ACE/angiotensin-converting enzyme

It has been demonstrated that in individuals with hypertension, captopril (SQ 14225) has a similar morbidity and effectiveness to diuretics and beta-blockers. It has been demonstrated that captopril slows the advancement of diabetic nephropathy, but enalapril and lisinopril stop the disease's progression in patients with normoalbuminuric diabetes [4]. The solution contains equimolar ratios of captopril in both its cis and trans states, with the enzyme exclusively choosing the trans form of the compound. The enzyme and its substrate binding base exhibit structural and stereoelectronic complementarity [5].

Captopril, an ACE inhibitor, antagonizes the effect of the RAAS. The RAAS is a homeostatic mechanism for regulating hemodynamics, water and electrolyte balance. During sympathetic stimulation or when renal blood pressure or blood flow is reduced, renin is released from the granular cells of the juxtaglomerular apparatus in the kidneys. In the blood stream, renin cleaves circulating angiotensinogen to ATI, which is subsequently cleaved to ATII by ACE. ATII increases blood pressure using a number of mechanisms. First, it stimulates the secretion of aldosterone from the adrenal cortex. Aldosterone travels to the distal convoluted tubule (DCT) and collecting tubule of nephrons where it increases sodium and water reabsorption by increasing the number of sodium channels and sodium-potassium ATPases on cell membranes. Second, ATII stimulates the secretion of vasopressin (also known as antidiuretic hormone or ADH) from the posterior pituitary gland. ADH stimulates further water reabsorption from the kidneys via insertion of aquaporin-2 channels on the apical surface of cells of the DCT and collecting tubules. Third, ATII increases blood pressure through direct arterial vasoconstriction. Stimulation of the Type 1 ATII receptor on vascular smooth muscle cells leads to a cascade of events resulting in myocyte contraction and vasoconstriction. In addition to these major effects, ATII induces the thirst response via stimulation of hypothalamic neurons. ACE inhibitors inhibit the rapid conversion of ATI to ATII and antagonize RAAS-induced increases in blood pressure. ACE (also known as kininase II) is also involved in the enzymatic deactivation of bradykinin, a vasodilator. Inhibiting the deactivation of bradykinin increases bradykinin levels and may sustain its effects by causing increased vasodilation and decreased blood pressure.

ACE Inhibition Assay[1]
The inhibition of ACE activity by various concentrations of EA and CP as well as their IC50 values were measured using a spectrophotometric method with HHL as substrate as described by Chang et al. with modification. Briefly, a 20 mM sodium borate buffer containing 0.3 M NaCl (pH 8.3) was used for the preparation of EA, CP, ACE, and substrate HHL solutions. The ACE-catalyzed reaction was performed for 30 min at 37 °C in test tubes of the following compositions: 100 μL of EA or CP, 100 μL of ACE solution (40 mU/mL), and 100 μL of HHL (15 mM) solutions (A1); 100 μL of EA or CP solution and 200 μL of borate buffer (A2); 100 μL of borate buffer, 100 μL of ACE solution, and 100 μL of HHL solution (A3); and 300 μL of borate buffer (A4). The enzymatic reaction was stopped by adding 3 mL of alkaline solution of OPA solution (pH 12.0). The absorbance of each reaction was measured at 390 nm using a Beckman DU-640, after incubation for 20 min at 25 °C. Inhibition of ACE by EA or CP was calculated using the following equation: inhibition (%) = [1 – (A1 – A2)/(A3 – A4)] × 100. The IC50 value of ACE activity was calculated by the equation IC50 = (50 – b)/m derived from a linear regression graph of ACE activation, where b is the intercept and m is the slope of the equation.

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Determination of Kinetic Parameters of ACE Inhibition[1]
Kinetic parameters of Vmax and Km values were determined according to the Michaelis–Menten kinetic model. The reaction rate for the formation of l-histidyl-l-leucine from HHL by ACE (40 mU/mL) was determined by the above-mentioned method with EA (0.091 μM) or CP (0.00625 μM) and without EA or CP to get the saturation curves and then plotted against HHL concentrations (0.94, 1.85, 3.75, 7.50, 15 mM). The Lineweaver–Burk plot was derived using the saturation curves to determine the type of inhibition. Kinetic parameters (Km and Vmax) were calculated using MS Excel.

