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Hugo Kubinyi, www.kubinyi.de

Peptidomimeticsand Prodrugs

Hugo Kubinyi

Germany

E-Mail [email protected] www.kubinyi.de


Endogeneous peptidictransmitters

Function

Leu-enkephalin, Met-enkephalin

Ligands of the morphine receptor (analgesics)

Angiotensin II Blood pressure regulationEndothelin Blood pressure regulationNeuropeptide Y Blood pressure regulationSubstance P Different effects, e.g. broncho-

constriction, pain signallingFibrinogen Blood platelet aggregation

Physiological Role of Peptides


NO

Me

NO

Me

O

N

N NMe

NMe

NMe

NMe

O

O

OO

NOO

N

ONMe

OOH

H-Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly-NH2Oxytocin (labor induction)

Cyclosporin A (immunosuppressant)

pGlu-His-Trp-Ser-Tyr-D-Leu-Leu-Arg-Pro-NHEtLeuprolide (LHRH analog, prostate cancer)

H H

H

H

Peptide Drugs


COOH

NH2

COOH

NH2 COOHNH2

COOH

NH2

ααααββββ

PhenylalanineN

O

N

O

ω φ

χ

ψ

CγγγγCββββ

Cαααα

H

H

Phenylalanine and Some Analogs


COOH

NH

N COOH NHNH2

O

NHNH2

ONH

O

NH2

NH2 COOH

F

NH2 COOH

OCH3

NH2 COOH

CH3

CH3

H

NH2 COOHCH3

Other Phenylalanine Analogs


H OH R

R R

N-methyl ketomethylene hydroxyethylene

PX

O O R

O R

phosphonamide, phosphonate, phosphinate; X = -NH-, -O-, -CH2-retro-inverso

N

O

R

N

O

CH3

R

ether reduced amideH

H

N

R

O

R

(E)-ethylene carba

Replacement of the Peptide Bond


NNO

O

RNO

N

OOR

R

N

N

RN

N

O

N

RN

NNN

R

O

S

N

S

NO O

N

N

NO

O

HH

H

H

H H

H

Conformational Stabilization by Cyclisation


Protein Secondary Structure Elements: ß turns


NO

N

SH

O

N

S

O

H

H

O

N

N

N

R

O

R

O

SNH

O

NH O

O

S

NHO

OO

H

H

ONH

NH O

NHO

O

Nφφφφi+1

ψψψψi+1 φφφφi+2

ψψψψi+2

(i)(i+3)

Ri

Ri+2

Ri+3

Ri+1

H

ß-Turn 3D Structure and ß-Turn Mimetics


Structure Ki [nM]

Substance P Arg-Pro-Lys-Pro-Gln-Gln-Phe-Phe-Gly-Leu-Met-NH2

295

Active analog Leu-Gln-Met-Trp-Phe-Gly-NH2 11.7

Ala scan Ala-Gln-Met-Trp-Phe-Gly-NH2 40

Leu-Ala-Met-Trp-Phe-Gly-NH2 138

Leu-Gln-Ala-Trp-Phe-Gly-NH2 156

Leu-Gln-Met-Ala-Phe-Gly-NH2 >10,000

Leu-Gln-Met-Trp-Ala-Gly-NH2 8,300

Leu-Gln-Met-Trp-Phe-Ala-NH2 28

Leu-Gln-Met-Trp-Phe-NH2 200

Dipeptide Z-Trp-Phe-NH2 2,700

Rational Design of NK2 Receptor Antagonists


Rational Design of NK2 Receptor AntagonistsStructure Ki [nM]

Dipeptide Z-Trp-Phe-NH2 2,700

Stabilize the bioactiveconformation

Z-Trp-(R,S)-(αααα-Me)Phe-NH2 327

Optimize theN-terminus

(2,3-di-OCH3)C6H3-CH2OCO-Trp-(R,S)-(αααα-Me)Phe-NH2

37.6

Find activeenantiomer

(2,3-di-OCH3)C6H3CH2OCO-Trp-(R)-(αααα-Me)Phe-NH2

10,000

(2,3-di-OCH3)C6H3CH2OCO-Trp-(S)-(αααα-Me)Phe-NH2

17.2

Attach additionalgroup

(2,3-di-OCH3)C6H3CH2OCO-Trp-(S)-(αααα-Me)Phe-Gly-NH2

1.4


Rational Design of NK2 Receptor Antagonists

N

O N

ON

O

O

NH2R

Ki = 2,700 nM

Ki = 327 nM

Ki = 1.4 nM

N

O N

ON

O

OOO NHR

Ki = 17.2 nM

R = H

R = CH3

R = H

R = CH2CONH2

H

H

H

H

H

H


Optimization of an NK1 Receptor Antagonist

N

N O

O

R

R = H, X = H IC50 >10,000 nM

X

R = Et, X = H IC50 = 3,800 nM

R = H, X = 3,5-di-CH3 IC50 = 1,533 nMR = Ac, X = 3,5-di-CH3 IC50 = 67 nMR = Ac, X = 3,5-di-CF3 IC50 = 1.6 nM

