Bioreductive activation of a series of indolequinones by human DT-diaphorase

structure-activity relationships

R M Phillips, M A Naylor, M Jaffar, S W Doughty, S A Everett, A G Breen, G A Choudry, I J Stratford

Research output: Contribution to journalArticle

66 Citations (Scopus)

Abstract

A series of indolequinones including derivatives of EO9 bearing various functional groups and related indole-2-carboxamides have been studied with a view to identifying molecular features which confer substrate specificity for purified human NAD(P)H:quinone oxidoreductase (DT-diaphorase), bioreductive activation to DNA-damaging species, and selectivity for DT-diaphorase-rich cells in vitro. A broad spectrum of substrate specificity exists, but minor changes to the indolequinone nucleus have a significant effect upon substrate specificity. Modifications at the 2-position are favorable in terms of substrate specificity as these positions are located at the binding site entrance as determined by molecular modeling studies. In contrast, substitutions at the (indol-3-yl)methyl position with bulky leaving groups or a group containing a chlorine atom result in compounds which are poor substrates, some of which inactivate DT-diaphorase. Modeling studies demonstrate that these groups sit close to the mechanistically important amino acids Tyr 156 and His 162 possibly resulting in either alkylation within the active site or disruption of charge-relay mechanisms. An aziridinyl group at the 5-position is essential for potency and selectivity to DT-diaphorase-rich cells under aerobic conditions. The most efficient substrates induced qualitatively greater single-strand DNA breaks in cell-free assays via a redox mechanism involving the production of hydrogen peroxide (catalase inhibitable). This damage is unlikely to form a major part of their mechanism of action in cells since potency does not correlate with extent of DNA damage. In terms of hypoxia selectivity, modifications at the 3-position generate compounds which are poor substrates for DT-diaphorase but have high hypoxic cytotoxicity ratios.

Original languageEnglish
Pages (from-to)4071-80
Number of pages10
JournalJournal of Medicinal Chemistry
Volume42
Issue number20
DOIs
Publication statusPublished - 7 Oct 1999
Externally publishedYes

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Indolequinones
NAD(P)H Dehydrogenase (Quinone)
Structure-Activity Relationship
Substrate Specificity
apaziquone
Single-Stranded DNA Breaks
Chlorine
Alkylation
NAD
Catalase
Hydrogen Peroxide
DNA Damage
Oxidation-Reduction
Catalytic Domain
Oxidoreductases
Binding Sites
Amino Acids
DNA

Cite this

Phillips, R M ; Naylor, M A ; Jaffar, M ; Doughty, S W ; Everett, S A ; Breen, A G ; Choudry, G A ; Stratford, I J. / Bioreductive activation of a series of indolequinones by human DT-diaphorase : structure-activity relationships. In: Journal of Medicinal Chemistry. 1999 ; Vol. 42, No. 20. pp. 4071-80.
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title = "Bioreductive activation of a series of indolequinones by human DT-diaphorase: structure-activity relationships",
abstract = "A series of indolequinones including derivatives of EO9 bearing various functional groups and related indole-2-carboxamides have been studied with a view to identifying molecular features which confer substrate specificity for purified human NAD(P)H:quinone oxidoreductase (DT-diaphorase), bioreductive activation to DNA-damaging species, and selectivity for DT-diaphorase-rich cells in vitro. A broad spectrum of substrate specificity exists, but minor changes to the indolequinone nucleus have a significant effect upon substrate specificity. Modifications at the 2-position are favorable in terms of substrate specificity as these positions are located at the binding site entrance as determined by molecular modeling studies. In contrast, substitutions at the (indol-3-yl)methyl position with bulky leaving groups or a group containing a chlorine atom result in compounds which are poor substrates, some of which inactivate DT-diaphorase. Modeling studies demonstrate that these groups sit close to the mechanistically important amino acids Tyr 156 and His 162 possibly resulting in either alkylation within the active site or disruption of charge-relay mechanisms. An aziridinyl group at the 5-position is essential for potency and selectivity to DT-diaphorase-rich cells under aerobic conditions. The most efficient substrates induced qualitatively greater single-strand DNA breaks in cell-free assays via a redox mechanism involving the production of hydrogen peroxide (catalase inhibitable). This damage is unlikely to form a major part of their mechanism of action in cells since potency does not correlate with extent of DNA damage. In terms of hypoxia selectivity, modifications at the 3-position generate compounds which are poor substrates for DT-diaphorase but have high hypoxic cytotoxicity ratios.",
keywords = "Amino Acid Sequence, Antineoplastic Agents/chemical synthesis, Aziridines/chemical synthesis, Cell Hypoxia, DNA Damage, Humans, Indolequinones, Indoles/chemical synthesis, Models, Molecular, Molecular Sequence Data, NAD(P)H Dehydrogenase (Quinone)/antagonists & inhibitors, Oxidation-Reduction, Structure-Activity Relationship, Substrate Specificity, Tumor Cells, Cultured",
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Phillips, RM, Naylor, MA, Jaffar, M, Doughty, SW, Everett, SA, Breen, AG, Choudry, GA & Stratford, IJ 1999, 'Bioreductive activation of a series of indolequinones by human DT-diaphorase: structure-activity relationships', Journal of Medicinal Chemistry, vol. 42, no. 20, pp. 4071-80. https://doi.org/10.1021/jm991063z

Bioreductive activation of a series of indolequinones by human DT-diaphorase : structure-activity relationships. / Phillips, R M; Naylor, M A; Jaffar, M; Doughty, S W; Everett, S A; Breen, A G; Choudry, G A; Stratford, I J.

