the commonly used Traditional Chinese Medicine (TCM) with high content of seed storage protein. The hydrolyzed bioactive oligopeptides of adlay have been proven to be anti-hypertensive effective components. However, the structures and anti-hypertensive mechanism of bioactive oligopeptides from adlay were not clear. To discover the definite anti-hypertensive oligopeptides from adlay, in silico proteolysis and virtual screening were implemented to obtain potential oligopeptides, which were further identified by biochemistry assay and molecular dynamics simulation. In this paper, ten sequences of adlay prolamins were collected and in silico hydrolyzed to construct the oligopeptide library with 134 oligopeptides. This library was reverse screened by anti-hypertensive pharmacophore database, which was constructed by our research team and contained ten anti-hypertensive targets. Angiotensin-I converting enzyme (ACE) was identified as the main potential target for the anti-hypertensive activity of adlay oligopeptides. Three crystal structures of ACE were utilized for docking studies and 19 oligopeptides were finally identified with potential ACE inhibitory activity. According to mapping features and evaluation indexes of pharmacophore and docking, three oligopeptides were selected for biochemistry assay. An oligopeptide sequence, NPATY (IC50 = 61.88 ± 2.77 µM), was identified as the ACE inhibitor by reverse-phase high performance liquid chromatography (RP-HPLC) assay. Molecular dynamics simulation of NPATY was further utilized to analyze interactive bonds and key residues. ALA354 was identified as a key residue of ACE inhibitors. Hydrophobic effect of VAL518 and electrostatic effects of HIS383, HIS387, HIS513 and Zn2+ were also regarded as playing a key role in inhibiting ACE activities. This study provides a research strategy to explore the pharmacological mechanism of Traditional Chinese Medicine (TCM) proteins based on in silico proteolysis and virtual screening, which could be beneficial to reveal the pharmacological action of TCM proteins and provide new lead compounds for peptides-based drug design.

Enzymatic production of protein hydrolysates from steelhead (Oncorhynchus mykiss) skin gelatin as inhibitors of dipeptidyl-peptidase IV and angiotensin-I converting enzyme

The objective of this study was to generate protein hydrolysates with dual in vitro inhibitory activities against dipeptidyl-peptidase IV (DPP-IV) and angiotensin-I converting enzyme (ACE), by proteolytic enzymes acting either individually or sequentially on steelhead skin gelatin. The results showed strong dual bioactivity in the low molecular weight (<3kDa) fractions obtained by ultrafiltration of hydrolysates produced using the enzymes pepsin, CorolaseN or papain. Alternatively, unfractionated hydrolysates exhibiting high ACE and DPP-IV inhibitory activities as well as yields could be attained by strategic selection of two enzymes for successive hydrolysis of gelatin. In particular, hydrolysates produced using 4% papain for 2h followed either by ultrafiltration or by a second hydrolysis with 1% CorolaseN for 2h, presented potent dual activity as ACE and DPP-IV inhibitors, and should be investigated further as potential functional food ingredients or nutraceuticals for the management of hypertension and diabetes.

Inhibitory activities of Cystoseira crinita sulfated polysaccharide on key enzymes related to diabetes and hypertension: in vitro and animal study

The present study investigated the effect of the Cystoseira crinita sulfated polysaccharide (CCSP) on key enzymes activities related to diabetes in vitro and in diabetic rats. We found that CCSP inhibited pancreatic α-amylase with IC50 = 39.16 μg/ml and angiotensin I-converting enzyme (ACE) activity with IC50 = 58.35 μg/ml in vitro. In diabetic rats, the administration of CCSP reduced the activity of α-amylase in serum, pancreas, and intestine by 23%, 44.38%, and 45%, respectively as compared to untreated diabetic rats. Moreover, the administration of CCSP to surviving diabetic rats protects pancreas β cells from death and damage, which leads to insulin levels. The decrease in α-amylase and the increase in insulin level lead to a decrease in glucose rate by 56% as compared to untreated diabetic rats. The inhibitory action of α-amylase activity and hypoglycemic effect of CCSP were confirmed by oral glucose tolerance test (OGTT). In addition, the administration of CCSP to surviving diabetic rats normalizes lipid profile, stimulates antioxidant capacity, and prevents liver–kidney toxicities, evidenced by decrease in serum indices of liver and kidney toxicity and confirmed by histological analysis. The overall findings presented in this study demonstrate that the administration of CCSP to diabetic rats can make it a potentially strong candidate for industrial application as a pharmacological agent for the treatment of hyperglycemia, hyperlipidemia, and liver–kidney dysfunctions.

