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Cited by 293Antioxidant Activity and Oxidative StressRedox biology and oxidative stressMetal-Catalyzed Oxygenation Mechanisms

Antioxidant Protective Mechanisms against Reactive Oxygen Species (ROS) Generated by Mitochondrial P450 Systems in Steroidogenic Cells

Hanukoglu, Israel·2006·Drug Metabolism Reviews
DOI 10.1080/03602530600570040
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Abstract

Mitochondrial P450 type enzymes catalyze central steps in steroid biosynthesis, including cholesterol conversion to pregnenolone, 11beta and 18 hydroxylation in glucocorticoid and mineralocorticoid synthesis, C-27 hydroxylation of bile acids, and 1alpha and 24 hydroxylation of 25-OH-vitamin D. These monooxygenase reactions depend on electron transfer from NADPH via FAD adrenodoxin reductase and 2Fe-2S adrenodoxin. These systems can function as a futile NADPH oxidase, oxidizing NADPH in absence of substrate, and leak electrons via adrenodoxin and P450 to O(2), producing superoxide and other reactive oxygen species (ROS). The degree of uncoupling depends on the P450 and steroid substrate. Studies with purified proteins and overexpression in cultured cells show consistently that adrenodoxin, but not reductase, is responsible for ROS production that can lead to apoptosis. In the ovary and corpus luteum, antioxidant enzyme activities superoxide dismutase, catalase, and glutathione peroxidase parallel steroidogenesis. Antioxidant beta-carotene, alpha-tocopherol, and ascorbate can protect against oxidative damages of P450 systems. In testis Leydig cells, steroidogenesis is associated with aging of the steroidogenic capacity.

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Written from the paper’s full text.

TL;DR

This review synthesizes evidence that mitochondrial P450 systems in steroidogenic cells can leak electrons to O₂, generating ROS, with adrenodoxin as a key mediator and P450c11 more uncoupled than P450scc. It describes antioxidant defenses—SOD, catalase, glutathione peroxidase, ascorbate, tocopherol, and β-carotene—that parallel steroidogenesis and can protect against oxidative damage.

Key findings

  • Reconstituted bovine mitochondrial P450 components act as a futile NADPH oxidase: AdR alone had O₂ reduction <0.001 mol e⁻/min/mol AdR, but AdR + adrenodoxin increased to 149 ± 34, and AdR + adrenodoxin + P450scc increased further to 721 ± 125 mol e⁻/min/mol AdR.
  • P450c11 is much more leaky than P450scc: in reconstituted systems, at most 15% of total electron flow in the P450scc system went to ROS formation, whereas 32–43% of electrons were consumed in ROS generation by P450c11.
  • Adrenodoxin, not adrenodoxin reductase, appears responsible for ROS production leading to apoptosis: overexpression of human or bovine adrenodoxin decreased cell viability in all 11 cell lines tested, while an apo-mutant adrenodoxin (C46S) lacking the 2Fe-2S cluster did not cause apoptosis; AdR overexpression alone did not increase ROS or apoptosis.
  • Antioxidant enzyme activities parallel steroidogenesis: in bovine corpora lutea, SOD and catalase activities peak at about day 16 of the estrous cycle and then drop in parallel with P450scc and adrenodoxin levels; ascorbate concentrations are highest in steroidogenic tissues such as adrenal cortex and corpus luteum.

Methods

  • Narrative review of published studies on mitochondrial P450 systems, ROS generation, and antioxidant protection in steroidogenic cells.
  • Evidence reviewed includes reconstituted systems with purified bovine mitochondrial P450 proteins, cultured-cell overexpression experiments, and animal tissue studies of adrenal cortex, ovary/corpus luteum, and testis Leydig cells.
  • Main analysis is qualitative synthesis, supported by tables of electron-transfer rates, redox potentials, steroid effects on P450c11 leakage, and antioxidant levels in steroidogenic tissues.

Limitations

  • The paper states that its summary points apply to the specific cases reviewed and “do not represent general rules for all mitochondrial P450 and antioxidant combinations in different systems.”
  • The paper notes that there is currently no precise information on absolute concentrations of NADH and NADPH in the mitochondrial matrix where steroidogenic enzymes are located.
  • Evident from the text: this is a narrative review without a systematic search or meta-analysis, and it compares findings across different species, tissues, temperatures, and cell models; the paper also acknowledges that adrenodoxin overexpression conclusions may be questioned because those studies used non-steroidogenic cells.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1080/03602530600570040

Cites

150 of 150 references verified0 citation errors · 0 not checkable

Statistics

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Claims the paper makes

0 of 187 cited sources checked · 0 supported · 0 flagged

  • Interpretationcitation
    § Israel Hanukoglu

    Studies with purified proteins and overexpression in cultured cells show consistently that adrenodoxin, but not adrenodoxin reductase, is responsible for ROS production.

