Novel renin inhibitors containing derivatives of N-alkylleucyl-β-hydroxy-γ-amino acids

Article abstract of DOI:10.1002/psc.2846

In search for new drugs lowering arterial blood pressure, which could be applied in anti-hypertensive therapy, research concerning agents blocking of renin-angiotensin-aldosteron system has been conducted. Despite many years of research conducted at many research centers around the world, aliskiren is the only one renin inhibitor, which is used up to now. Four novel potential renin inhibitors, having structure based on the peptide fragment 8-13 of human angiotensinogen, a natural substrate for renin, were designed and synthesized. All these inhibitors contain unnatural moieties that are derivatives of N-methylleucyl-β-hydroxy-γ-amino acids at the P₂-P₁' position: 4-[N-(N-methylleucyl)-amino]-3-hydroxy-7-(3-nitroguanidino)-heptanoic acid (AHGHA), 4-[N-(N-methylleucyl)-amino]-3-hydroxy-5-phenyl-pentanoic acid (AHPPA) or 4-[N-(N-methylleucyl)-amino]-8-benzyloxycarbonylamino-3-hydroxyoctanoic acid (AAHOA). The previously listed synthetic β-hydroxy-γ-amino acids constitute pseudodipeptidic units that correspond to the P₁-P₁' position of the inhibitor molecule. An unnatural amino acid, 4-methoxyphenylalanin (Phe(4-OMe)), was introduced at the P₃ position of the obtained compounds. Three of these compounds contain isoamylamide of 6-aminohexanoic acid (ε-Ahx-Iaa) at the P₂'-P₃' position. The proposed modifications of the selected human angiotensinogen fragment are intended to increase bioactivity, bioavailability, and stability of the inhibitor molecule in body fluids and tissues. The inhibitor Boc-Phe(4-OMe)-MeLeu-AHGHA-OEt was obtained in the form of an ethyl ester. The hydrophobicity coefficient, expressed as log P varied between 3.95 and 8.17. In vitro renin inhibitory activity of all obtained compounds was contained within the range 10^-6-10^-9 M. The compound Boc-Phe(4-OMe)-MeLeu-AHPPA-Ahx-Iaa proved to be the most active (IC₅₀ = 1.05 × 10^-9 M). The compounds Boc-Phe(4-OMe)-MeLeu-AHGHA-Ahx-Iaa and Boc-Phe(4-OMe)-MeLeu-AHPPA-Ahx-Iaa are resistant to chymotrypsin.

Full text of DOI:10.1002/psc.2846

Research Article
Received: 24 August 2015
Revised: 17 November 2015
Accepted: 22 November 2015
Published online in Wiley Online Library
(wileyonlinelibrary.com) DOI 10.1002/psc.2846
Novel renin inhibitors containing derivatives of
N-alkylleucyl-β-hydroxy-γ-amino acids
Iwona Winiecka,* Paweł Jaworski, Aleksander Paweł Mazurek,
Dorota Marszałek, Anna Goldnik and Daniel Sokulski
In search for new drugs lowering arterial blood pressure, which could be applied in anti-hypertensive therapy, research
concerning agents blocking of renin-angiotensin-aldosteron system has been conducted. Despite many years of research
conducted at many research centers around the world, aliskiren is the only one renin inhibitor, which is used up to now.
Four novel potential renin inhibitors, having structure based on the peptide fragment 8–13 of human angiotensinogen, a
natural substrate for renin, were designed and synthesized. All these inhibitors contain unnatural moieties that are derivatives
of N-methylleucyl-β-hydroxy-γ-amino acids at the P2-P1’ position: 4-[N-(N-methylleucyl)-amino]-3-hydroxy-7-(3-nitroguanidino)-
heptanoic acid (AHGHA), 4-[N-(N-methylleucyl)-amino]-3-hydroxy-5-phenyl-pentanoic acid (AHPPA) or 4-[N-(N-methylleucyl)-
amino]-8-benzyloxycarbonylamino-3-hydroxyoctanoic acid (AAHOA). The previously listed synthetic β-hydroxy-γ-amino acids
constitute pseudodipeptidic units that correspond to the P1-P1’ position of the inhibitor molecule. An unnatural amino acid,
4-methoxyphenylalanin (Phe(4-OMe)), was introduced at the P3 position of the obtained compounds. Three of these
compounds contain isoamylamide of 6-aminohexanoic acid (ε-Ahx-Iaa) at the P2’-P3’ position. The proposed modifications
of the selected human angiotensinogen fragment are intended to increase bioactivity, bioavailability, and stability of the
inhibitor molecule in body fluids and tissues. The inhibitor Boc-Phe(4-OMe)-MeLeu-AHGHA-OEt was obtained in the form
of an ethyl ester. The hydrophobicity coefficient, expressed as log P varied between 3.95 and 8.17. In vitro renin inhibitory
activity of all obtained compounds was contained within the range 10À6-10À9 M. The compound Boc-Phe(4-OMe)-MeLeu-AHPPA-Ahx-
Iaa proved to be the most active (IC50 =1.05×10À9 M). The compounds Boc-Phe(4-OMe)-MeLeu-AHGHA-Ahx-Iaa and Boc-Phe(4-OMe)-
MeLeu-AHPPA-Ahx-Iaa are resistant to chymotrypsin. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.
Keywords: hypertension treatment; renin inhibitors; amino acids; pseudodipeptidic unit
unrelated to its hypotensive activity [9–11]. Adverse reactions and
contraindications related to aliskiren are scarce. It must not be used
Introduction
in pregnant women or in patients with renal artery stenosis. The
Arterial hypertension is the major risk factor of cardiovascular
level of potassium in blood serum increases as a result of therapy
diseases, such as cerebral stroke, myocardial infarction, cardiac in-
with this drug. Therefore, it is necessary to continue development
sufficiency, or renal insufficiency. The most recent guidelines for
of this class of drugs. Poor bioavailability and instability of the mole-
handling arterial hypertension, published by European and
cule under physiological conditions are major obstacles that are
American hypertensiology and cardiology societies, are classifying
preventing renin inhibitors from broader introduction into medicinal
blockers of the renin-angiotensin system within the group of basic
practice. Therefore, new-generation inhibitors that do not contain an
hypotensive drugs [1–4]. The angiotensin converting enzyme in-
unstable peptide linkage (-CONH-), which is susceptible to enzymatic
hibitors and angiotensin II receptor blockers specified in these
degradation, were designed in order to overcome the aforemen-
reports are also first-choice drugs also in diabetic patients with
tioned problems. Non-peptidic renin inhibitors include aliskiren and
cardiovascular and renal complications [5,6]. Another promising
strategy for blocking the renin-angiotensin-cascade at an early
stage involves inhibition of renin. This mechanism prevents forma-
a novel class of inhibitors that are piperidine derivatives [12–14]. In
our opinion, it is important that the inhibitors would have ability to
form hydrogen bonds with the -CONH- moiety, which could result
tion of angiotensin I from angiotensinogen that is a renin substrate.
in increased inhibitory activity. Therefore, molecules of the designed
An indirect consequence of renin inhibition is prevention of
compounds contain -CONH- moieties that, however, are not classic
converting of inactive angiotensin I to angiotensin II, an octapeptide
having hypertensive activity. Until now, only one renin inhibitor,
aliskiren, is available on the pharmaceutical market. It is marketed
peptide bonds obtained by linking two α-amino acids. In the
compounds synthesized by us, we combined unnatural
since 2007 [7]. First observations concerning efficacy and safety
profile of aliskiren, after just several years of use, are satisfactory.
