Advanced Medicinal Chemistry

Filippo Minutolo

CFU 3 (21 hours)

SLIDES E

Selectively-Activated Prodrugs

• pro-diethylstilbestrol (prostate carcinoma)

O

O

PO3=

=O3P

OH

HO

fosfatasi

dietilstilbestrolo difosfato(profarmaco)

dietilstilbestrolo(farmaco attivo)

phosphatase

diethylstilbestrol diphosphate

(prodrug)

diethylstilbestrol

(active drug)

hypoxia

Selectively-Activated Prodrugs

Nature Rev. Cancer 2004, 4, 437-447.

Selectively-Activated Prodrugs

hypoxia

Mol. Med. Today 2000, 6, 157-162.

Selectively-Activated Prodrugs

hypoxia

The Lancet Oncol. 2002, 3, 728-737.

Selectively-Activated Prodrugs

hypoxia

Cervix cellular population distribution based on their oxygen

content (pO2) in various cancer stages

Selectively-Activated Prodrugs

hypoxia

A : healthy tissue

B : stage 0

C : stage 1

D : stage 2

Nature Rev. Cancer 2004, 4, 437-447.

Selectively-Activated Prodrugs

hypoxia

hypoxia-selective antitumor prodrugs

<ox> OFF

<red> ON

hypoxia

“trigger” portion

inactive

active

cytotoxic portion

• nitroaromatics

• quinons

• N-oxides

• sulfoxides

Selectively-Activated Prodrugs

Hypoxia-selective antitumor prodrugs

• nitroaromatic alkylating agents

riduzione

DNA-alchilante

ione aziridinio attivo

Cl-N

Me

Cl

mecloretamina

N

MeCl

Cl

NH(H,OH)

CH2

Cl-

NH(H,OH)

N

Cl

ClMe

Cl-

NO2

N

Me

Cl

Cl

++

+

mostarda inattiva

reduction

inactive mustard

mechlorethamine DNA-alkylating

aziridinium ions

Nature Rev. Cancer 2004, 4, 437-447.

NTR: nitroreductase

DTD: DT-diaphorase

Hypoxia-selective antitumor prodrugs

• nitroaromatic alkylating agents

Nature Rev. Cancer 2004, 4, 437-447.

Hypoxia-selective antitumor prodrugs

• nitroaromatic alkylating agents

• nitroaromatic antimetabolites

N

N

O

O

H F

OO

OH

P

O

N

Me

Cl

O

O2N

O

N

N

O

O

H F

OO

OH

P

O

N

Me

Cl

O

H2N

O

(NHOH)

attivazioneriduttiva

N

N

O

O

H F

OO

OH

P

O-

N

Me

Cl O

....

..

N

N

O

O

H F

OO

OH

P

O-

O

N

Me

+

N

N

O

O

H F

OO

OH

P

O-

O

-O

H2O

N

Me FdUMP(forma attiva)

fosforoammidato dell'FdUMP(profarmaco)

redox

switch

J. Med. Chem. 2001, 44, 4475-4480.

reductive

activation

FdUMP phosphoramidate

(prodrug)

FdUMP

(active form)

Hypoxia-selective antitumor prodrugs

• quinone derivatives (anthracyclines)

MeO

OH

OH

O

O O

OH O

R

O

HO

NH2

Me

doxorubicina (R = OH)daunorubicina (R = H)

riduzione

MeO

OH

OH

OH

OH O

OH O

R

O

HO

NH2

Me

MeO

OH

O

OH

O

OH O

R

DNA

MeO

OH

OH

OH

O

OH O

R

DNA

redox switch

Hypoxia-selective antitumor prodrugs

Doxorubicin (R = OH)

Daunorubicin (R = H)

reduction

• indol-quinones (mitomycin C)

E°(2e-) = – 0.44 V vs. Ag/AgCl

(Med. Chem. Res. 2000, 10:3,

149-163).

Chem. Rev. 2002, 102, 2477-2495.

Hypoxia-selective antitumor prodrugs

• indol-quinone carriers

J. Med. Chem. 2003, 46, 148-154.

Hypoxia-selective antitumor prodrugs

• pyrrole[1,2a]benzimidazol (PBI) aziridines

J. Med. Chem. 1995, 38, 109-118.

Z = OC(O)NH2

T:A base-pair

Hypoxia-selective antitumor prodrugs

• DNA mutations in tumors

Proc. Natl. Acad. Sci. USA 2006, 103, 18238-18242.

random spontaneous mutations

= 1 x 10–8 DNA “base-pairs”

mutazions in tumors (average)

= 210 x 10–8 DNA “base-pairs”

Nature 2007, 446, 153-158.

most frequent mutation:

C:G → T:A

N N

O

N

H

H

N

N

N

N

O

NH

H

H

N

N

N

N

NH H

N N

CH3

O

H

O

T : A

C : G

• DNA mutations in tumors

Nature 2010, 464, 999-1005.

most frequent mutation:

C:G → T:A

• DNA mutations in tumors

Science 2008, 320, 230-233.