In Silico, In Vitro and In Vivo Toxicological Assessment of BPP-BrachyNH2, A Vasoactive Proline-Rich Oligopeptide from Brachycephalus ephippium

BPP-BrachyNH2 is a proline-rich oligopeptide (PRO) firstly identified in skin secretion of the frog Brachycephalus ephippium, which possess in vitro inhibitory activity of angiotensin-I converting enzyme (ACE) and endothelium-dependent vasorelaxant activity. Considering its potential application in the treatment of cardiovascular diseases, the present work assessed the toxicological profile of the BPP-BrachyNH2. The in silico toxicity prediction was performed from the best model obtained through the optimization of the FASTA query peptide. This prediction study revealed that BPP-BrachyNH2 induced high predicted LD50 values for both humans and rats, and then is well-tolerated in the recommended range. The MTT assay was applied for the in vitro cytotoxic evaluation in murine macrophages. In this assay, a decrease of cell viability was not observed. The in vivo acute toxicological study was performed after the intraperitoneal administration of BPP-BrachyNH2 at doses of 5 and 50 mg/kg. After intraperitoneal administration, no death, alterations in behavioral parameters or weight gain curve was observed, as well as none in the serum biochemical parameters, and gross pathological and histopathological analyses. These observations demonstrates an acceptable safety profile for BPP-BrachyNH2, leading towards further studies focused on investigation of pharmacological and therapeutical applications for this peptide.

Effect of some Tropical Eggplant Fruits (Solanum Spp) Supplemented Diet On Diabetic Neuropathy In Experimental male Wistar Rats In-vivo

Background: Solanum known as eggplant is a popular vegetable crop grown in the subtropics and tropics. Eggplant is a perennial but grown commercially as an annual crop. The fruits of eggplant is primarily used as a cooking vegetable for various dishes. Eggplant comes in various kinds of species, which are highly variable for its fruit colour, as well as shape and size.Content and Purpose of this study: This study focused on comparing the effect of dietary African eggplants (AP) Solanum kumba,(PG) Solanum gilo (PW) and Solanum aethiopicum (PGW) species. Diabetes was induced experimentally by high fat fed/low dose streptozotocin-diabetic rats (35 mg/kg body wt.) and the diabetic rats were fed diets supplemented with 20–40% supplemented eggplant diet for 14 days. The effect of the diets on the blood glucose level, pancreatic α-amylase, intestinal α-glucosidase and Angiotensin-I converting enzyme (ACE) activities, plasma antioxidant status were determined also quantification of the fruits polyphenols using HPLC/DAD .Results: The results revealed that there was no significant (P &lt; 0.05) difference in the average feed intake and weight changes in all the groups. Supplementation with eggplant diet gradually reduced blood glucose level in diabetic rat compared to diabetic rats and metformin-treated (positive control group). African eggplant showed elevated levels of antioxidant status such as (glutathione peroxidase GPX, glutathione transferase GST,reduced glutathione GSH,Catalase and Ascorbic acid).Conclusions:The results suggest that the eggplant may attenuate hyperglycemia, hypertension and oxidative stress in the type 2 diabetic condition with Solanum kumba having the highest activity which could not be far fetched from its polyphenols as revealed in the HPLC/DAD characterization.Keywords: Solanum spp,polyphenols, diabetes,enzymes

Lysozyme and bilirubin bind to ACE and regulate its conformation and shedding.