*
Correspondence to: Iwona Winiecka, Department of Drug Chemistry, Medical
University of Warsaw, Banacha 1, 02 – 097 Warsaw, Poland, E-mail: iwona.
winiecka@wum.edu.pl
Despite low bioavailability, not exceeding 2.7%, aliskiren effectively
lowers blood pressure [8]. It is well tolerated by majority of patients.
Because hepatobiliary elimination (90% of aliskiren is excreted in
bile), it may be used in hypertensive patients with concomitant
kidney diseases. Aliskiren has certain nephroprotective potential,
Department of Drug Chemistry, Medical University of Warsaw, Banacha 1, 02 –
097, Warsaw, Poland
J. Pept. Sci. 2016; 22: 106–115
Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.

NOVEL RENIN INHIBITORS CONTAINING AMINO ACIDS DERIVATIVES
derivatives of amino acids with pseudodipeptides. Such
modified molecules that contain -CONH- moieties should be
completely or at least significantly protected against enzymatic deg-
radation. Results of concurrent studies on activity/structure relation-
ship of renin inhibitors performed at various research centers
suggest a great importance of hydrophobic properties of the inhibi-
tors. The level of hydrophobicity has a decisive impact on biological
activity and bioavailability of these compounds. Four novel com-
pounds were designed and synthesized in order to determine the
impact of interactions between the inhibitor’s molecule and the hy-
drophobic active site of renin on their inhibitory activity, as shown
in Figures 1–4 . The compounds were designed by modifying a moi-
ety of angiotensinogen, that is, the natural renin substrate as it is
depicted in Figure 5. Currently, it is known that the hydrophobic
pocket S3–S1 is the key binding site for hydrophobic moieties of renin
blockers. Hydrophobic interactions with the S4 and S2’–S3’ pockets
[15] are also important for their inhibitory activity. Recent discovery
of sub-pockets within the S3 and S1 sites [16,17] that could react with
hydrophilic and polar moieties opens new possibility of designing
inhibitors that are significantly modified at the P1 position. By facili-
tating formation of additional hydrogen bonds, the modifications
could lead to enhanced enzyme-inhibitor interactions as shown in
Figure 6. Taking into consideration these discoveries and continuing
our prior studies, we designed novel renin inhibitory molecules that
contained hydrophobic moieties at all P3–P2–P1–P1’–P2’–P3’ sites.
Figure 2. 6-{N-[4-[N-[N-/N-(t-butoxycarbonyl)-4-methoxyphenylalanyl/-N-
methylleucyl]-amino]-7-(3-nitroguanidino)-3-hydroxyheptanoyl]-amino}-
hexanoic acid isoamylamide Boc-Phe(4-OMe)-MeLeu-AHGHAAhx-Iaa 11.
230 to 400 mesh) was used to separate and purify all synthesized
compounds. Thin Layer Chromatography (TLC) was carried out on
0.25-mm thickness silica gel plates (Merck, silica gel 60 F254). The sol-
vent systems used in TLC and CC were CHCl3/MeOH and
hexane/EtOAc in various ratios. The spots were visualized with 0.3%
ninhydrin in EtOH/AcOH (97: 3, v/v). Perkin–Elmer Microanalyser was
used to carry out elemental analyses. Böetius apparatus was used to
determine melting points. Bruker DM 300-MHz Avance 300-WB spec-
1
trometer was applied to record H-NMR. Chemical shifts were mea-
sured relative to tetramethylsilane (TMS) as δ units (ppm). Optical
rotations were measured at the Na-D line with use of AP-300 (Atago)
polarimeter in a 5-cm polarimeter cell. HPLC analyses of purity and ac-
tivity of synthesized inhibitors were performed on a Shimadzu appara-
tus equipped with a LC-10AT pump, UV–vis SPD-10A detector and
Chromax 2010 recorder. The peaks were recorded at the wavelength
of 213 nm. The separation was carried out in the reverse phase system
(Wide Pore C8, Symmetry C18) with various mobile phases.
Experimental
Chemistry
The structures of inhibitors considered in the present work are
shown in Figures 1–4. The inhibitors 7, 11, 18, 25 (Table 1) as well
as their intermediates were synthesized in a commonly used
manner, by fragment condensation, according to schemes pre-
sented in Figures 7–10.
Syntheses
Materials
The applied methods are specified later in the syntheses section.
Physicochemical properties of the inhibitors 7, 11, 18, 25, as well as
newly synthesized intermediates 1, 3, 4, 6, 9, 12, 13, 14, 15, 16, 17,
19, 20, 21, 22, 23, 24, are presented in Tables 2 and 3.
All standard protected Boc amino acid derivatives and
angiotensinogen were obtained from Bachem AG (Switzerland).
Alfa-chymotrypsin, dicyclohexylcarbodiimid, and isopropyl-
magnesium chloride solution were obtained from Sigma-
Aldrich Chemie GmbH (Germany). Acetonitrile isocratic grade
for liquid chromatography and methanol for liquid chromatog-
raphy were acquired at LiChrosolv/Merck Millipore (Germany).
Renin was purchased at Cayman Chemical Company (USA).
Reagents Boc-Phe(4-OMe)-OH, Boc-N-Me-Leu-OH porcine kidney
renin and N-acetylrenin substrate tetradecapeptide were acquired
from recognized vendor. The AHGHA, AHPPA, and AAHOA (1, 12,
19) were synthesized according to the Maibaum protocol. Solvents
were of analytical purity. Tetrahydrofuran (THF) was distilled
from Na/benzophenone under N2. Dichloromethane and
dimethylformamide (DMF) were dried over 4-Å molecular sieves. The
peptides were synthesized by the N,N-dicyclohexylcarbodiimide/1-
hydroxybenzotriazole (DCC/HOBt) method of fragment condensation
in solution. Column Chromatography (CC) on silica gel (Merck, grade
Synthesis of pseudopeptides
It is a two-step method.
In the first step, pseudopeptide Boc-ketoesters are obtained.
Solution (A), containing 10 mmol of Boc-aminoacid (Boc-Arg
Figure 1. Ethyl 4-[N-[N-/N-(t-butoxycarbonyl)-4-methoxyphenylalanyl/-N-
methylleucyl]-amino]-7-(3-nitroguanidino)-3-hydroxyheptanoate Boc-Phe
(4-OMe)-MeLeu-AHGHA-OEt 7.
