Novel Angiotensin I-converting enzyme inhibitory peptides found in a thermolysin-treated elastin with antihypertensive activity

Angiotensin I-converting enzyme (ACE) inhibitory activity was generated from elastin and collagen by hydrolyzing with thermolysin. The IC50 value of 531.6 μg/mL for ACE inhibition by the elastin hydrolysate was five times less than 2885.1 μg/mL by the collagen hydrolysate. We confirmed the antihypertensive activity of the elastin hydrolysate in vivo by feeding spontaneously hypertensive rats (male) on a diet containing 1% of the elastin hydrolysate for 9 weeks. About 4 week later, the systolic blood pressure of the rats in the elastin hydrolysate group had become significantly lower than that of the control group. We identified novel ACE inhibitory peptides, VGHyp, VVPG and VYPGG, in the elastin hydrolysate by using a protein sequencer and quadrupole linear ion trap (QIT)-LC/MS/MS. VYPGG had the highest IC50 value of 244 μM against ACE and may have potential use as a functional food.     

Identification of a potent Angiotensin-I converting enzyme inhibitory peptide from Black cumin seed hydrolysate using orthogonal bioassay-guided fractionations coupled with in silico screening

Black cumin (Nigella sativa) seed protein (BCSP) was individually hydrolyzed with pepsin, trypsin, and α-chymotrypsin. After ultrafiltration, the α-chymotrypsin hydrolysate (< 3 kDa) exhibited the highest ACE inhibitory (ACEI) activity with an IC₅₀ value of 34.4 ± 1.5 μg/mL. This hydrolysate was orthogonally fractionalized using reversed-phase high-performance liquid chromatography (RP-HPLC) and strong cation exchange (SCX) chromatography, and the most active RP-HPLC and SCX fractions (F7 and H4, respectively) were individually screened out by ACEI assay. These two fractions were analyzed with liquid chromatography-tandem mass spectrometry (LC–MS/MS) followed by automated de novo peptide sequencing, and totally 43 ACEI candidate peptides were identified. Three overlapping peptides (VTPVGVPKW, VVTPVGVPKW, and LVLTL) were simultaneously contained in both fractions, and VTPVGVPKW (VW-9) was speculated as to the most potent ACEI peptide based on the in silico analysis. Synthetic VW-9 was used to confirm the identity, and a remarkable IC₅₀ value of VW-9 (1.8 ± 0.09 μM) was determined. Preincubation and inhibition mechanism studies indicated that VW-9 was a true inhibitor as well as a non-competitive inhibitor on ACE, which was further illustrated with the molecular docking simulation. Our study revealed that the application of VW-9 to antihypertensive products is promising.     

Preparation of squid skin collagen hydrolysate as an antihyaluronidase,antityrosinase, and antioxidant agent

A collagen was isolated from squid skin, a processing waste product. The biofunctional activities of enzymatic squid skin collagen hydrolysates were determined to produce a value-added material. Five low-molecular-mass hydrolysate fractions, F1 (>30 kD), F2 (10–30 kD), F3 (3–10 kD), F4 (1–3 kD), and F5 (<1 kD), were manufactured from its enzymatic hydrolysate by ultrafiltration. Fraction F3 had the strongest antihyaluronidase inhibitory activity. Gly, Val, and Pro were major amino acids in F3, while Met, Tyr, and His were minor ones. The molecular mass of F3 was in the range of 3.4 to 10 kD. F3 exhibited copper chelating ability in a concentration-dependent manner. The ferrous chelating ability of F3 was almost 50% at 200 µg/mL. F3 also inhibited tyrosinase activity by 39.65% at 1 mg/mL. Furthermore, F3 had stronger hydroxyl radical scavenging activity (IC₅₀ = 149.94 µg/mL) than ascorbic acid (IC₅₀ = 212.94 µg/mL). Therefore, the squid collagen hydrolysate can be utilized as a nutraceutical or cosmeceutical agent.     