Angiotensin I-converting enzyme (ACE) hydrolyzes numerous peptides and is a critical participant in blood pressure regulation and vascular remodeling. Elevated tissue ACE levels are associated with increased risk for cardiovascular and respiratory disorders. Blood ACE concentrations are determined by proteolytic cleavage of ACE from the endothelial cell surface, a process that remains incompletely understood. In this study, we identified a novel ACE gene mutation (Arg532Trp substitution in the N domain of somatic ACE) that increases blood ACE activity 7-fold and interrogated the mechanism by which this mutation significantly increases blood ACE levels. We hypothesized that this ACE mutation disrupts the binding site for blood components which may stabilize ACE conformation and diminish ACE shedding. We identified the ACE-binding protein in the blood as lysozyme and also a Low Molecular Weight (LMW) ACE effector, bilirubin, which act in concert to regulate ACE conformation and thereby influence ACE shedding. These results provide mechanistic insight into the elevated blood level of ACE observed in patients on ACE inhibitor therapy and elevated blood lysozyme and ACE levels in sarcoidosis patients.

Polyphenolic compositions and in vitro angiotensin-I-converting enzyme inhibitory properties of common green leafy vegetables: A comparative study.

This study compared the phenolic compositions of common green leafy vegetable extracts from Vernonia amygdalina (VA), Telfairia occidentalis (TO), Talinium triangulare (TT), and Amaranthus hybridus (AH) and their effects on the angiotensin-I-converting enzyme (ACE) and cisplatin-induced malonylaldehyde (MDA) production in an isolated rat kidney homogenate. HPLC confirmed the presence of phenolic compounds in the extracts. Furthermore, all extracts inhibited ACE activity dosedependently; however, the extract from VA exhibited the highest ACE activity while TT exhibited the least. Incubation of the kidney homogenate with 1mM cisplatin caused an increase in MDA production; however, all the extracts inhibited the level of MDA produced. Nevertheless, VA extract exhibited the highest inhibition. These activities of the vegetable extracts could be attributed to their phenolic compositions and may suggest some possible mechanism of the actions. However, VA appeared to be the most potent among the vegetables tested.

Angiotensin-I-Converting Enzyme Inhibitory Activities and In Vivo Antihypertensive Effects of Sardine Protein Hydrolysate.

In our previous study, an antihypertensive protein hydrolysate was prepared from sardine. This study aimed to investigate the composition of sardine protein hydrolysate (SPH) and it's in vivo antihypertensive effect. SPH was separated sequentially with ultrafiltration and size exclusion chromatography. Fractions with high angiotensin-I-converting enzyme (ACE) inhibitory activity were further analyzed with RP-HPLC and amino acids analysis. Then, SPH was individually oral administrated to spontaneously hypertensive rats (SHR) and normotensive wistar kyoto rats (WKY) for 4 wk. After treatment, the systolic blood pressure (SBP), organindex, oxidative status, serum ACE activity, and serum angiotensin-II (ANG-II) of all the rats were determined. According to the separation and analysis results, 3 main fractions with high ACE-inhibitory activity were obtained with different amino acids composition. The animal experiments results showed that SPH could significantly reduce SBP (P < 0.05 or P < 0.01) within 4 h after a single oral administration. After a chronic oral administration, a steady state of SBP in SHR rats was attained. The heart weight index and left ventricular weight index were significantly reduced (P < 0.05) in SPH-treated SHR rats. The malonyldialdehyde (MDA) levels in organs and serum, serum ACE activity, and serum ANG-II concentration in SPH-treated SHR rats were significantly lowered (P < 0.05 or P < 0.01) as compared to their controls. Meanwhile there was no significant effect (P > 0.05) on those parameters in WKY rats. These results indicate that SPH can decrease blood pressure in SHR rats and not in WKY rats.