Figure 3. 6-{N-[4-[N-[N-/N-(t-butoxycarbonyl)-4-methoxyphenylalanyl/-N-
methylleucyl]-amino]-3-hydroxy-5-phenyl-pentanoyl]-amino}-hexanoic acid
isoamylamide Boc-Phe(4-OMe)-MeLeu-AHPPA-Ahx-Iaa18.
J. Pept. Sci. 2016; 22: 106–115
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WINIECKA ET AL.
Figure 4. 6-{N-[4-[N-[N-/N-(t-butoxycarbonyl)-4-methoxyphenylalanyl/-N-
methylleucyl]-amino]-8-benzyloxycarbonylamino-3-hydroxyoctanoyl]-amino}-
hexanoic acid isoamylamide Boc-Phe(4-OMe)-MeLeu-AAHOA-Ahx-Iaa 25.
(NO2)-OH, Boc-Lys(Z)-OH, Boc-Phe-OH) in 30 mL of THF was acti-
vated with 12 mmol of N,N-carbonyldiimidazole. Solution (B),
containing 15mmol of malonic acid monoethyl ester in 30 mL
of THF was activated with 30 mmol of isopropyl magnesium
chloride. Both solutions were mixed together in À20 °C and
agitated. Boc-pseudopeptide esters were obtained in the
second step. Ten mmol of pseudopeptide Boc-ketoester was
dissolved in 100 mL of THF–MeOH mixture (98:2) and then
reduced with 2.5 mmol of NaBH4 in À78 °C [19].
Figure 6. The expected binding sites of the potential new renin inhibitors
with the active center of the renninmolecule.
Identity of diastereoisomers was confirmed in analysis of a
specific rotation, [α]2D0. According to the literature, diastereoisomers
with S,S conformation of the hydroxyethylated pseudodipeptides
exhibit higher specific rotation when compared with the R,S diaste-
reoisomers [20–22], which is as follows: (S,S) AHGHA [α]2D0 = À10.5,
(R,S) AHGHA [α]2D0 = À6.8; (S,S) AAHOA [α]2D0 = À15.6, (R,S)
AAHOA [α]2D0 = À8.43, and (S,S) AHPPA [α]2D0 = À30.0, (R,S) AHPPA
[α]2D0 = À10.5.
Table 1. Biochemical Properties of the Synthesized Compounds, Some
Intermediates and the Reference Compounds
Compound
Compound
NR
IC50 M
Stability [%]* Log P**
Boc-Phe(4-OMe)-
MeLeu-AHGHA-OEt
Boc-Phe(4-OMe)-
MeLeu-AHGHA-
Ahx-Iaa
7
1.7 × 10À6
46.45
3.96
5.44
11
0.96 × 10À8 100 (stable)
Boc-Phe(4-OMe)-
MeLeu-AHPPA-
Ahx-Iaa
18
25
1.05 × 10À9 100 (stable)
7.71
8.17
Boc-Phe(4-OMe)-
MeLeu-AAHOA-
Ahx-Iaa
1.31 × 10À7
42.09
*Fraction of inhibitor amount remaining after 2 h incubation time in
presence of chymotrypsin at 37 °C [18]
**Hydrophobicity of the compounds expressed as log P value was
calculated numerically.
Figure 5. The comparison of the derived renin inhibitor molecules 7, 11,
18, 25 to the angiotensinogen 8-13fragment (positions P3-P3’).
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J. Pept. Sci. 2016; 22: 106–115

NOVEL RENIN INHIBITORS CONTAINING AMINO ACIDS DERIVATIVES
Figure 7. Ethyl 4-[N-[N-/N-(t-butoxycarbonyl)-4-methoxyphenylalanyl/-N-
methylleucyl]-amino]-7-(3-nitroguanidino)-3-hydroxyheptanoate Boc-Phe
(4-OMe)-MeLeu-AHGHA-OEt 7.
Figure 9. 6-{N-[4-[N-[N-/N-(t-butoxycarbonyl)-4-methoxyphenylalanyl/-N-
methylleucyl]-amino]-3-hydroxy-5-phenyl-pentanoyl]-amino}-hexanoic acid
isoamylamide Boc-Phe(4-OMe)-MeLeu-AHPPA-Ahx-Iaa 18.
Introduction of the N-tert-Boc group
Biochemical assay
This group was introduced in a commonly used manner [19].
Determination of inhibition of renin activity
Renin inhibiting activity of the synthesized potential inhibitors was
determined in vitro. HPLC method was used to determine the
concentration of renin substrate. The activity of the compounds
was tested in the range 10À6–10À9 M. Inhibition is expressed as
IC50 value, that is, the molecular concentration of the synthesized
inhibitors causing 50% inhibition of the control renin activity [18].
Removal of the N-tert-Boc group
Boc-amino acid or Boc-peptide (1mmol) in a solution of 4 M HCl in
dioxane (3 n 5 mL) was stirred at room temperature for 30 min. The
solution was conc. in vacuo; then the residue was evaporated twice
with ethyl ether and dried in vacuo [23].
Esterification and hydrolysis
Stability in the presence of α-chymotrypsin
Boc-AHGHA-OEt, Boc-AHPPA-OEt, and Boc-AAHOA-OEt were formed
from mono-ethyl malonate used to prepare these compounds [24]. Al-
kaline hydrolysis of ester group was carried out as described earlier [25].
α-Chymotrypsin was dissolved in phosphatate buffer solution
pH7.8. The solution was incubated at 37°C, and the samples were
collected at the time points 0, 30, 60, 120 min. Then, the samples
were isolated from the solution with diethyl ether, evapo-
rated to dryness, dissolved in mobile phase and determined
by HPLC [18].
Coupling reaction with DCC/HOBt
The amino acid or peptide ester hydrochloride (1 mmol) was
dissolved in CH2Cl2 (5 mL) and neutralized at 0 °C with THF (1 mmol).
Boc-amino acid or Boc-peptide (1 mmol) and HOBt (1.5 mmol) were
added followed by a solution of DCC (1.1 mmol) in CH2Cl2 (5 mL). The
reaction mixture was stirred at 0 °C for 2–4 h and left at RT overnight.
Dicyclohexylurea (DCU) was filtered off and the filtrate was evapo-
rated in vacuo. The residue was dissolved in CHCl3, washed succes-
sively with 5% HCl, 5% NaHCO3, saturated NaCl solution, dried with
anh. MgSO4, and conc. in vacuo. The peptide was purified by silica
gel CC to yield the pure product [26].
Log P value calculation
Because of poor solubility of the compounds in water and in
n-octanol, the Log P values were calculated by a computer
program. Structures of the compounds were modeled with use of
HyperChem 4.5 software, and the semi-empirical MP3 method
was used for single-point calculation. Geometry optimization was
performed by the Polak–Ribier method. Calculation of log P in
HyperChem was carried out using atomic parameters derived by
Ghose et al. [27].