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The inhibitory activity of captopril, a thiol-containing competitive inhibitor of the angiotensin-converting enzyme, ACE, against esterase activity of carbonic anhydrase, CA was investigated. This small molecule, as well as enalapril, was selected in order to represents both thiol and carboxylate, as two well-known metal binding functional groups of metalloprotein inhibitors. Since captopril, has also been observed to inhibit other metalloenzymes such as tyrosinase and metallo-beta lactamase through binding to the catalytic metal ions and regarding CA as a zinc-containing metallo-enzyme, in the current study, we set out to determine whether captopril/enalapril inhibit CA esterase activity of the purified human CA II or not? Then, we revealed the inhibitors' potencies (IC50, Ki and Kdiss values) and also mode of inhibition. Our results also showed that enalapril is more potent CA inhibitor than captopril. Since enalapril represents no sulfhydryl moiety, thus carboxylate group may have a determinant role in inhibiting of CA esterase activity, the conclusion confirmed by molecular docking studies. Additionally, since CA inhibitory potencies of captopril/enalapril were much lower than those of classic sulfonamide drugs, the findings of the current study may explain why these drugs exhibit no effective CA inhibition at the concentrations reached in vivo and also may shed light on the way of generating new class of inhibitors that will discriminately inhibit various CA isoforms[2].

The angiotensin converting enzyme (ACE) inhibitors are widely used in the management of essential hypertension, stable chronic heart failure, myocardial infarction (MI) and diabetic nephropathy. There is an increasing number of new agents to add to the nine ACE inhibitors (benazepril, cilazapril, delapril, fosinopril, lisinopril, pentopril, perindopril, quinapril and ramipril) reviewed in this journal in 1990. The pharmacokinetic properties of five newer ACE inhibitors (trandolapril, moexipril, spirapril, temocapril and imidapril) are reviewed in this update. All of these new agents are characterised by having a carboxyl functional groups and requiring hepatic activation to form pharmacologically active metabolites. They achieve peak plasma concentrations at similar times (t(max)) to those of established agents. Three of these agents (trandolapril, moexipril and imidapril) require dosage reductions in patients with renal impairment. Dosage reductions of moexipril and temocapril are recommended for elderly patients, and dosages of moexipril should be lower in patients who are hepatically impaired. Moexipril should be taken 1 hour before meals, whereas other ACE inhibitors can be taken without regard to meals. The pharmacokinetics of warfarin are not altered by concomitant administration with trandolapril or moexipril. Although imidapril and spirapril have no effect on digoxin pharmacokinetics, the area under the concentration-time curve of imidapril and the peak plasma concentration of the active metabolite imidaprilat are decreased when imidapril is given together with digoxin. Although six ACE inhibitors (captopril, enalapril, fosinopril, lisinopril, quinapril and ramipril) have been approved for use in heart failure by the US Food and Drug Administration, an overview of 32 clinical trials of ACE inhibitors in heart failure showed that no significant heterogeneity in mortality was found among enalapril, ramipril, quinapril, captopril, lisinopril, benazepril, perindopril and cilazapril. Initiation of therapy with captopril, ramipril, and trandolapril at least 3 days after an acute MI resulted in all-cause mortality risk reductions of 18 to 27%. Captopril has been shown to have similar morbidity and mortality benefits to those of diuretics and beta-blockers in hypertensive patients. Captopril has been shown to delay the progression of diabetic nephropathy, and enalapril and lisinopril prevent the development of nephropathy in normoalbuminuric patients with diabetes. ACE inhibitors are generally characterised by flat dose-response curves. Lisinopril is the only ACE inhibitor that exhibits a linear dose-response curve. Despite the fact that most ACE inhibitors are recommended for once-daily administration, only fosinopril, ramipril, and trandolapril have trough-to-peak effect ratios in excess of 50%[5].