N

NO

CF3

CF3CH3

O

orally available analog

IC50 = 3 nM

H

HH

H


A Small Molecule Insulin Mimetic

O

O

OH

OH

NH

NH

L-783,281

O

O

OH

OH

NH

NH

L-767,827

screening of > 50,000 mixtures of synthetics and natural products yielded the insulin mimetic L-783,281

3-6 µM produce 50% increase of the maximal effect of insulin (in mice)

less active by afactor of 100

B. Zhang et al., Science 284, 974-977 (1999)


N

NHN

O

O

NN O

OH

H

H

N

OCH3

N

HN N

O

Asperlicin(microbial product) ED50 i.v. = 14.8 mg/kg ED50 p.o. > 300 mg/kg

Devazepide, L-364 718

ED50 i.v. = 0.01 mg/kgED50 p.o. = 0.04 mg/kg

H

H

H

N

N

O

HH

N NOH

O

Ki CCK-A (rat) = 1,480 nMKi CCK-B (human) = 0.15 nM

H H

GV 150 013

Ki CCK-A (rat) = 0.37 nMKi CCK-B (human) = 29.5 nM

cf.

CCK-A and CCK-BAntagonists

A. Ursini et al., J. Med. Chem. 43, 3596-3613 (2000)


Design of an Orally Active TRH Mimetic

N

O

O CONH2

N

N

N

NHO

TRH

H

H

metabolically not stable,no oral bioavailability

N

N

CONH2NO

Ph

H

peptidomimetic,orally bioavailable,sufficient half-life time

G. L. Olson et al., J. Med. Chem. 36, 3039-3049 (1993)


Amino Acid Amides as Somatostatin Mimics

NH

NH

N

O NH

NH2R

O

sst2 Ki = 5.9 nM

sst1 Ki = 3,794 nMsst2 Ki = 1.0 nMsst3 Ki = 360 nMsst4 Ki = 2,402 nMsst5 Ki = 2,105 nM

R = H

R = COOMe

NH

NH

N

O NH

NH2t-BuOOC

O

MeN

NHO

sst1 Ki = 2,392 nMsst2 Ki = 0.01 nMsst3 Ki = 31 nMsst4 Ki = 81 nMsst5 Ki = 163 nM

L. Yang et al., Proc. Natl. Acad. Sci. USA 95, 10836-10841 (1998)


A Nonpeptidic Somatostatin Mimic

O

OO

OO

NH2

NH3-deoxy-glucose

mimic of the receptor-recognizing ß-turnPhe7-Trp8-Lys9-Thr10of somatostatin.

IC50 = 1.3 µM (pituitarysomatostatin receptor)

agonist activity in afunctional assay at 3 µM

K. C. Nicolaou et al., Peptide Chem. Struct. Biol., Proceedings of the 11th Am. Peptide Symp., 1990, pp. 881-884; C. Wermuth, The Practice of Medicinal Chemistry, 1996, pp. 571 ff.


A Subtype-Specific Somatostatin Mimic

O

O RO

OO

NH2

NH

O

glucose

R = phenyl non-selective, weak sst-receptor partial agonist

R = imidazol-4-yl 100 nM, selective sst4-receptor agonist

R. Hirschmann et al., J. Med.Chem. 41, 1382-1391 (1998).


NN

O

O COOH

COOH

NH2

NH

N

OCOOEt

NH2

NH

NN

N

OCOOEt

NH2

NH

O

NH2

NH

N NN

NNH2

O

O

O COOH

COOHH H H

H

H

H

HH

H

RGD motif, thebinding domainof integrinreceptor ligands

Stepwise Design of Nonpeptidic, Orally AvailableFibrinogen Receptor Antagonists


Rational Design of Integrin Receptor Ligands

NH

N

ON

N

NH2COOH

O

N

NH

NH2

S SNHN O O

N NO

OCOOH

CH3

H

H

H

H

H

O

NH

NH

ONHO

O

N

COOHNH

O

NNH2

NH

H

H

cyclo(RGDFv)

(v = D-Valine)