Figure 8. 6-{N-[4-[N-[N-/N-(t-butoxycarbonyl)-4-methoxyphenylalanyl/-N-
methylleucyl]-amino]-7-(3-nitroguanidino)-3-hydroxyheptanoyl]-amino}-
hexanoic acid isoamylamide Boc-Phe(4-OMe)-MeLeu-AHGHAAhx-Iaa 11.
Figure 10. 6-{N-[4-[N-[N-/N-(t-butoxycarbonyl)-4-methoxyphenylalanyl/-N-
methylleucyl]-amino]-8-benzyloxycarbonylamino-3-hydroxyoctanoyl]-amino}-
hexanoic acid isoamylamide Boc-Phe(4-OMe) MeLeu- AAHOA-Ahx-Iaa 25.
J. Pept. Sci. 2016; 22: 106–115
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WINIECKA ET AL.
Table 2. Physicochemical and analytical properties of the synthesized compounds
Compd. No.
Structure
Formula m.w.
Yield (%) M.p. (°C) [α]2D0 (c,MeOH) TLC,Rf (m.ph.)* HPLC (% of purity)
1
Boc-AHGHA-OEt
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
15H27 O7N5 389.41
10H19O3 N5Cl289.34
22H42O8N6 518.62
17H34O6N6Cl468.10
32H53O10N7695.80
32H45 O8N5627.77
41H71O10N9850.05
18H25O5N336.41
31.4 Semisolid À10.5(1.0)
87.0 Semisolid À8.7(1.1)
0.23(A)
0.38(D)
0.64(A)
0.68(D)
0.37(E)
—
3
H-AHGHA-OEt x HCl
—
4
Boc-MeLeu-AHGHA-OEt
47.0 Oil
100.0 Oil
89.0 Oil
+28.0(1.2)
+23.0(1.0)
+50(1.0)
—
6
H-MeLeu-AHGHA-OEt x HCl
Boc-Phe(4-OMe)- MeLeu-AHGHA-OEt
Boc-Phe(4-OMe)- MeLeu-AHGHA-OH
Boc-Phe(4-OMe)- MeLeu-AHGHA-Ahx-Iaa
Boc-AHPPA-OEt
—
7
96.98
—
9
34.0 Semisolid À29.4(1.0)
67.0 Semisolid À28.0(1.0)
0.67(C)
0.46(A)
0.34(F)
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
98.18
—
63.0 80-84
À30.0(1.3)
H-AHPPA-OEt x HCl
13H17 O3NCl 285.89
25H38O6N2462.58
23H41 O6N2 454.65
34H58 O6N4 618.34
29H51 O4N4Cl 554.79
44H69 O8N5 795.00
23H36 O7 N2452.55
18H29 O4N2Cl388.9
30H49 O8N3 579.75
25H42 O6 N3Cl516.09
40H60O10N4756.95
38H56 O10N4728.9
49H78 O10N6911.21
97.0 Semisolid À27(1.0)
43.9 Oil
À61(1.0)
74.0 Semisolid À58(1.0)
37.2 Oil
À100(1.1)
100.0 Semisolid À98(1.0)
14.1 53-57
À94.0(1.0)
0.65(G)
0.62(A)0.43(B)
0.54(B)
0.37(A)
0.46(A)
—
Boc-MeLeu-AHPPA-OEt
—
Boc-MeLeu-AHPPA-OH
—
Boc-MeLeu-AHPPA-Ahx-Iaa
H-MeLeu-AHPPA-Ahx-Iaa x HCl
Boc-Phe(4-OMe)- MeLeu-AHPPA-Ahx-Iaa
Boc-AAHOA-OEt
—
—
0.9(A)0.75(C) 99.78
9.4 Semisolid À15.6(1.01) 0.18(B)
—
—
—
—
—
—
93.5
H-AAHOA x HCl
99.7 Semisolid À8.9(1.0)
60.0 Semisolid À35(1.67)
99.0 Semisolid À29(1.0)
0.47(D)
0.84(A)
0.42(D)
Boc-MeLeu-AAHOA-OEt
H-MeLeu-AAHOA-OEt x HCl
Boc-Phe(4-OMe)- MeLeu-AAHOA-OEt
Boc-Phe(4-OMe)- MeLeu-AAHOA -OH
Boc-Phe(4-OMe)- MeLeu-AAHOA -Ahx-Iaa
35.2 Semisolid À12.6(0.32) 0.86(A)
52.0 Semisolid À16.7(0.16) 0.48(A)
60.8 Semisolid À52.6(0.04) 0.72(A)
*Mobile phase systems (v/v) were: CH3Cl-MeOH 95:5 (A), CH3Cl-MeOH 98:2 (B), Hexane-AcOEt 60:40 (C), BAW (D), CH3Cl-MeOH 90:10 (E), Hexane-AcOEt
80:20 (F), BPW(G)
The elemental analysis results were within 0.4% of theoretical values.
strongly hydrophobic system Ahx–Iaa at the P2’–P3’ position
[25]. The compound 7 was designed in the form of an ester
Results and Discussion
In vitro renin inhibitory activity of all compounds obtained in this
study was within the range 10À6–10À9 M (Table 1). The most active
compound was Boc-Phe(4-OMe)-MeLeu-AHPPA-Ahx-Iaa 18, fea-
turing IC50 = 1.3 × 10À9 M. For comparison, activity of aliskiren
amounts to IC50 = 0.6 × 10À9 M [28]. Structure of the compounds
we obtained was designed on the basis of the fragment of human
angiotensinogen and considerably differs from the aliskiren’s
structure [15,29,30]. Renin inhibition activity, expressed as IC50, of
inhibitors obtained by our team ranged from 10À3 M to 10À7 M.
Structure of the said compounds was developed on the basis of
the structure of the renin substrate’s fragment.
In the compounds 7, 11, and 18, we accounted for possible inter-
action of the substituent at P1 with the hydrophilic sub-pockets
within the S1 area. In particular, we focused our efforts on designing
a hydrophobic moiety P2–P1’. Our aim was to find out whether a
probable intra-molecular relationship between the side chains at
P2 and P1, that are located closely to each other, could reduce or en-
hance hydrophobic interactions of the inhibitor with the enzyme.