    “Studies with purified proteins and overexpression in cultured cells show consistently that adrenodoxin, but not reductase, is responsible for ROS production”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Hanukoglu et al., 1993

      Not checked in the free run.

    • cites Rapoport et al., 1995

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  • Premisecitation
    § Studies with Purified Enzymes

    Addition of adrenodoxin greatly stimulates the rate of NADPH oxidation and O2 reduction.

    “Addition of adrenodoxin greatly stimulates the rate of NADPH oxidation and O 2 reduction.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Hanukoglu et al., 1993

      Not checked in the free run.

  • Interpretationreasoning
    § Electron Transfer in Mitochondrial P450 Systems

    Even if mitochondrial P450 systems leak electrons at a low rate, their total capacity for free radical generation could be high, especially in steroidogenic tissues.

    “Thus, even if these P450 systems leak electrons at a low rate, their total capacity for free radical generation could be high, especially in steroidogenic tissues.”
    Quote in the paperSubstantial claim
  • Premisecitation
    § Studies with Purified Enzymes

    The P450scc system produced less H2O2 during cholesterol substrate hydroxylation than that observed in the absence of substrate.

    “P450scc system produced less H 2 O2 during cholesterol substrate hydroxylation than that observed in the absence of substrate.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Rapoport et al., 1995

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  • Premisecitation
    § Studies with Purified Enzymes

    In adrenal mitochondria, the concentrations of P450scc and adrenodoxin are similar.

    “In adrenal mitochondria the concentrations of P450scc and adrenodoxin are similar”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Hanukoglu and Hanukoglu, 1986

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  • May combine two claims. 33
  • Classified as probably not a substantial claim. 26

  • May combine two claims.

    Premisecitation
    § Studies with Purified Enzymes

    Adrenodoxin reductase reduced by NADPH remains reduced and does not readily oxidize by itself in aerobic solution.

    “In aerobic solution, adrenodoxin reductase that is reduced by NADPH remains reduced and does not readily oxidize by itself”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites Chu and Kimura, 1973

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    • cites Hanukoglu et al., 1993

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    • cites Sugiyama et al., 1979

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    Premisecitation
    § Studies with Purified Enzymes

    11β-hydroxylated products of P450c11, and other steroids with strict stereo-specificity, strongly stimulated electron leakage from P450c11, but not from P450scc.

    “In contrast, 11 β -hydroxylated products of P450c11, and other steroids with a strict stereo-specificity, strongly stimulated electron leakage from P450c11, but not from P450scc”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Rapoport et al., 1995

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  • May combine two claims.

    Premisecitation
    § Israel Hanukoglu

    Mitochondrial P450 type enzymes catalyze central steps in steroid biosynthesis, including cholesterol conversion to pregnenolone, 11β and 18 hydroxylation in glucocorticoid and mineralocorticoid synthesis, C-27 hydroxylation of bile acids, and 1α and 24 hydroxylation of 25-OH-vitamin D.

    “Mitochondrial P450 type enzymes catalyze central steps in steroid biosynthesis, including cholesterol conversion to pregnenolone, 11 β and 18 hydroxylation in glucocorticoid and mineralocorticoid synthesis, C-27 hydroxylation of bile acids, and 1 α and 24 hydroxylation of 25-OH-vitamin D.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Hanukoglu, 1992

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    • cites Miller, 2005

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  • May combine two claims.

    Premisecitation
    § Studies with Purified Enzymes

    Both P450scc and P450c11 generate ROS during their catalytic function of steroid hydroxylation.

    “A study that examined ROS formation in reconstituted mitochondrial P450 systems revealed that both P450scc and P450c11 generate ROS during their catalytic function of steroid hydroxylation”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Rapoport et al., 1995

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  • May combine two claims.

    Premisecitation
    § Mitochondrial P450 Systems as a Source of ROS in Cultured Cells

    Adrenodoxin expression enhanced oxidation of dihydroethidium to ethidium, providing evidence for generation of ROS in the cell lines.