Soy Pulp Extract Inhibits Angiotensin I-Converting Enzyme (ACE) Activity In Vitro: Evidence for Its Potential Hypertension-Improving Action

ABSTRACTSoy pulp, called “okara” in Japanese, is known as a by-product of the production of bean curd (tofu), and expected to contain a variety of biologically active substances derived from soybean. However, the biological activities of okara ingredients have not yet been fully understood, and the effectiveness of okara as a functional food seems necessary to be further evaluated. Then the effect of okara extract on angiotensin I-converting enzyme (ACE) activity was examined in vitro, and the extract was shown to cause the inhibition of ACE activity in a manner depending on its concentration. Kinetic analysis indicated that this enzyme inhibition was accompanied by an increase in the Km value without any change in Vmax. Further studies suggested that putative inhibitory substances contained in the extract might be heat stable and dialyzable, and recovered mostly in the peptide fraction obtained by a spin-column separation and a high performance liquid chromatography (HPLC) fractionation. Therefore, the extract was speculated to contain small-size peptides responsible for the inhibitory effect of okara extract on ACE activity, and could be expected to improve the hypertensive conditions by reducing the production of hypertensive peptide.

Phenolic Composition and Evaluation of Methanol and Aqueous Extracts of Bitter Gourd (Momordica charantia L) Leaves on Angiotensin-I-Converting Enzyme and Some Pro-oxidant-Induced Lipid Peroxidation In Vitro.

This study sought to assess the effects of bitter gourd leaf extracts (methanol and aqueous) on enzyme linked with hypertension (angiotensin-I-converting enzyme and some pro-oxidants (iron sulfate, sodium nitroprusside, and cisplatin]-induced lipid peroxidation in rat kidney homogenates. Chromatographic analysis of the extract was done using high-performance liquid chromatography-diode array detection. The results revealed that methanol extract (IC50 = 109.63 µg/mL) had significantly (P < .05) higher angiotensin-I converting enzyme inhibitory activity than aqueous extract (IC50 = 182.95 µg/mL). Similarly, methanol extract had significantly (P < .05) higher inhibitory effect on Fe2+- and cisplatin-induced lipid peroxidation than aqueous extract. However, there was no significant (P > .05) difference in the inhibition of sodium nitroprusside-induced lipid peroxidation of both extracts. High-performance liquid chromatography-diode array detection analysis revealed the presence of quercetin, caffeic, gallic, and chlorogenic acids in the leaf. Thus, inhibition of angiotensin-I converting enzyme activity and the antioxidant properties of the extracts could be linked to the presence of phenolic phytochemicals.

Structural Properties of Phycoerythrin from DulsePalmaria palmata

We found that the red alga dulse (Palmaria palmata) contains a lot of proteins, which is mainly composed of phycoerythrin (PE) and the protein hydrolysates showed high angiotensin I converting enzyme (ACE) inhibitory activities. Therefore, we investigated the structure of dulse PE to discuss its structure-function relationship. We prepared the chloroplast DNA and analyzed the nucleotide sequences encoding PE by cDNA cloning method. It was clarified that dulse PE has α- and β-subunits and they are composed by 164 amino acids (MW: 17,638) and 177 amino acids (MW: 18,407), respectively. The dulse PE contained conserved cysteine residues for chromophore attachment site. On the alignment of amino acid sequences of dulse PE with those of other red algal PE, the sequence identities were very high (81–92%). In addition, we purified and crystallized the dulse PE, and its crystal structure was determined at 2.09 A resolution by molecular replacement method. The revealed 3D structure of dulse PE which forms an (αβ)6 hexamer was similar to other red algal PEs. Conversely, it was clarified that the dulse PE proteins are rich in hydrophobic amino acid residues (51.0%), especially aromatic amino acid and proline residues. The data imply that the high ACE inhibitory activity of dulse protein hydrolysates would be caused by the specific amino acid composition and sequence of dulse PE. Practical Applications Dulse is an abundant and underused resource, which contains a lot of phycobiliproteins. Then, the dulse protein hydrolysates strongly inhibited the activity of ACE. Therefore, it has the potential to be an ingredient of functional food.