The compounds synthesized by us previously [29,31,32], which
contained flexible and branched isobutyl side chains at P2 and P1,
have only moderate inhibitory activity, for example, Boc-
Phe(4-OMe)-MeLeu-Sta-Ahx-EA IC50 = 2.5 × 10À4 M [33]. In this
case, however, moderate activity could result from the pres-
ence of hydrophilic ethanolamine (EA) at the P3’ position of
the C-terminus. On the other hand, the isobutyl substituent
MeLeu and Sta (statin: 4-amino-3-hydroxy-6-methylheptanoic
acid), which are adjacent to each other at P2–P1, do not dis-
turb interaction with the hydrophobic pockets S2 and S1. We
hope to obtain even more active inhibitors in the future. This
paper concerns the compounds 11, 18, and 25 that contain a
in order to compare it with the compound 11 that has an amide
structure. It should allow for verifying results of the studies on
bioactivity and bioavailability as a function of the structure of the
C-terminus of the renin inhibitor molecules [34]. In contrast to the
previously [35] obtained compounds, instead of His, we introduced
a much more hydrophobic MeLeu at P2. Currently, we returned to
an earlier concept, in which histidine was not necessary at the P2
position and may be replaced by synthetic amino acids. Replace-
ment of His at P2 by N-methyl amino acids with a branched alkyl
side chains increases activity of the inhibitors [15,33]. Presumably,
it is caused by hydrophobic interaction of the side chains in these
amino acids with the S2 pocket of the enzyme. In our previous stud-
ies, we had assumed that the enzyme-inhibitor interactions could
be enhanced as a result of introducing hydrophobic aromatic
groups at P2. Poor in vitro inhibitory activity of these inhibitors gives
reason to suppose that the presence of arylhistidine derivatives at
P2 hinders binding between the inhibitor’s molecule and rennin
[30]. No hydrogen bond is formed between the enzyme active site
and the hydrogen atom that is a constituent of the NH group
belonging to the amino acid at the P2 position of the P3–P2 peptide
bond. Therefore, the hydrogen atom could be substituted for a
short alkyl, for example, the methyl group [36–39]. Introduction of
an N-methyl amino acid, such as MeLeu, MeVal, or MeHis, increases
resistance of the P3–P2 bond to proteolytic enzymes, while their af-
finity to renin remains unaffected [40,41]. All compounds obtained
by us contain an unnatural Phe(4-OMe)-MeLeu moiety at the P3–P2
position. Introduction of 4-methoxyphenylalanine at the P3 posi-
tion should secure the peptide bond against proteolytic action of
chymotrypsin in the gastrointestinal tract. An aromatic ring
[15,42] that binds to the hydrophobic pocket S3sp [16,17,43] is
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NOVEL RENIN INHIBITORS CONTAINING AMINO ACIDS DERIVATIVES
J. Pept. Sci. 2016; 22: 106–115
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WINIECKA ET AL.
necessary at the P3 position. The amino group in Phe was
substituted by t-butoxycarbonyl (Boc) group that corresponds to
a branched alkyl at the P4 position. This hydrophobic substituent
presumably interacts with the hydrophobic site S4 of renin. In all
compounds synthesized by us, synthetic pseudodipeptides were
placed at the P1–P1’ position that corresponds with the Leu–Val
bond, which is cleaved by renin (Fig. 5). They are transition-state
analogs of the natural dipeptide Leu–Val. The pseudodipeptide
moiety ensures a good affinity to renin and simultaneously resistance
to its proteolytic activity. The pseudodipeptides used are derivatives
of 4-amino-3-hydroxyacids. With renin, the pseudodipeptides form
hydrogen bonds involving the NH and OH groups. Their side chains
interact with the hydrophobic pocket S1. Except for the hydrophobic
part, the side chain at P1 of the pseudodipeptides AHGHA and
AAHOA contains polar moieties that could form hydrogen bonds
(Fig. 6). We decided to carry out a comparative test of inhibitory ac-
tivity of the compound 18 that contains a purely hydrophobic benzyl
substituent at the P1 position with that of other compounds that
contain pseudodipeptides AHGHA and AAHOA. The compound 18
contains pseudodipeptide AHPPA; its P1 moiety is a phenylalanine
analog. Accordingly, the P1 moiety of the pseudodipeptide AHGHA
7, 11 is an analog of L-arginine. Similarly to Arg, it has a basic guani-
dine structure. S1 sub-pockets, occurring in the large, hydrophobic
pocket, contain fragments, which are hydrogen bond acceptors
[44]. Polar character of the sub-pocket can be explained by the
charge distribution because of the electronic displacement.
Computer-aided molecular charge distribution simulation was car-
ried out with use of ‘Gaussian 03’ computer program for the com-
pound 7 (Fig. 11). The B3LYP/6-31G(d) method with corresponding
databasis was applied for structure geometry optimization and
energy computation of the optimized structure. Results of this
simulation indicate that N2 and N3 nitrogen atoms in nitroguanidine
have alcaline properties. On the basis of these observations, we
hypothesize the polar nitro group not removed from the obtained
inhibitor will facilitate an interaction between the nitroguanidine
residue present at P1 position and the polar sub-pocket at the S1 site.
This additional effect can increase the enzyme-inhibitor interaction.
In order to obtain drugs with potent hypotensive activity, we
considered further renin inhibitors, based on 7 and 11, which
contain a modified L-arginine analog without the protective NO2
group. We expect dual mechanism of action of these drugs—besides
of the inhibitory activity described earlier, the L-arginine is expected
to be a source of endogenous nitrogen monoxide (NO)—a strong
vasodilatory agent [45]. Such a novel class of hybrid drugs, which
in addition to their principal hypotensive activity, release also
nitrogen monoxide, has been developed recently [46–49]. We
assume that because of the presence of guanidine residues,
besides their renin inhibitory activity, the compounds 7 and
11, after removing the protective NO2 group, may also be NO
donors [50]. The compound 25 contains the pseudodipeptide
AAHOA; an expanded moiety of the pseudodipeptide at P1 is
an analog of the lysine side chain. The amino group of the lysine
side chain was substituted by a group comprising a phenyl ring
and an ester linkage, forming urethane (-NH-CO-O-). Such
modification allows for a hydrophobic interaction between the
phenyl ring and a four-carbon aliphatic chain at the S1 pocket.
The polar urethane moiety presumably forms a hydrogen bond
with the renin active site. Because of the possibility of forming
additional bonds in sub-pockets of the enzyme’s hydrophobic
active site by the P1 moieties of the inhibitor’s molecule, the
presence of the polar moiety -NH-CO-O- in the side chain, can
affect not only activity of the inhibitor but also its bioavailability.
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NOVEL RENIN INHIBITORS CONTAINING AMINO ACIDS DERIVATIVES
Figure 11. Molecular charge distribution simulation for the compound 7.