    “Adrenodoxin expression enhanced oxidation of dihydroethidium to ethidium, providing evidence for the generation of ROS in the cell lines.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Derouet-Humbert et al., 2005

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  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Premisenone given
    § Mitochondrial P450 Systems as a Source of ROS in Cultured Cells

    In steroidogenic cells there are no major vesicular stores of steroid products, as steroids are rapidly secreted into the blood stream after synthesis.

    “In steroidogenic cells there are no major vesicular stores of steroid products, as steroids are rapidly secreted into the blood stream after synthesis.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation
    § Mitochondrial P450 Systems as a Source of ROS in Cultured Cells

    Cytochrome c aggregates with Apaf-1 and procaspase-9 forming apoptosomes; caspase-9 is cleaved and activated by apoptosomes and then activates downstream effector caspases (caspase-3 and -7), spreading a proteolytic cascade.

    “Cytochrome c aggregates with apoptosis-protease-activating factor 1 (Apaf-1), and procaspase-9 forming apoptosomes. Caspase-9 is cleaved and activated by the apoptosomes and then it activates downstream effector caspases (caspase-3 and -7), spreading a cascade of proteolytic activity that leads to digestion of structural proteins in the cytoplasm and eventual phagocytosis of the cell (Bras et al.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Bras et al., 2005

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    Premisecitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    The first step of steroid hormone biosynthesis in all steroidogenic tissues is cleavage of the side-chain of cholesterol by P450scc, producing pregnenolone.

    “The first step of steroid hormone biosynthesis in all steroidogenic tissues is the cleavage of the side-chain of cholesterol by P450scc that produces pregnenolone (Hanukoglu, 1992; Miller, 2005; Payne and Hales, 2004).”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites Hanukoglu, 1992

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    • cites Miller, 2005

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    • cites Payne and Hales, 2004

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    Premisecitation
    § Mitochondrial P450 Systems as a Source of ROS in Cultured Cells

    The addition of 1α,25-dihydroxyvitamin D3 induces apoptosis in human breast cancer MCF-7 cells by disruption of mitochondrial function, associated with cytochrome c release, and production of reactive oxygen species.

    “The addition of this steroid derivative induces apoptosis in human breast cancer MCF-7 cells by disruption of mitochondrial function, associated with cytochrome c release, and production of reactive oxygen species (Narvaez and Welsh, 2001; Narvaez et al., 2003).”
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    • cites Narvaez and Welsh, 2001

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    • cites Narvaez et al., 2003

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    Interpretationreasoning
    § Mitochondrial P450 Systems as a Source of ROS in Cultured Cells

    Steroidal drugs may have similar effects stimulating ROS production by steroid metabolizing enzymes.

    “However, experimental observations noted previously raise a caveat that steroidal drugs may have similar effects stimulating ROS production by steroid metabolizing enzymes.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation
    § Mitochondrial P450 Systems as a Source of ROS in Cultured Cells

    AdR over-expression by itself is not associated with increased ROS formation or ROS-triggered apoptosis.

    “Consistent with these findings, AdR over-expression by itself is not associated with increased ROS formation or ROS triggered apoptosis (Derouet-Humbert et al., 2005).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Derouet-Humbert et al., 2005

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  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Studies with Purified Enzymes

    In other P450 systems, various substrates and substrate analogs show wide variation in their effects on the coupling of the electron transfer process.

    “In other P450 systems, various substrates and substrate analogs show wide variation in their effects on the coupling of the electron transfer process”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Jung et al., 2002

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    • cites Shertzer et al., 2004a, 2004b

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    Premisecitation
    § Mitochondrial P450 Systems as a Source of ROS in Cultured Cells

    Overexpression of adrenodoxin disrupts mitochondrial transmembrane potential, indicating breakdown of the outer mitochondrial membrane and increased caspase activity.

    “Consistent with the process of apoptosis, overexpression of adrenodoxin was shown to disrupt mitochondrial transmembrane potential, indicating breakdown of the outer mitochondrial membrane and increased caspase activity in the cell (Derouet-Humbert et al., 2005).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Derouet-Humbert et al., 2005

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  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Interpretationreasoning
    § Studies with Purified Enzymes

    Steroids that have no effect on electron leakage may not enter the substrate pocket of P450, or may simply not affect the heme-O2 interaction in the active site.