Identification and molecular docking of novel ACE inhibitory peptides from protein hydrolysates of shrimp waste

The effect of enzymatic hydrolysis by Savinase on the interfacial properties and antihypertensive activity of shrimp waste proteins was evaluated. The physicochemical characterization, interfacial tension, and surface characteristics of shrimp waste protein hydrolysates (SWPH) using different enzyme/substrate (E/S) (SWPH₅ (SWPH using E/S = 5), SWPH₁₅ (SWPH using E/S = 15), and SWPH₄₀ (SWPH using E/S = 40)) were also studied. SWPH₅, SWPH₁₅, and SWPH₄₀ had an isoelectric pH around 2.07, 2.17, and 2.54 respectively. SWPH₅ exhibited the lowest interfacial tension (68.96 mN/m) followed by SWPH₁₅ (69.36 mN/m) and SWPH₄₀ (70.29 mN/m). The in vitro ACE inhibitory activity of shrimp waste protein hydrolysates showed that the most active hydrolysate was obtained using an enzyme/substrate of 15 U/mg (SWPH₁₅). SWPH₁₅ had a lower IC₅₀ value (2.17 mg/mL) than that of SWPH₅ and SWPH₄₀ (3.65 and 5.7 mg/mL, respectively). This hydrolysate was then purified and characterized. Fraction F1 separated by Sephadex G25 column which presents the best ACE inhibition activity was then separated by reversed‐phase high performance liquid chromatography. Four ACE inhibitory peptides were identified and their molecular masses and amino acid sequences were determined using ESI–MS and ESI–MS/MS, respectively. The structures of the most potent peptides were SSSKAKKMP, HGEGGRSTHE, WLGHGGRPDHE, and WRMDIDGDIMISEQEAHQR. The structural modeling of anti‐ACE peptides from shrimp waste through docking simulations results showed that these peptides bound to ACE with high affinity.     

Purification and characterization of angiotensin I-converting enzyme inhibitory peptide from enzymatic hydrolysates of Styela clava flesh tissue

Angiotensin I-converting enzyme (ACE) inhibitory peptide was isolated from the Styela clava flesh tissue. Nine proteases (Protamex, Kojizyme, Neutrase, Flavourzyme, Alcalase, pepsin, trypsin, α-chymotrypsin and papain) were used, and their respective enzymatic hydrolysates and an aqueous extract were screened to evaluate their potential ACE inhibitory activity. Among all of the test samples, Protamex hydrolysate possessed the highest ACE inhibitory activity, and the Protamex hydrolysate of flesh tissue showed relatively higher ACE inhibitory activity compared with the Protamex hydrolysate of tunic tissue. We attempted to isolate ACE inhibitory peptide from the Protamex hydrolysate of S. clava flesh tissue using ultrafiltration, gel filtration on a Sephadex G-25 column and high performance liquid chromatography (HPLC) on an ODS column. The purified ACE inhibitory peptide exhibited an IC₅₀ value of 37.1 μM and was identified as non-competitive inhibitor of ACE. Amino acid sequence of the peptide was identified as Ala-His-Ile-Ile-Ile, with a molecular weight 565.3 Da. The results of this study suggested that the peptides derived from enzymes-assisted extracts of S. clava would be useful new antihypertension compounds in functional food resource.     

ACE inhibitory,hypotensive and antioxidant peptide fractions from Mucuna pruriens proteins

Hydrolysates and peptide fractions obtained from Mucuna pruriens protein concentrate were studied for their angiotensin converting enzyme (ACE) inhibitory, hypotensive and antioxidant activities. The hydrolysate obtained by pepsin–pancreatin (HPP) was the most active with an ACE IC₅₀ value of 19.5 μg/mL, a Trolox equivalent antioxidant capacity (TEAC) value of 102.8 mM/mg and a ferric reducing power (FRP) IC₅₀ of 67.2 μg/mL. At a dose of 5 mg/kg HPP decrease systolic (32.2%) and diastolic (37%) blood pressure in rats more pronounced than Captopril. The peptide fraction <1 kDa from HPP was the most active with an ACE inhibitory of 10.2 μg/mL (IC₅₀), a TEAC value of 709.8 mM/mg and a FRP IC₅₀ of 54.9 μg/mL. These results indicate that the hydrolysates and peptide fractions of M. pruriens would be used as nutraceuticals ingredients for preventing and providing therapy against hypertension and diseases related to oxidative damage.     