R G D

Fv

Ki = 2.0 nM

Ki = 2.3 nM


Superposition of Integrin Receptor Ligands


N

O

N

NO

COOH

NH

NH2H

HN

NCH3

O

O

NN

X COOH

X = NKi GPIIb/IIIa = 8 nMKi ααααvββββ3 = 1,000 nM

X = CHKi GPIIb/IIIa >100,000 nMKi ααααvββββ3 = 9,200 nM

m-amidineKi GPIIb/IIIa = 4,500 nMKi ααααvββββ3 = 510 nM

p-amidineKi GPIIb/IIIa = 26 nMKi ααααvββββ3 = 56,000 nM

H

Selectivity of Integrin Receptor Ligands


HN

N

COOH

CH3

O

O

N

NH

lotrafiban (SB 214 857) Ki GPIIb/IIIa = 2.5 nMKi ααααvββββ3 = 10,340 nM

HN

N

COOH

CH3

O

O

NCH3

N

NH

SB 223 245Ki GPIIb/IIIa = 30,000 nMKi ααααvββββ3 = 2 nM

Highly Selective Integrin Receptor Ligands

Lotrafiban failed in phase III, due to lack of activity and increased mortality (J.-M. Dogné et al., Curr. Med. Chem. 9, 577-589 (2002))


CrystalStructure of the ExtracellularSegment ofIntegrin ααααvß3;complex with cyclo-RGDf-N-MeV

J.-P. Xionget al., Science296, 151-155(2002)


Binding Mode ofcyclo-RGDf-N-MeVto the Extracellular Segment of Integrin ααααvß3


Prodrugs, Soft Drugs and Targeted DrugsProdrugs are inactive (or less active) drug analogs that have better pharmacokinetic properties (e.g.oral bioavailability, BBB penetration) than theirparent drugs. They are (specifically) metabolized to the active form of the drug.Soft drugs are biologically active derivatives of inactive drug analogs , e.g. esters of corticosteroidcarboxylic acids. These esters are (topically) active;after dermal absorption they are readily degraded by metabolic enzymes to inactive analogs.Targeted drugs are drugs or prodrugs that exert their biological action only in certain organs or cells (e.g. Omeprazole, Aciclovir).


Bile, Feces(lipophiliccompounds)

Drug

Metabolites

Metabolites

Gastric/intestinal wall

Portal vein

Organs

Kidneys

Urine (polar compounds)

Cardio-vascularsystem

Liver

Distribution and Metabolism of Drugs in a Biological System


O

CH3COO

CH3COO

N CH3

HH

heroin

Cl

O

CH3 CH3

OR

O

clofibrate, R = Etclofibric acid, R = H

OH H

NH

ORH

O

CHCl2

chloramphenicol (bitter taste), R = H

tasteless prodrug R = CO(CH2)14CH3

O2N

Prodrugs: Esters


Aspirin®, a Prodrug?(Felix Hoffmann, 1897)

OCOCH3

COOH

OH

COOH


OCOOH

CH3

OH

SCoA

OHCOOH

CH3

OHHMG-CoA reductase

HMG-CoAmevalonic acid

O

HOH O

R lovastatin active metabolite

OHCOOH

HOH

R

N NH2

O

F

OH

Cl

blood brainbarrier

NH2 OH

O

progabide

GABA

Prodrugs: Lactones and Amides


Prodrugs: Hydrazides and Azo Compounds

NH2 N N

NH2

SO2NH2

NH2 SO2NH2 NH2 COOH

sulfamidochrysoidine ("prontosil rubrum")

sulfanilamide, an antimetabolite of p-aminobenzoic acid

metabolicdegradation

cf.

N

ROthe metabolite isonicotinic acid(R = -OH) is anantimetabolite ofnicotinic acid

nicotinic acid

N

COOHisoniazide,R = -NH-NH2(tuberculostatic)


N N N

NH NH CH3

CH3

Cl

N N

N

Cl

NH2 NH2

CH3 CH3

bioactivation

proguanil cycloguanil

HHH

Other ProdrugsS

CH3

F

CH3

CH2COOH

O

sulindacS

CH3

F

CH3

CH2COOH

bioactivation


OHN

CH3

RO

RO

Dipivefrine, R = COC(CH3)3

Epinephrine, R = H

SNN

N

O

O NX

CH3

CH3

CH3

Oxime ether, X = N-OCH3

Ketone, X = O

Timolol, X = H, OH

HH

Dipivefrine is 20x faster metabolized in the eye than in the periphery. The timolol prodrug is only metabolized in the eye. Both prodrugs are used for the therapy of glaucoma.

Drug Targeting into the Eye


Kidney-Selective Release of Sulfamethoxazole

NH

O

NH

O

Me

SNH

NO

Me

OO

COOH

1) N-acylamino acid deacylase

2) γγγγ-glutamyl transpeptidase NH2

SNH

NO

Me

OO

both enzymes are present inhigh concentration in the kidney

C. G. WermuthThe Practiceof MedicinalChemistry, Academic Press,New York 1996, pp. 684-685


NCH3

NCH3+

NCH3+

+

enzymaticoxidation

NCH3

R

MPTP toxic metabolitesPethidine, R = COOEtMPPP, R = OCOEt

1-methyl-4-phenyl-4-propionyloxy-piperidine (MPPP) corresponds to pethidine but a “leaving group” results. Consumption of impure material leads to severe Parkinson symptoms, followed by early death. MPTP is a “prodrug” of permanently charged cytototoxic metabolites. The MAO inhibitor selegilin prevents this oxidation.