In: Journal of Medicinal Chemistry, Vol. 42, No. 20, 07.10.1999, p. 4071-80.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Bioreductive activation of a series of indolequinones by human DT-diaphorase

T2 - structure-activity relationships

AU - Phillips, R M

AU - Naylor, M A

AU - Jaffar, M

AU - Doughty, S W

AU - Everett, S A

AU - Breen, A G

AU - Choudry, G A

AU - Stratford, I J

PY - 1999/10/7

Y1 - 1999/10/7

N2 - A series of indolequinones including derivatives of EO9 bearing various functional groups and related indole-2-carboxamides have been studied with a view to identifying molecular features which confer substrate specificity for purified human NAD(P)H:quinone oxidoreductase (DT-diaphorase), bioreductive activation to DNA-damaging species, and selectivity for DT-diaphorase-rich cells in vitro. A broad spectrum of substrate specificity exists, but minor changes to the indolequinone nucleus have a significant effect upon substrate specificity. Modifications at the 2-position are favorable in terms of substrate specificity as these positions are located at the binding site entrance as determined by molecular modeling studies. In contrast, substitutions at the (indol-3-yl)methyl position with bulky leaving groups or a group containing a chlorine atom result in compounds which are poor substrates, some of which inactivate DT-diaphorase. Modeling studies demonstrate that these groups sit close to the mechanistically important amino acids Tyr 156 and His 162 possibly resulting in either alkylation within the active site or disruption of charge-relay mechanisms. An aziridinyl group at the 5-position is essential for potency and selectivity to DT-diaphorase-rich cells under aerobic conditions. The most efficient substrates induced qualitatively greater single-strand DNA breaks in cell-free assays via a redox mechanism involving the production of hydrogen peroxide (catalase inhibitable). This damage is unlikely to form a major part of their mechanism of action in cells since potency does not correlate with extent of DNA damage. In terms of hypoxia selectivity, modifications at the 3-position generate compounds which are poor substrates for DT-diaphorase but have high hypoxic cytotoxicity ratios.

AB - A series of indolequinones including derivatives of EO9 bearing various functional groups and related indole-2-carboxamides have been studied with a view to identifying molecular features which confer substrate specificity for purified human NAD(P)H:quinone oxidoreductase (DT-diaphorase), bioreductive activation to DNA-damaging species, and selectivity for DT-diaphorase-rich cells in vitro. A broad spectrum of substrate specificity exists, but minor changes to the indolequinone nucleus have a significant effect upon substrate specificity. Modifications at the 2-position are favorable in terms of substrate specificity as these positions are located at the binding site entrance as determined by molecular modeling studies. In contrast, substitutions at the (indol-3-yl)methyl position with bulky leaving groups or a group containing a chlorine atom result in compounds which are poor substrates, some of which inactivate DT-diaphorase. Modeling studies demonstrate that these groups sit close to the mechanistically important amino acids Tyr 156 and His 162 possibly resulting in either alkylation within the active site or disruption of charge-relay mechanisms. An aziridinyl group at the 5-position is essential for potency and selectivity to DT-diaphorase-rich cells under aerobic conditions. The most efficient substrates induced qualitatively greater single-strand DNA breaks in cell-free assays via a redox mechanism involving the production of hydrogen peroxide (catalase inhibitable). This damage is unlikely to form a major part of their mechanism of action in cells since potency does not correlate with extent of DNA damage. In terms of hypoxia selectivity, modifications at the 3-position generate compounds which are poor substrates for DT-diaphorase but have high hypoxic cytotoxicity ratios.

KW - Amino Acid Sequence

KW - Antineoplastic Agents/chemical synthesis

KW - Aziridines/chemical synthesis

KW - Cell Hypoxia

KW - DNA Damage

KW - Humans

KW - Indolequinones

KW - Indoles/chemical synthesis

KW - Models, Molecular

KW - Molecular Sequence Data

KW - NAD(P)H Dehydrogenase (Quinone)/antagonists & inhibitors

KW - Oxidation-Reduction

KW - Structure-Activity Relationship

KW - Substrate Specificity

KW - Tumor Cells, Cultured

U2 - 10.1021/jm991063z

DO - 10.1021/jm991063z

M3 - Article

VL - 42

SP - 4071

EP - 4080

JO - Journal of Medicinal Chemistry

JF - Journal of Medicinal Chemistry

SN - 0022-2623

IS - 20

ER -