Preparation and characterization of novel bioactive peptides responsible for angiotensin I‐converting enzyme inhibition from wheat germ

Reported is the preparation of wheat germ (WG) hydrolyzate with potent angiotensin I‐converting enzyme (ACE) inhibitory activity, and the characterization of peptides responsible for ACE inhibition. Successful hydrolyzate with the most potent ACE inhibitory activity was obtained by 0.5 wt.%–8 h Bacillus licheniformis alkaline protease hydrolysis after 3.0 wt.%–3 h α‐amylase treatment of defatted WG (IC₅₀; 0.37 mg protein ml⁻¹). The activity of WG hydrolyzate was markedly increased by ODS and subsequent AG50W purifications (IC₅₀; 0.018 mg protein ml⁻¹). As a result of isolations by high performance liquid chromatographies, 16 peptides with the IC₅₀ value of less than 20 μm , composed of 2–7 amino acid residues were identified from the WG hydrolyzate. Judging from the high content (260 mg in 100 g of AG50W fraction) and powerful ACE inhibitory activity (IC₅₀; 0.48 μm ), Ile‐Val‐Tyr was identified as a main contributor to the ACE inhibition of the hydrolyzate. Copyright © 1999 European Peptide Society and John Wiley & Sons, Ltd.     

Purification and characterization of angiotensin I converting enzyme inhibitory peptides from the rotifer, Brachionus rotundiformis

Angiotensin I converting enzyme (ACE) inhibitory peptide was isolated from the marine rotifer, Brachionus rotundiformis. ACE inhibitory peptides were separated from rotifer hydrolysate prepared by Alcalase, α-chymotrypsin, Neutrase, papain, and trypsin. The Alcalase hydrolysate had the highest ACE inhibitory activity compared to the other hydrolysates. The IC₅₀ value of Alcalase hydrolysate for ACE inhibitory activity was 0.63 mg/ml. We attempted to isolate ACE inhibitory peptides from Alcalase prepared rotifer hydrolysate using gel filtration on a Sephadex G-25 column and high performance liquid chromatography on an ODS column. The IC₅₀ value of purified ACE inhibitory peptide was 9.64 μM, and Lineweaver–Burk plots suggest that the peptide purified from rotifer protein acts as a competitive inhibitor against ACE. Amino acid sequence of the peptide was identified as Asp-Asp-Thr-Gly-His-Asp-Phe-Glu-Asp-Thr-Gly-Glu-Ala-Met, with a molecular weight 1538 Da. The results of this study suggest that peptides derived from rotifers may be beneficial as anti-hypertension compounds in functional foods resource.     

In Vitro Anticancer Activity of Staphyloxanthin Pigment Extracted from <Emphasis Type="Italic">Staphylococcus gallinarum</Emphasis> KX912244, a Gut Microbe of <Emphasis Type="Italic">Bombyx mori</Emphasis>

The present study reports the in vitro biological nature of the pigment produced by Staphylococcus gallinarum KX912244, isolated as the gut microflora bacterium of the insect Bombyx mori. The purified pigment was characterized as Staphyloxanthin based on bio-physical characterization techniques like Fourier transform infrared spectroscopy, high performance liquid chromatography, Proton nuclear magnetic resonance spectroscopy (¹H NMR), Liquid chromatography-Mass spectroscopy and Gas chromatography-Mass spectroscopy. The Staphyloxanthin pigment presented considerable biological properties including in vitro antimicrobial activity against pathogens Staphylococcus aureus, Escherichia coli and Candida albicans; in vitro antioxidant activity by % DPPH free radical scavenging activity showing IC₅₀ value of 54.22 µg/mL; DNA damage protection activity against reactive oxygen species and anticancer activity evaluated by cytotoxicity assay against 4 different cancer cell lines like the Dalton’s lymphoma ascites with IC₅₀ value 6.20?±?0.02 µg/mL, Ehrlich ascites carcinoma having IC₅₀ value 6.48?±?0.15 µg/mL, Adenocarcinomic human alveolar basal epithelial cells (A549 Lung carcinoma) bearing IC₅₀ value 7.23?±?0.11 µg/mL and Mus mucus skin melanoma (B16F10) showing IC₅₀ value 6.58?±?0.38 µg/mL and less cytotoxicity towards non-cancerous human fibroblast cell lines (NIH3T3) with IC₅₀ value of 52.24 µg/mL. The present study results suggest that Staphyloxanthin acts as a potential therapeutic agent especially due to its anticancer property.     