In vitro, the compounds 11 and 18 have been resistant to chymo-
trypsin. The compounds 7 and 25 were unstable in the presence of
chymotrypsin. On the basis of the obtained results of in vitro bioac-
tivity and biostability studies, we can verify assumptions concerning
diversified structure of the side chain at P1 position in the synthe-
sized renin inhibitors. Similarly, we can assess the impact of various
structure of the C-terminus on activity and stability of the inhibitors
7 and 11. The thesis that substitution of His at P2 for MeLeu does not
result in lowering inhibitory activity was confirmed. Moreover, such
substitution may even increase the activity. It proves the significance
of the hydrophobic sub-pocket at the site S2 for establishing a strong
ligand-enzyme bond. The high values of inhibitory activities deter-
mined for the renin inhibitors 11, 18, and 25 allow for ascertaining
lack of adverse intra-molecular interactions between the side chains
at P2 and P1. Therefore, it could be concluded that there could be a
synergistic effect of the hydrophobic substituents P2 and P1 at the
sub-pockets S2-S1’. In two compounds, 18 and 25, the aromatic
benzyl substituent was present at the P1 position in the side chain.
Despite the presence of a polar urethane moiety at this position in
the compound 25, hydrophobicity of the compounds, expressed
as log P 8.17, was the highest. It could be explained by the presence
of an additional hydrophobic aliphatic chain consisting of four car-
bon atoms. A slightly less hydrophobic compound 18 (log P 7.71)
showed the renin inhibitory activity higher by two orders of magni-
tude. Higher activity of the compound 18 at comparable hydropho-
bicity shows significance of the position of an aromatic ring within
the region of the P1 substituent. For the compounds that contain a
phenyl ring, the presence of an additional aliphatic chain 25 is not
required for increasing their activity. A too large substituent or
inadequate location of a polar moiety presumably precludes
fitting hydrophobic moieties and the group -HN-CO-O- to suitable
sub-pockets of the S1 site. A drop of activity of the inhibitor 7 by
two orders of magnitude as compared with activity of the inhibitor
11 results from a various structure of the C-terminal moiety P2’–P3’
for these compounds. The presence of a polar ester group at the
C-terminus of the inhibitor molecule 7 causes a decrease of
hydrophobicity log P to 3.96 and in consequence a lower acti-
vity. This observation suggests that the best approach would be
to incorporate a non-polar, and most preferably a branched moiety,
for example, Ahx–Iaa at the C-terminus, which could enter in hydro-
phobic interactions at the S2’–S3’ site. This is inconsistent with the
observations based on our previous studies, in which an inhibitor
having an ester structure had shown a slightly higher inhibitory
activity as compared with an analogous inhibitor provided with
Ahx–Iaa at the C-terminus. This inconsistency could be
explained by possible difficulty in essential for the activity inter-
action of the P1 moiety with the hydrophobic pocket S1, which
is caused by spatial arrangement of the long, flexible, and
branched Ahx-Iaa chain. The renin inhibitors 7 and 25 were un-
stable in the presence of chymotrypsin. Susceptibility of these
compounds to hydrolytic degradation could presumably result
from the presence of unstable ester bonds at the C-terminus
of the molecule 7 and in the urethane moiety of the substituent
P1 25. Under the same conditions, the inhibitors 11 and 18,
which do not contain an ester bond, have been stable in the
in vitro studies. Activity of proteolytic enzymes toward the
ÀCO–O- and ÀHN–CO–O- bonds that are present in unnatural,
synthetic moieties of the molecule, remains hard to explain. It
seems likely that hydrolysis of these bonds, ÀCO-O- in particu-
lar, could occur under the influence of weakly basic aquatic
environment, in which the analysis was carried out. It remains
an open issue for further investigation. It could be assumed that
probable degradation of the ester linkage in the urethane
moiety of the side chain P1 in the inhibitor molecule 25 under
physiological conditions will have an impact on bioavailability.
Removal of the aromatic benzyloxycarbonyl substituent will
transform the side chain of the pseudodipeptide AAHOH in
the butylamino substituent, as in endogenous lysine. A decrease
of hydrophobicity of the inhibitor and an increase of its polarity
after ionization of the NH2 group in the butyloamino substituent
can decrease bioavailability. However, the presence of the NH2
group creates the possibility of forming an additional hydrogen
bond within the sub-pocket S1. Presumably, formation of a
similar bond at the same site of the inhibitor molecule 18 has
allowed for obtaining a compound with increased renin inhibi-
tory activity as compared with that of the compound 25.
J. Pept. Sci. 2016; 22: 106–115
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WINIECKA ET AL.
of hypertension: design and optimization of
a novel series of
Conclusion
spirocyclic piperidines. Bioorg. Med. Chem. Lett. 2011; 21: 7399.
13 Mori Y, Ogawa Y, Mochizuki A, Nakamura Y, Sugita C, Miyazaki S,
Tamaki K, Matsui Y, Takahashi M, Nagayama T, Nagai Y, Inoue S,
Nishi T. Design and discovery of new (3S,5R)-5-[4-(2-chlorophenyl)-2,2-
dimethyl-5-oxopiperazin-1-yl]piperidine-3-carboxamides as potent
renin inhibitors. Bioorg. Med. Chem. Lett. 2012; 22: 7677.
14 Ostermann N, Ruedisser S, Ehrhardt C, Breitenstein W, Marzinzik A,
Jacoby E, Vangrevelinghe E, Ottl J, Klumpp M, Hartwieg JC, Cumin F,
Hassiepen U, Trappe J, Sedrani R, Geisse S, Gerhartz B, Richert P,
Francotte E, Wagner T, Krömer M, Kosaka T, Webb RL, Rigel DF,
Maibaum J, Baeschlin DK. A novel class of oral direct renin inhibitors:
highly potent 3,5-disubstituted piperidines bearing a tricyclic p3-p1
pharmacophore. J. Med. Chem. 2013; 56: 2196.
Two novel, active and stable renin inhibitors Boc-Phe(4-OMe)-
MeLeu-AHPPA-Ahx-Iaa (18) and Boc-Phe(4-OMe)-MeLeu-AHGHA-
Ahx-Iaa (11), were developed. Furthermore, the second one, after
removing its protective NO2 group, could be considered as a
potential exogenous NO donor. This fact opens up a very interest-
ing prospect for further studies on pharmacotherapy of arterial
hypertension.
Conflict of interest
15 Paruszewski R, Jaworski P, Winiecka I, Tautt J, Dudkiewicz J. New renin
inhibitors with pseudodipeptidic units in P(1)-P(1’) and P(2’)-P(3’)
positions. Chem. Pharm. Bull. 2002; 50: 850.
The authors declare that they have no competing financial interests
16 Chen A, Campeau LC, Cauchon E, Chefson A, Ducharme Y, Dubé D,
Falgueyret JP, Fournier PA, Gagné S, Grimm E, Han Y, Houle R,
Huang JQ, Lacombe P, Laliberté S, Lévesqöue JF, Liu S, Mac Donald D,
Mackay B, McKay D, Percival MD, Regan C, Regan H, St-Jacques R,
Toulmond S. Addressing time-dependent CYP 3A4 inhibition observed
in a novel series of substituted amino propanamide renin inhibitors, a
case study. Bioorg. Med. Chem. Lett. 2010; 20: 5074.