Aqueous extract from Ficus capensis leaves inhibits key enzymes linked to erectile dysfunction and prevent oxidative stress in rats' penile tissue

ContextFicus capensis Thunb (Moraceae) is a medicinal plant widely grown in tropical and subtropical regions with the leaf decoction commonly taken in traditional folklore as fertility agent in men for ages. AimThis study investigated the effects of aqueous extract from Ficus capensis leaves on angiotensin-I-converting enzyme (ACE), acetylcholinesterase (AChE) and arginase activities in vitro. The antioxidant properties of the extract as typified by the abilities to scavenge radicals [nitric oxide (NO), hydroxyl (OH)], chelate Fe2+ and inhibit Fe2+-induced lipid peroxidation were also assessed. MethodsThe aqueous extract (1:10 w/v) of Ficus capensis leaves was prepared and the ability of the extract to inhibit arginase, angiotensin I –converting enzyme (ACE), acetylcholinesterase (AChE) and antioxidant properties of the extract in rat’s penile tissue in vitro was investigated using various spectrophotometric methods. Phenolic constituent was carried-out using high performance liquid chromatography coupled with diode array detection (HPLC - DAD). ResultsThe extract inhibited ACE (IC50=52.17), AChE (IC50=172.60μg/mL) and arginase (IC50=112.50μg/mL) activities in a dose-dependent pattern. Gallic acid, quercetin, caffeic acid, ellagic acid, rutin and chlorogenic acid were the most abundant phenolic compounds identified in the sample. Furthermore, extract scavenged NO (IC50=0.12μg/mL) and OH (IC50=0.53μg/mL) radicals, chelated Fe2+ (IC50=0.16μg/mL) and inhibited Fe2+ lipid peroxidation (IC50=435.17μg/mL) dose-dependently. ConclusionInhibition of ACE, AChE, arginase, Fe2+-induced lipid peroxidation as well as radical scavenging and Fe2+-chelating abilities could be some of the possible mechanisms by which F. capensis leaves could be used in the treatment/management of erectile dysfunction (ED).

Alligator pepper/Grain of Paradise (Aframomum melegueta) modulates Angiotensin-I converting enzyme activity, lipid profile and oxidative imbalances in a rat model of hypercholesterolemia

Alligator pepper [Aframomum melegueta Roscoe K. (Zingiberaceae)] seeds have been reportedly used in folkloric medicine in the management of hypercholesterolemia and hypertension with limited scientific basis for their action. This study was conducted to characterize the amino acids in Alligator pepper seeds (APS), assess their effects on lipid profile and enzyme linked to blood pressure regulation in hypercholesterolemic rat (rats fed 2% cholesterol diet) model. Free and total amino acids of APS were extracted and their various constituents were analyzed using the amino acid analyzer and ultra-performance liquid chromatography. The effect of dietary inclusion of APS (2–4%) on the lipid profile, angiotensin I-enzyme (ACE) activity and antioxidant status in hypercholesterolemic rats (HCR) for 30days was assessed. The results suggest that APS may modulate blood lipid profile, ameliorate blood pressure, attenuate hepatotoxicity and exert antihypercholesterolemic effect. γ − amino butyric acid (GABA), tyrosine, phenylalanine and tryptophan that were subsequently detected in APS. The observed salutary effects of APS may be attributed to the synergistic or/and additive actions of the amino acids present with other antioxidant phytoconstituents. These findings may therefore provide pharmacological basis for APS use in the treatment of hypercholesterolemia, hyperlipidemia and hypertension.