Purification and molecular docking study of angiotensin I-converting enzyme (ACE) inhibitory peptides from hydrolysates of marine sponge Stylotella aurantium

Angioteinsin I-converting enzyme (ACE) inhibitory peptide was isolated from marine sponge (Stylotella aurantium) hydrolysate prepared by various hydrolysis enzymes. The peptic hydrolysate exhibited highest ACE inhibitory activity among them and was fractionated into three ranges of molecular weight. The below 5 kDa fraction showed the highest ACE inhibitory activity and was used for subsequent purification steps. The amino acid sequences of the purified peptides were identified to be Tyr-Arg (337.2 Da), and Ile-Arg (287.2 Da). The purified peptides from marine sponge had an IC₅₀ value of 237.2 μM and 306.4 μM, respectively. The molecular docking study revealed that ACE inhibitory activity of the purified peptides was mainly attributed to the hydrogen bond interactions and Pi interaction between the dipeptides and ACE. The results suggest that marine sponge, S. aurantium would be an attractive raw material for the manufacture of anti-hypertensive nutraceutical ingredients.     

LC/MS/MS Phenolic Profile,Antioxidant Capacity,Angiotensin-Converting Enzyme (ACE) and Glutathione S Transferase (GST) Inhibitory Properties of Ultrasound-Assisted Propolis Extracts

Resinous beehive product propolis has many biological activities. It contains various aromatic substances that have great differences in their chemical composition depending on the natural flora. Thus, chemical characterization and biological properties of propolis samples is an important subject for the pharmaceutical industry. In this study, the propolis samples collected from three cities in Turkey were prepared as methanol (MEP), ethanol (EEP), chloroform (ChlEP), hexane (HxEP), and ethyl acetate (EAEP) extracts using an ultrasonic assisted technique. The antioxidant capacities of the samples were evaluated by free radical scavenging activity (DPPH), cation radical scavenging activity (ABTS), and reducing activity (CUPRAC) and (FRAP). The strongest biological activities were detected in ethanol and methanol extracts. Enzyme inhibition of the propolis samples were determined against the human glutathione S-transferase (GST) and angiotensin converting enzyme (ACE). IC₅₀ values of MEP1, MEP2, and MEP3 samples against the ACE were found as 13.9 μg/mL, 14.8 μg/mL, and 12.8 μg/mL, while against the GST IC₅₀ values of MEP1, MEP2, and MEP3 samples were as 5.92 μg/mL, 9.49 μg/mL, and 5.72 μg/mL. To know the possible causes of the biological test results advanced LC/MS/MS method was applied. trans-ferulic acid, kaempferol, and chrysin were found as the most abundant phenolic compounds in each sample. The propolis extracts obtained using the proper solvent have a good potential to be used in pharmaceuticals to treat the diseases related to oxidative damage, hypertension, and inflammation. Finally, the interactions between chrysin, trans-ferulic acid and kaempferol molecules with ACE and GST receptors were analyzed using molecular docking study. Selected molecules interact with active residues by binding to the active site of the receptors.     