17 Sund C, Belda O, Wiktelius D, Sahlberg C, Vrang L, Sedig S, Hamelink E,
Henderson I, Agback T, Jansson K, Borkakoti N, Derbyshire D,
Eneroth A, Samuelsson B. Design and synthesis of potent macrocyclic
renin inhibitors. Bioorg. Med. Chem. Lett. 2011; 21: 358.
References
1 Mancia G, Fagard R, Narkiewicz K, Redón J, Zanchetti A, Böhm M,
Christiaens T, Cifkova R, De Backer G, Dominiczak A, Galderisi M,
Grobbee DE, Jaarsma T, Kirchhof P, Kjeldsen SE, Laurent S, Manolis AJ,
Nilsson PM, Ruilope LM, Schmieder RE, Sirnes PA, Sleight P,
Viigimaa M, Waeber B, Zannad F. 2013 ESH / ESC Guidelines for the
management of arterial hypertension: The Task Force for the
management of arterial hypertension of the European Society of
Hypertension (ESH) and of the European Society of Cardiology (ESC).
J. Hypertens. 2013; 31: 1281.
18 Marszałek D, Goldnik A, Mazurek AP, Winiecka I. Jaworski P New renin
inhibitors - stability and activity determination. Part I. Acta Pol. Pharm.
2014; 71: 545.
2 James PA, Oparil S, Carter BL, Cushman WC, Dennison-Himmelfarb C,
Handler J, Lackland DT, LeFevre ML, MacKenzie TD, Ogedegbe O,
Smith SC, Jr, Svetkey LP, Taler SJ, Townsend RR, Wright JT, Jr, Narva AS,
Ortiz E. Evidence-based guideline for the management of high blood
pressure in adults: report from the Panel Members Appointed to the
Eighth Joint National Committee (JNC8). JAMA 2014; 311: 507.
3 Weber MA, Schiffrin EL, White WB, Weber MA, Schiffrin EL, White WB,
Mann S, Lindholm LH, Kenerson JG, Flack JM, Carter BL, Materson BJ,
Ram CV, Cohen DL, Cadet JC, Jean-Charles RR, Taler S, Kountz D,
Townsend RR, Chalmers J, Ramirez AJ, Bakris GL, Wang J, Schutte AE,
Bisognano JD, Touyz RM, Sica D, Harrap SB. Clinical practice guidelines
for the management of hypertension in the community: a statement
by the American Society of Hypertension and the International Society
of Hypertension. J. Clin. Hypertens. 2014; 16: 14.
4 Go AS, Bauman MA, Coleman King SM, Fonarow GC, Lawrence W,
Williams KA, Sanchez E. An effective approach to high blood pressure
control. A science advisory from the American Heart Association. J. Am.
Coll. Cardiol. 2014; 63(12): 1230–1238.
5 Tocci G, Paneni F, Palano F, Tocci G, Paneni F, Palano F, Sciarretta S,
Ferrucci A, Kurtz T, Mancia G, Volpe M. Angiotensin – converting
enzyme inhibitors, angiotensin II receptor blockers and diabetes: a
meta – analysis of placebo – controlled clinical trials. Am. J. Hypertens.
2011; 24: 582.
19 Maibaum J, Rich DH. A facile synthesis of statine and analogs by
reduction of β-keto esters from Boc-protected amino acids. HPLC
analyses of their enantiomeric purity. J. Org. Chem.
1988; 53: 869.
20 Steulmann R, Klostermeyer H. Synthesen der (3S4S)-4-Amino-3-hydroxy-
6-methylheptansäure und einiger Derivate. Liebigs Ann. Chem.
1975; 2245: .
21 Iizuka K, Kamijo T, Harada H, Akahane K, Kubota T, Umeyama H, Ishida T,
Kiso Y. Orally Potent Human Renin Inhibitors Derived from
Angiotensinogen Transition State: Design,Synthesis, and Mode of
Interaction. J.Med. Chem 1990; 33: 2707.
22 Schuda PF, Greenlee WJ, Chakravarty PK, Eskola P. A short and efficient
synthesis of (3S,4S)-4-[(tert-butyloxyxarbonyl)amino]-5-cyclohexyl-3-
hydroxypentanoic acid ethyl ester. J. Org. Chem. 1988; 53: 873.
23 Schwyzer R, Sieber P, Kappeler H. On the synthesis of N-t-
butyloxcarbonyl-amino acids. Helv. Chim. Acta 1959; 42: 2622.
24 Anderson GW, McGregor AC. T-butyloxycarbonylamino acids and their
use in peptide synthesis. J. Am. Chem. Soc. 1957; 79: 6180.
25 Paruszewski R, Jaworski P, Tautt J, Dudkiewicz J. New renin inhibitors
containing aliphatic or aromatic or amides at the C-terminus.
Pharmazie 1997; 52: 206.
26 Wolfgang König W, Geiger R. Eine neue Amid-Schutzgruppe. Chem. Ber.
1970; 103: 2041.
27 Ghose AK, Prichett A, Crippen GM. Atomic Physicochemical Parameters
for Three Dimensional Structure Directed Quantitative Structure-
Activity Relationships 111: Modeling Hydrophobic Interactions.
J. Comput. Chem 1988; 9: 80.
28 Wood JM, Maibaum J, Rahuel J, Grütter MG, Cohen NC, Rasetti V,
Rüger H, Göschke R, Stutz S, Fuhrer W, Schilling W, Rigollier P,
Yamaguchi Y, Cumin F, Baum HP, Schnell CR, Herold P, Mah R,
Jensen C, O’Brien E, Stanton A, Bedigian MP. Structure-based design of
aliskiren, a novel orally effective renin inhibitor. Biochem. Biophys. Res.
Commun. 2003; 308: 698.
29 Paruszewski R, Jaworski P, Bodnar M, Dudkiewicz-Wilczyńska J, Roman I.
New renin inhibitors containing pseudodipeptidic units in P3-P2 and P1-
P1’ positions. Chem. Pharm. Bull. 2005; 53: 1305.
6 Wu HY, Huang JW, Lin HJ, Liao WC, Peng YS, Hung KY, Wu KD, Tu YK,
Chien K. Comparative effectiveness of renin-angiotensin system
blockers and other antihypertensive drugs in patients with diabetes:
systematic review and bayesian network meta-analysis.
BMJ 2013; 347: 6008.
7 Jadhav M, Yeola C, Zope G, Nabar A. Aliskiren, the first direct renin
inhibitor for treatment of hypertension: The path of its development.
J. Postgrad. Med. 2012; 58: 32.
8 Bonanni L, Dalla VM. Oral renin inhibitors in clinical practice: a
perspective review. Ther Adv Chronic Dis 2012; 3: 173.
9 Sen S, Sabirli S, Ozyigit T, Uresin Y. Aliskiren review of efficacy and safety
data with focus on past and recent clinical trials. Ther Adv Chronic Dis
2013; 4: 232.
10 Persson F, Rossing P, Parving HH. Direct renin inhibition in chronic
kidney disease. Br. J. Clin. Pharmacol. 2013; 76: 580.