    “The steroids that have no effect on electron leakage may not enter into the substrate pocket of P450, or simply not affect the heme-O 2 interaction in the active site.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Premisecitation
    § Mitochondrial P450 Systems as a Source of ROS in Cultured Cells

    Difference in the availability of mitochondrial cholesterol might contribute to the observed tissue specificity of CYP11A1-induced apoptosis.

    “leading the authors to conclude that 'difference in the availability of mitochondrial cholesterol might contribute to the observed tissue specificity of CYP11A1induced apoptosis' (Derouet-Humbert et al., 2005).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Derouet-Humbert et al., 2005

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  • May combine two claims.

    Premisereasoning
    § Mitochondrial P450 Systems as a Source of ROS in Cultured Cells

    The loss of P450c11 activity is not accompanied by loss of steroid synthesis, indicating that P450scc continues to function with little or no damage under the same conditions.

    “The loss of the activity of P450c11 is not accompanied by loss of steroid synthesis, indicating that P450scc continues to function with little or no damage under the same conditions.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Hornsby and Crivello, 1983

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    • cites Hornsby, 1980, 1989

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    Interpretationreasoning
    § Protective Mechanisms to Minimize ROS Production and Damage

    Cholesterol supply is regulated by 'on-off' switch type mechanisms, while NADPH synthesis is regulated by mechanisms that function as a graded rheostat.

    “While cholesterol supply is regulated by 'on-off' switch type mechanisms, NADPH synthesis is regulated by mechanisms that function as a graded rheostat.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    In bovine corpora lutea, a low but significant correlation was observed between mitochondrial P450 system enzymes and a cytochrome oxidase subunit.

    “In bovine corpora lutea, a low but significant correlation was observed between mitochondrial P450 system enzymes and a cytochrome oxidase subunit (Hanukoglu and Hanukoglu, 1986).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Hanukoglu and Hanukoglu, 1986

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    Premisecitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    The rate of mitochondrial ROS generation is related to the level of oxidative damage to mtDNA and is inversely correlated with maximum longevity in higher vertebrates.

    “The rate of mitochondrial ROS generation is related to the level of oxidative damage to mtDNA and is inversely correlated with maximum longevity in higher vertebrates (Barja, 2004).”
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    • cites Barja, 2004

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    Premisecitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    In the placenta, a different START protein (MLN64) is involved in the transport of cholesterol to the mitochondria.

    “In the placenta, a different START protein (MLN64) is involved in the transport of cholesterol to the mitochondria (Tuckey, 2005).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Tuckey, 2005

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  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Interpretationcitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    If these findings reflect normal physiological status, then adrenodoxin may be a source of ROS in the absence of steroid metabolism.

    “If these findings reflect normal physiological status, then adrenodoxin may be a source of ROS in absence of steroid metabolism.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: Cellular metabolism could have changed within minutes after induction of anesthesia and prior to removal of the adrenal.

  • May combine two claims.

    Premisecitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    Chronic in vivo administration of ACTH in rats reduces plasma aldosterone, down-regulates CYP11B2 mRNA, and reduces P450aldo activity.

    “Chronic in vivo administration of ACTH in rats was observed to reduce plasma aldosterone, down-regulate CYP11B2 mRNA, and reduce P450aldo activity (Lehoux et al., 1998; Suwa et al., 2000).”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Lehoux et al., 1998

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    • cites Suwa et al., 2000

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    Premisecitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    Chronic ACTH administration in rats increased Mn-SOD expression, but decreased glutathione peroxidase mRNA in the adrenal capsules.

    “Chronic ACTH administration in rats increased Mn-SOD expression, but decreased glutathione peroxidase mRNA in the adrenal capsules (Raza et al., 2005; Suwa et al., 2000).”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Raza et al., 2005

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    • cites Suwa et al., 2000

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    Premisecitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    In sheep corpora lutea, cytosolic Cu-Zn-SOD, mitochondrial Mn-SOD, and glutathione peroxidase activities rise while nitric oxide synthase decreases during the luteal phase.

    “In sheep corpora lutea, cytosolic Cu-Zn-SOD, mitochondrial Mn-SOD, and glutathione peroxidase activities rise while nitric oxide synthase (NOS) decreases during the luteal phase (Al-Gubory et al., 2005).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Al-Gubory et al., 2005

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  • Classified as probably not a substantial claim.

    Premisecitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    The effect of silibinin is presumably due to the antioxidant property of the drug.