Profiling the phyto-constituents of Punica granatum fruits peel extract and accessing its in-vitro antioxidant,anti-diabetic,anti-obesity,and angiotensin-converting enzyme inhibitory properties

This context was investigated to assess the in vitro antioxidant, anti-diabetic, anti-obesity, and angiotensin-converting enzyme (ACE) inhibition traits of Punica granatum fruits peel extract. Initially, among various extracts tested, aqueous and ethanolic peel extracts depicted the presence of diverse phytoconstituents. In vitro antioxidative properties of peel extracts were determined using standard methodologies. Results showed that aqueous and ethanolic extracts had IC₅₀ values of 471.7 and 509.16 μg/mL, respectively in terms of 1,1,diphenyl 2,2,picrylhydrazyl scavenging. Likewise, IC₅₀ values of aqueous and ethanol extract were obtained as 488.76 and 478.47 μg/mL towards the degradation of hydrogen peroxide. The ethanolic extract exhibited the highest inhibition of α-glucosidase by showing activity of 53.34 ± 2.0 to 15.18 ± 1.4 U/L in a dose dependent manner (100–1000 µg/mL). Ethanolic extract was reported as the most active inhibitor of lipase with an IC₅₀ value of 603.50 µg/mL. Ethanolic extract showed increased inhibition of ACE in a concentration dependent manner (100–1000 µg/mL) with IC₅₀ value of 519.45 µg/mL. Fourier transform-infrared spectrum revealed the availability of various functional groups in the ethanolic extract of peel. Gas chromatography-mass spectrometry chromatogram of peel extract illustrated 23 diversified chemical constituents including 1,2,3,4-butanetetrol, Dimethyl sulfone, 9-octadecenamide, and Pentadecanoic acid as predominant compounds. In summary, P. granatum fruits peel extract revealed promising antioxidant, anti-diabetic, anti-obesity, and anti-hypertensive properties.     

Synthesis and molecular docking study of some novel 2,3-disubstituted quinazolin-4(3H)-one derivatives as potent inhibitors of urease

A new series of 2,3-disubstituted quinazolin-4(3H)-one compounds including oxadiazole and furan rings was synthesized. Their inhibitory activities on urease were assessed in vitro. All newly synthesized compounds exhibited potent urease inhibitory activity in the range of IC₅₀ = 1.55 ± 0.07–2.65 ± 0.08 µg/mL, when compared with the standard urease inhibitors such as thiourea (IC₅₀ = 15.08 ± 0.71 µg/mL) and acetohydroxamic acid (IC₅₀ = 21.05 ± 0.96 µg/mL). 2,3-Disubstituted quinazolin-4(3H)-one derivatives containing furan ring (3a-e) were found to be the most active inhibitors when compared with the compounds 2a-e bearing oxadiazole ring. Compound 3a, bearing 4-chloro group on phenyl ring, was found as the most effective inhibitor of urease with the IC₅₀ value of 1.55 ± 0.11 µg/mL. The molecular docking studies of the newly synthesized compounds were performed to identify the probable binding modes in the active site of the Jack bean urease (JBU) enzymes.     

Antioxidant and angiotensin-converting enzyme (ACE) inhibitory activity of thymosin alpha-1 (Thα1) peptide

In this research, the antioxidant property of thymosin alpha-1 (Thα1) peptide was investigated through various antioxidant methods. Thα1 showed 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (IC₅₀ = 20 µM) and its 2,2-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) scavenging reached 45.33% at 80 µM (IC₅₀ = 85 µM). In addition, hydroxyl and superoxide radical scavenging of Thα1 peptide exhibited a concentration-depended manner. The IC₅₀ values of hydroxyl and superoxide radical scavenging were estimated to be 82 µM and 20 µM, respectively. The effect of Thα1 on eliminating superoxide radicals was higher (62.23%) than other antioxidant assays. Moreover, the antioxidant activity of Thα1 peptide was evaluated by measuring cellular reactive oxygen species (ROS). Results indicated that Thα1 decreased the generation of ROS level in 1321 N1 human neural asterocytoma cells. The inhibitory effect of Thα1 on angiotensin-converting enzyme (ACE) was determined. The kinetic parameters (K_m and V_max) and the inhibition pattern were examined. Based on the Lineweaver-Burk plot, Thα1 displayed a mixed inhibition pattern. The IC₅₀ and K_i values of Thα1 were 0.8 µM and 3.33 µM, respectively. Molecular modeling suggested that Thα1 binds to ACE-domains with higher affinity binding to N-domain with the binding energy of −22.87 kcal/mol. Molecular docking indicated that Thα1 interacted with ACE enzyme (N- and C-domains) due to electrostatic, hydrophobic, and hydrogen forces. Our findings suggested that Thα1 possess a multifunctional peptide with dual antioxidant and ACE-inhibitory properties. Further researches are needed to investigate the antioxidant and anti-hypertensive effect of Thα1 both in vitro and in vivo.     