30 Winiecka I, Marszałek D, Goldnik A, Jaworski P, Mazurek AP. Novel renin
inhibitors containing a non-peptide aminoalkanoyl moiety at P1-P1’
position. Pharmazie 2014; 69: 263.
31 Paruszewski R, Tautt J, Dudkiewicz J. Renin inhibitors containing
statine and 6-aminohexanoic acid. Pol. J. Pharmacol. 1993; 45: 75.
32 Paruszewski R, Jaworski P, Tautt J, Dudkiewicz J. Enzymatically stable
renin inhibitors containing statine and 6 aminohexanoic acid. Part IV.
Boll. Chim. Farm. 1994; 133: 301.
11 Bae EH, Kim IJ, Joo SY, Kim EY, Choi JS, Kim CS, Ma SK, Lee J, Kim SW.
Renoprotective effects of the direct renin inhibitor aliskiren on
gentamicin – induced nephrotoxicity in rats. J. Renin Angiotensin
Aldosterone Syst. 2014; 15: 348.
12 Chen A, Aspiotis R, Campeau LC, Cauchon E, Chefson A, Ducharme Y,
Falgueyret JP, Gagné S, Han Y, Houle R, Laliberté S, Larouche G,
Lévesque JF, Mc Kay D, Percival MD. Renin inhibitors for the treatment
wileyonlinelibrary.com/journal/jpepsci
Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.
J. Pept. Sci. 2016; 22: 106–115

NOVEL RENIN INHIBITORS CONTAINING AMINO ACIDS DERIVATIVES
33 Paruszewski R, Jaworski P, Winiecka I, Tautt J, Dudkiewicz J. New renin
inhibitors with hydrophilic C-terminus. Pharmazie 1999; 54: 102.
34 Webb RL, Schiering N, Sedrani R, Maibaum J. Direct renin inhibitors as a
new therapy for hypertension. J. Med. Chem. 2010; 53: 7490.
35 Winiecka I, Marszałek D, Goldnik A, Jaworski P, Mazurek AP. New renin
inhibitors containing phenylalanylhistidyl-γ-amino acid derivatives in
P3 - P1’ position. Acta Pol. Pharm. 2014; 71: 59.
36 Iizuka K, Kamijo T, Harada H, Akahane H, Kubota T, Etoh Y, Shimaoka I,
Tsubaki A, Murakami M, Yamaguchi T, Iyobe A, Umeyama H, Kiso Y.
Synthesis and structure-activity relationships of human renin inhibitors
designed from angiotensinogen transition state. Chem. Pharm. Bull.
1990; 38: 2487.
42 Winiecka I, Dudkiewicz-Wilczyńska J, Roman I, Paruszewski R. New
potential renin inhibitors with dipeptide replacements in the molecule.
Acta Pol. Pharm. 2010; 67: 367.
43 Boger J, Payne LS, Perlow DS, Lohr NS, Poe M, Blaine EH, Ulm EH
Schorn TW, La Mont BT, Lin TV, Kawai M, Rich DH, Veber DF. Renin
Inhibitors.Syntheses of subnanomolar competitive, transition-state
analogue inhibitors containing a novel analogue of Statine. J. Med.
Chem. 1985; 28: 1779.
44 Rahuel J, Rasetti V, Maibaum J, Rüeger H, Göschke R, Cohen NC, Stutz S,
Cumin F, Fuhrer W, Wood JM, Grütter MG. Structure-based drug design:
the discovery of novel nonpeptide orally active inhibitors of human
renin. Chem. Biol. 2000; 7: 493.
37 Kempf DI, de Lara E, Stein HH, Cohen J, Egan DA, Platter II. Renin
inhibitors based on dipeptide analogues. Incorporation of the
hydroxyethylene isosters at the P2/P3 sites. J. Med. Chem. 1990; 33: 371.
38 Doherty AM, Kaltenbronn JS, Hudspeth JP, Repine JT, Roark WH, Sircar I,
Tinney FJ, Conolly CJ, Hodges JC, Taylor MD, Batley BL, Ryan MJ,
Essenburg AD, Rapundalo ST, Weishaar RE, Humblet C, Lunney EA.
New inhibitors of human renin that contain novel replacements at the
P2 site. J. Med. Chem. 1991; 34: 1258.
39 Foundling SI, Cooper J, Watson FE, Cleasby A, Pearl LH, Sibanda BL,
Hemmings A, Woods SP, Blundell TL, Valler MJ, Norey CG, Kay J,
Boger J, Dunn BM, Leckie BJ, Jones DM, Atrash B, Hallett A, Szelke M.
High resolution X-ray analyses of renin inhibitor-aspartic proteinase
complexes. Nature 1987; 327: 349.
45 Channon KM, Guzik T. Mechanisms of superoxide production in human
blood vessels: relationship to endothelial dysfunction, clinical and
genetic risk factors. J. Physiol. Pharmacol. 2002; 53: 515.
46 Breschi MC, Calderone V, Digiacomo M, Martelli A, Martinotti E,
Minutolo F, Rapposelli S, Balsamo A. NO-sartans: a new class of
pharmacodynamic hybrids as cardiovascular drugs. J. Med. Chem.
2004; 47: 5597.
47 Breschi MC, Calderone V, Digiacomo M, Macchia M, Martelli A,
Martinotti E, Minutolo F, Rapposelli S, Rossello A, Testai L, Balsamo A.
New NO-releasing pharmacodynamic hybrids of losartan and its active
metabolite: design, synthesis, and biopharmacological properties.
J. Med. Chem. 2006; 49: 2628.
48 Martelli A, Rapposelli S, Calderone V. NO – releasing hybrids of
40 Thaisrivongs S, Pals DT, Harris DW, Kati WM, Turner SR. Design and
synthesis of a potent and specific renin inhibitor with a prolonged
duration of action in vivo. J. Med. Chem. 1986; 29: 2088.
cardiovascular drugs. Curr. Med. Chem. 2006; 13: 609.
49 Li YQ, Ji H, Zhang YH, Shi WB, Meng ZK, Chen XY, Du GT, Tian J. WB 1106,
a
novel nitric oxide releasing derivative of telmisartan, inhibits
41 Plattner JJ, Marcotte PA, Kleinert HD, Stein HH, Greer J, Bolis G, Fung AK,
Bopp BA, Luly JR, Sham HL. Renin inhibitors. Dipeptide analogues of
hypertension and improves glucose metabolism in rats. Eur. J.
Pharmacol. 2007; 577: 100.
angiotensinogen utilizing
residue to impart proteolytic stability. J. Med. Chem. 1988; 31: 2277.
a
structurally modified phenylalanine
50 Wu G, Morris S. Arginine metabolism: nitric oxide and Beyond. Biochem.
J. 1998; 1: 336.
J. Pept. Sci. 2016; 22: 106–115
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