[1]. Afrin S, et al. Eritadenine from Edible Mushrooms Inhibits Activity of Angiotensin Converting Enzyme in Vitro. J Agric Food Chem. 2016;64(11):2263-2268.
[2]. Esmaeili S, et al. Captopril/enalapril inhibit promiscuous esterase activity of carbonic anhydrase at micromolar concentrations: An in vitro study. Chem Biol Interact. 2017;265:24-35.
[3]. Li N, et al. Simplified captopril analogues as NDM-1 inhibitors. Bioorg Med Chem Lett. 2014;24(1):386-389.
[4]. Tzakos, A.G., et al., The molecular basis for the selection of captopril cis and trans conformations by angiotensin I converting enzyme. Bioorg Med Chem Lett, 2006. 16(19): p. 5084-7.
[5]. Song, J.C. and C.M. White, Clinical pharmacokinetics and selective pharmacodynamics of new angiotensin converting enzyme inhibitors: an update. Clin Pharmacokinet, 2002. 41(3): p. 207-24.

Captopril is a L-proline derivative in which L-proline is substituted on nitrogen with a (2S)-2-methyl-3-sulfanylpropanoyl group. It is used as an anti-hypertensive ACE inhibitor drug. It has a role as an EC 3.4.15.1 (peptidyl-dipeptidase A) inhibitor and an antihypertensive agent. It is a pyrrolidinemonocarboxylic acid, a N-acylpyrrolidine, an alkanethiol and a L-proline derivative.

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Captopril is a potent, competitive inhibitor of angiotensin-converting enzyme (ACE), the enzyme responsible for the conversion of angiotensin I (ATI) to angiotensin II (ATII). ATII regulates blood pressure and is a key component of the renin-angiotensin-aldosterone system (RAAS). Captopril may be used in the treatment of hypertension.

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Captopril is an Angiotensin Converting Enzyme Inhibitor. The mechanism of action of captopril is as an Angiotensin-converting Enzyme Inhibitor. Captopril is an angiotensin-converting enzyme (ACE) inhibitor used in the therapy of hypertension and heart failure. Captopril is associated with a low rate of transient serum aminotransferase elevations and has been linked to rare instances of acute liver injury. Captopril is a natural product found in Microcystis aeruginosa with data available.

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Captopril is a sulfhydryl-containing analog of proline with antihypertensive activity and potential antineoplastic activity. Captopril competitively inhibits angiotensin converting enzyme (ACE), thereby decreasing levels of angiotensin II, increasing plasma renin activity, and decreasing aldosterone secretion. This agent may also inhibit tumor angiogenesis by inhibiting endothelial cell matrix metalloproteinases (MMPs) and endothelial cell migration. Captopril may also exhibit antineoplastic activity independent of effects on tumor angiogenesis. (NCI04) A potent and specific inhibitor of PEPTIDYL-DIPEPTIDASE A. It blocks the conversion of ANGIOTENSIN I to ANGIOTENSIN II, a vasoconstrictor and important regulator of arterial blood pressure. Captopril acts to suppress the RENIN-ANGIOTENSIN SYSTEM and inhibits pressure responses to exogenous angiotensin.

C9H15NO3S

217.29

217.0772

C, 49.75; H, 6.96; N, 6.45; O, 22.09; S, 14.76

62571-86-2

Captopril hydrochloride;198342-23-3;Captopril-d3;1356383-38-4

44093

Typically exists as white to off-white solids at room temperature

1.3±0.1 g/cm3

427.0±40.0 °C at 760 mmHg

104-108 °C

212.1±27.3 °C

0.0±2.2 mmHg at 25°C

1.551

0.27

96.41

S([H])C([H])([H])[C@@]([H])(C([H])([H])[H])C(N1C([H])([H])C([H])([H])C([H])([H])[C@@]1([H])C(=O)O[H])=O

FAKRSMQSSFJEIM-BQBZGAKWSA-N

InChI=1S/C9H15NO3S/c1-6(5-14)8(11)10-4-2-3-7(10)9(12)13/h6-7,14H,2-5H2,1H3,(H,12,13)/t6-,7-/m0/s1

(2S)-1-[(2S)-2-methyl-3-sulfanylpropanoyl]pyrrolidine-2-carboxylic acid

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Solubility in Formulation 1: ≥ 2.5 mg/mL (11.51 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.5 mg/mL (11.51 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 2.5 mg/mL (11.51 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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Solubility in Formulation 4: 32.5 mg/mL (149.57 mM) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution; with ultrasonication.

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 (Please use freshly prepared in vivo formulations for optimal results.)