Synthesis,in vitro urease inhibition and molecular docking studies of some novel quinazolin-4(3H)-one derivatives containing triazole,thiadiazole and thiosemicarbazide functionalities

A new series of quinazolinone derivatives containing triazole, thiadiazole, thiosemicarbazide functionalities was synthesized and then screened for their in vitro urease inhibition properties. Most of the compounds showed excellent activity with IC₅₀ values ranging between 1.88 ± 0.17 and 6.42 ± 0.23 µg/mL, compared to that of thiourea (IC₅₀ = 15.06 ± 0.68) and acetohydroxamic acid (IC₅₀ = 21.03 ± 0.94), as reference inhibitors. Among the synthesized molecules, compounds 5c, 5e and 5a showed the best inhibitory effect against urease enzyme with IC₅₀ values of 1.88 ± 0.17 µg/mL, 1.90 ± 0.10 and 1.96 ± 0.07 µg/mL, respectively. Moreover in order to give better understanding of the inhibitory activity of synthesized compounds, molecular docking studies were applied at the target sites of jack bean urease enzyme (JBU). Their binding poses and energy calculations were analyzed using induced fit docking (IFD) and prime-MMGBSA tool. Binding poses of studied compounds were determined using induced fit docking (IFD) algorithms.     

Tyrosinase inhibitory effects of Vinca major and its secondary metabolites: Enzyme kinetics and in silico inhibition model of the metabolites validated by pharmacophore modelling

In the present study, we aimed to identify the tyrosinase enzyme inhibitory potential of Vinca major L. extract and its secondary metabolites. The extract possessed remarkable tyrosinase enzyme inhibitory effect with IC₅₀ value of 20.39 ± 0.44 µg/mL compared to the positive control, kojic acid (IC₅₀ 8.56 ± 0.17 µg/mL). Compounds 1 and 5 were the most potent isolates with IC₅₀ values of 32.41 ± 0.99 and 31.34 ± 0.75 µM, they were more potent than kojic acid (IC₅₀: 60.25 ± 0.54 µM). Compound 2 also exhibited remarkable tyrosinase inhibition with an IC₅₀ value of 64.51 ± 1.29 µM. An enzyme kinetics analysis revealed that 1 was a mixed-type, 2 and 5 were noncompetitive inhibitors. Using molecular docking, we predicted binding affinity and interactions of the compounds, which were in good alignment with a pharmacophore hypothesis generated out of a number of known tyrosinase inhibitors. The modelling studies underlined crucial interactions with the copper ions and residues around them such as Asn260, His263, and Met280.     

1H Quantitative NMR analyses of β-asarone and related compounds for quality control of Acorus rhizome herbal drugs in terms of the effects of their constituents on in vitro acetylcholine esterase activity

We used quantitative nuclear magnetic resonance analyses to measure the contents of major constituents of Acorus rhizome materials used as herbal drugs. The inhibitory effects of crude n-hexane extracts and their individual constituents on in vitro acetylcholine esterase activity were evaluated. The crude extracts had unexpectedly weak inhibitory effects (46–64% inhibition at 1.0 mg/mL), despite the high content (46–64%) of β-asarone, which independently had a potent effect (IC₅₀ 2.9 µM [0.61 µg/mL]). Further investigation revealed participation of eudesmin A, a lignan constituent, in the suppression of the inhibitory effect of β-asarone.     