Drug Abuse Leads to a New Prodrug Concept


N

X drug

O

CH3

H Hperiphery blood brain barrier brain

N

X drug

O

CH3

H H

N

X drug

O

CH3

+ N

X drug

O

CH3

fastelimination

metabolic cleavage

freedrug

metabolic activation

+

neutral,lipophilic

charged,polar form

Brain Targeting of Drugs

However,

!!!! ?


Omeprazole Case Study

O NH

OO

NNH2

S

NS

NH

N NSO

NH

N

1966: Local anesthetics reduce gastric secretion (Hässle)1966-1972: First lead1972-1979: New lead pyridyl- acetamide (from screening of antiviral compounds) Active analogs; metabolite with higher antisecretory activity


Picoprazole, 1976preclinical candidate

Omeprazole Case Study

Tox study:

vasculitis

picoprazole group placebo group

breeding dogFabian

OS

NH

NMeOOC

MeN

Me


N

NS

N

O

CH3OMe

CH3

MeO

N

N

S

N

OH

CH3OMe

CH3MeO

+H+

N

NN

S

CH3

OMe

CH3

MeO

+ATPase-SH

N

NN

CH3

OMe

CH3S

S

MeO

+

ATPase

omeprazole

H

H

H

Drug Activation in Acid-Producing Cells - A Serendipitous Discovery of a Targeted Drug


Omeprazole Activation in Acid-Producing Cells

Distribution ofradio-labelledomeprazole,one minute afteri.v. injection, rat

sixteen hours after i.v. injection, rat

courtesy of Dr. K. Andersson, AstraZeneca, Sweden

liverstomachkidney


Omeprazole Activation in Acid-Producing Cells

Distribution ofradio-labelledomeprazole,one minute afteri.v. injection, rat

sixteen hours after i.v. injection, rat

courtesy of Dr. K. Andersson, AstraZeneca, Sweden

liverstomachkidney


NN

O COOH

CH3

ROOC

enalapril, R = Et

enalaprilate, R = HN

R2

N

O

O

R1

EtOOC

diketopiperazine

R1 = phenethyl, R2 = MeH

NH2OH

OH

NH2OH

OH COOHdopamine L-dopa

Use of the AA and Dipeptide Transporters


O

NHP N

Cl

Cl

O

O

NHP N

Cl

Cl

O

OH

Cyclophosphamide

NHCl

Cl NH-Lost acrolein

O

Mustard gas

N-Lost, R = CH3SCl

ClN

Cl

ClR

N-Aryl-Lost, R = Aryl

metabolic activation in the liver

+

Pro-Prodrugs


CH3 NH2

N

OOH

OH

COOHH

αααα-Methyldopa-Phe

CH3

NH2OH

OH

OH

αααα-Methylnorepinephrine

The dipeptide αααα-Methyldopa-Phe is readily absorbed as a substrate of the dipeptide transporter. In the first pass, αααα-Methyldopa is produced, a substrate of the amino acid transporter. Transport into the brain, decar-boxylation and hydroxylation produces a „false neuro-transmitter“, the α α α α2 agonist αααα-Methylnorepinephrine.

A Most Elegant Prodrug Concept


NH

N N

N

NH2

O

OOH

NH

N N

N

NH2

O

OO

ONH2

MeMe

valaciclovir,a pro-prodrug

NH

N N

N

NH2

O

OO-P

aciclovir

1) monophosphorylation by viral thymidine kinase

2) phosphorylation by cellular kinase

NH

N N

N

NH2

O

OO-P-P-P

DNA polymerase inhibition (chain termination)

Antiviral Prodrugs are Trojan Horses


famciclovir

N

N N

N

NH2 OAc

OAc penciclovir

NH

N N

N

NH2 OH

OH

O

triphosphate(active form; DNA chain termination)

zidovudine(azidothymidine, AZT)

NH

N

O

O

Me

OOH

N3

intracellularphosphorylation

triphosphate(inhibits reverse transcriptase; inactive against incorporated viruses)

Antiviral Prodrugs are Trojan Horses


NH

N

O

O

F

5-fluorouracilH

NH

N

O

O

F

O

OH

OH

NH

N

O

O

F

O

OH

O-P-P-P

5-F-uridylate

NH

N

NH

O

F

O

OH

Me

OH

O

OMe

capecitabine orally active prodrug, tumour-specific activation by a cascade of enzymes:1) carboxypeptidase cleavage (liver)2) cytidine deaminase (liver, tumours)3) thymidine phosphorylase (tumours)

(a thymidylate synthase inhibitor)

Prodrugs of Site-Specific Trojan Horses

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