N N

O

N

H

H

N

N

N

N

O

NH

H

H

N

N

N

N

NH H

N N

CH3

O

H

O

T : A

C : G

cytidine deaminase enzyme: C->U

Elevated levels in mutations

e. g. HPV -> cancro cervice uterina

DNA methyltransferase (DNMTs):

Covalent addition of Me groups to

cytosine in the dinucleotide C:G pair.

(inactivation of DNA repair system;

possible correlation to exposure to Cr(VI)

in lung cancer)

Mutat. Res. 2009, 670, 42-52.

most frequent mutation:

C:G → T:A

• DNA mutations in tumors

J. Med. Chem. 1995, 38, 109-118.

Z = OC(O)NH2

T:A base-pair

Hypoxia-selective antitumor prodrugs

• pyrrole[1,2a]benzimidazol (PBI) aziridines

• quinone carriers

+

O

O

OH

R

(passaggio veloce)

ciclizzazione intramolecolare

estere metilico del melfalan

MME

H2C N

Cl

Cl

HC

MeOOC

H2N

OH

R

OH

O

NH MME

(passaggio lento)

ambiente riducente

O

O

R

O

NH MME

Pro-MME

R E0 (Volts)

Br

H

-C4H4-

CH3

CH3NH

-0.48

-0.52

-0.63

-0.73

-0.75

Med. Chem. Res. 2000, 10:3, 149-163.

Hypoxia-selective antitumor prodrugs

reductive

environment

(slow step)

intramolecular

cyclization (fast step)

melfalan methyl ester

Bioorg. Med. Chem. Lett. 2007, 17, 1575-1578.

quinone prodrugs for anti-angiogenic oxindoles (semaxanib)

that inhibit vascular endothelial growth factor VEGF

semaxanib

Hypoxia-selective antitumor prodrugs

• quinone carriers

• N-Oxides

Tirapazamine (TPZ)

Cancer Res. 2004, 64, 736-742.

J. Med. Chem. 2003, 46, 169-182.

E°(1) = – 456 mV vs. NHE (Free Radical Res. 1996, 25, 393-399).

Hypoxia-selective antitumor prodrugs

• N-oxides

Tirapazamine (TPZ)

J. Am. Chem. Soc. 2009, 131, 1015-1024.

Hypoxia-selective antitumor prodrugs

• N-oxides

J. Am. Chem. Soc. 2009, 131, 1015-1024.

Hypoxia-selective antitumor prodrugs

• N-oxides

J. Am. Chem. Soc. 2009, 131, 14220-14221.

Hypoxia-selective antitumor prodrugs

• N-oxides

J. Am. Chem. Soc. 2009, 131, 14220-14221.

PBN

Hypoxia-selective antitumor prodrugs

• N-oxides

J. Med. Chem. Soc. 2007, 50, 6392-6404.

J. Med. Chem. Soc. 2007, 50, 6654-6664.

TPZ evolutions

TPZ

• poor tumor penetration

• unsuitable plasma pharmacokinetic

• elevated metabolism (reducton)

• low aqueous solubility at pH 7.4

• scarce lipophilicity

N

NN

O

O

NH2

Hypoxia-selective antitumor prodrugs

J. Med. Chem. Soc. 2007, 50, 6392-6404.

J. Med. Chem. Soc. 2007, 50, 6654-6664.

• 6-MeO: ~ –100mV

• high basicity (Me2N): accelerated activation

• 6-Me: ~ –50mV

• moderate basicity (improved hydrosolubility)

optimal combination of

hydrosolubility and metabolic activation;

improved penetration in the tumor

TPZ

• improved lipophilicity

• membrane permeability

N

NN

O

O

NH2

N

NN

O

O

NH

H3C N

O

N

NN

O

O

NH

CH3ON

CH3

CH3

N

NN

O

O

CH2CH3ON

O

Hypoxia-selective antitumor prodrugs

• N-oxides TPZ evolutions

Nature Rev. Cancer 2004, 4, 437-447.

Hypoxia-selective antitumor prodrugs

• N-oxides

J. Med. Chem. 2006, 49, 713-723.

Hypoxia-selective antitumor prodrugs

• N-oxides

J. Med. Chem. 2006, 49, 713-723.

Hypoxia-selective antitumor prodrugs

• N-oxides

J. Med. Chem. 2006, 49, 713-723.

Hypoxia-selective antitumor prodrugs

• N-oxides

• sulfoxides

riduzione

solfuro solfossido

specie attiva

aziridinio

S NH3C

Cl

SH3C

O

N

Cl

Cl

SH3C N

Cl

Cl

+

(- Cl-)

redox

switch

Hypoxia-selective antitumor prodrugs

reduction

sulfoxide sulfide

aziridinium

(active species)