Phytochemical Fingerprints and Bioactivities of Ripe Disseminules (Fruit-Seeds) of Seventeen Gundelia (Kenger-Kereng Dikeni) Species from Anatolia with Chemometric Approach

Gundelia species are known as “Kenger-kereng dikeni” in Anatolia, and their aerial parts are consumed as food. Also, roots and seeds (disseminules) of the Gundelia species are used to prepare gum and coffee. The chemical contents of ethanol and hexane extracts of disseminules of 17 Gundelia species, 13 of them are endemic, were studied using LC/MS/MS and GC/MS. Additionally, their antioxidant potential and enzyme inhibitory capacity against acetyl- and butyryl-cholinesterase, urease, and tyrosinase were determined. The unsaturated fatty acid ratios of Gundelia species were higher than their saturated fatty acid ratio. The highest sum of oleic and linoleic acid was detected in G. tournefortii var. tenuisecta (70.42 %). β-Sitosterol, α-amyrin, 3-acetyllupeol were identified in 17 Gundelia species by GC/MS, while chlorogenic acid and luteolin by LC/MS/MS as major compounds. The ethanol and hexane extracts of G. siirtica, G. rosea, and G. mesopotamica indicated good cholinesterase inhibitory activity. Among all species, ethanol extract of G. colemerikensis exhibited the best activity in ABTS (IC₅₀: 32.30±0.98 μg/mL), DPPH (IC₅₀: 59.91±0.89 μg/mL), and CUPRAC (A_0.5: 57.41±1.03 μg/mL) assays. Ethanol extract of G. colemerikensis also displayed the highest inhibitory activity against butyrylcholinesterase (51.14±0.25 % at 200 μg/mL), urease (51.71±1.75 % at 200 μg/mL), and tyrosinase (39.50±0.85 % at 200 μg/mL) enzymes. According to the chemometric analysis of fatty acids, four groups were observed. Therefore, it is suggested that G. colemerikensis can be used in the pharmaceutical, food, and cosmetic industries due to its antioxidant and enzyme inhibition properties.     

Effects of Angiotensin I-Converting Enzyme Inhibitory Substances Derived from Indonesian Dried-salted fish on Blood Pressure of Rats

Indonesian dried-salted fish (DSF) was produced from skipjack tuna by soaking the flesh in 15% NaCl (DSF I) or 25% NaCl (DSF II). The DSFs were then hydrolyzed by trypsin, chymotrypsin, Pronase E, and pepsin. Angiotensin I-converting enzyme (ACE) inhibitory activity was measured. The pepsin digest showed the highest inhibitory activity (IC₅₀; 0.63 mg protein/ml). DSF II hydrolysate had higher inhibitory activity than that in DSF I. A three-month storage period of DSF gave higher ACE-inhibitory activity than that of 6 months. An oral administration of pepsin hydrolysate significantly decreased the blood pressure of rats. From the purification steps, at least 4 inhibitor peptides were found. The amino acid sequences of the peptides were Val-Ala-Trp-Lys-Leu, Trp-Ser-Lys-Val-Val-Leu, Ser-Lys-Val-Pro-Pro, and Cys-Trp-Leu-Pro-Val-Tyr, with an IC₅₀ value of 31.97, 156.28, 74.22, and 22.20 μM, respectively.     

Potent ACE inhibitors from 5-hydroxy indanone derivatives

A novel triazole derivatives(±)-2-(hydroxymethyl)-7,8-dihydro-1H-indeno[5,4-b]furan-6(2H)-one (12a–j) were designed and synthesized by the reaction between racemic azide and terminal acetylenes under click chemistry reaction conditions followed by biological evaluation as angiotensin converting enzyme (ACE) inhibitors. β-Amino alcohol derivatives of 1-indanone (15a–l) were synthesized from 5-hydroxy indanone, it was reacted with epichlorohydrin and followed by oxirane ring opening with various piperazine derivatives. Among the newly synthesized compounds 12b (IC₅₀: 1.388024 µM), 12g (IC₅₀: 1.220696 µM), 12j (IC₅₀: 1.312428 µM) and 15k (IC₅₀: 1.349671 µM) and 15l (IC₅₀: 1.330764 µM) emerged as most active non-carboxylic acid ACE inhibitors with minimal toxicity comparable to clinical drug Lisinopril.