    “The addition of an antioxidant drug, silibinin, at a low dose, potentiated ACTH-stimulated secretion of corticosteroids in hyperplastic adrenocortical cells, leading the authors to conclude that the effect of silibinin is presumably due to the antioxidant property of the drug (Racz et al., 1990).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Racz et al., 1990

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    Interpretationcitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    At the stage of luteolysis, free radicals could play a functional role in apoptotic cell death and contribute to regression of the corpus luteum.

    “In contrast, at the stage of luteolysis, free radicals could play a functional role in apoptotic cell death and contribute to regression of corpus luteum (Behrman et al., 2001; Foyouzi et al., 2005; Niswender et al., 2000).”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites Behrman et al., 2001

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    • cites Foyouzi et al., 2005

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    • cites Niswender et al., 2000

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    Premisecitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    In cultured ovarian cancer cells, ROS stress induced Mn-SOD expression; suppression of Mn-SOD expression by siRNA caused an increase in superoxide and promoted cell proliferation in vitro and tumor growth in vivo.

    “In cultured ovarian cancer cells, ROS stress induced Mn-SOD expression; suppression of Mn-SOD expression by siRNA caused an increase in superoxide and promoted cell proliferation in vitro and tumor growth in vivo (Hu et al., 2005).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Hu et al., 2005

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    Premisenone given
    § Protective Mechanisms to Minimize ROS Production and Damage

    During the luteal phase, the increase in progesterone secretion reflects proliferation of steroidogenic cells and a major increase in expression of steroidogenic enzymes, primarily P450scc.

    “During the luteal phase, the increase in progesterone secretion reflects proliferation of steroidogenic cells and a major increase in the expression of the steroidogenic enzymes, primarily mitochondrial cholesterol side-chain cleavage P450scc.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    In rats, vitamin A depletion causes a secondary deficiency of ascorbic acid in the adrenal, leading to adrenocortical degeneration, and ascorbate supplement prevents degeneration.

    “In rats, vitamin A depletion causes a secondary deficiency of ascorbic acid in the adrenal, leading to adrenocortical degeneration, and ascorbate supplement prevents degeneration (Gruber et al., 1976).”
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    • cites Gruber et al., 1976

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    Premisecitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    ACTH stimulated cortisol secretion from the guinea pig adrenal is accompanied by a decrease in the levels of ascorbate in the adrenal, but not in other tissues or plasma.

    “ACTH stimulated cortisol secretion from the guinea pig adrenal is accompanied by a decrease in the levels of ascorbate in the adrenal, but not in other tissues or plasma (Laney et al., 1990).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Laney et al., 1990

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    Premisecitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    If there is no pregnancy, the corpus luteum regresses by an apoptotic process.

    “If there is no pregnancy, then corpus luteum regresses by an apoptotic process (McCracken et al., 1999; Niswender, 2002; Tilly, 1996; Zheng et al., 1994).”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites McCracken et al., 1999

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    • cites Niswender, 2002

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    • cites Tilly, 1996

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  • May combine two claims.

    Interpretationreasoning
    § Protective Mechanisms to Minimize ROS Production and Damage

    At the final stage of corpus luteum, antioxidant levels would be expected to decrease, allowing ROS to contribute to apoptosis and regression of the corpus luteum.

    “Thus, at the final stage of corpus luteum, antioxidant levels would be expected to decrease, allowing ROS to contribute to apoptosis and regression of the corpus luteum.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationnone given
    § Protective Mechanisms to Minimize ROS Production and Damage

    The findings for small antioxidant molecules show that their levels change significantly during corpus luteum development, yet there does not appear to be a consistent pattern indicating complex functional and regulatory roles for these.

    “The findings for the small antioxidant molecules show that the levels of these antioxidants change significantly during corpus luteum development, yet there does not appear to be a consistent pattern indicating complex functional and regulatory roles for these.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning
    § Protective Mechanisms to Minimize ROS Production and Damage

    The findings for antioxidant enzymes SOD, catalase, and glutathione peroxidase are generally consistent with the expected trends.

    “The findings reviewed in the following paragraphs for the antioxidant enzymes SOD, catalase, and glutathione peroxidase are, in general, consistent with these expected trends.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    While Cu-Zn-SOD activity and mRNA dropped during luteal regression, Mn-SOD activity and mRNA showed further increases, suggesting that these two enzymes play different roles in regulating luteal function.

    “However, while Cu-Zn-SOD activity and mRNA dropped during luteal regression, Mn-SOD activity and mRNA showed further increases, suggesting that these two enzymes play different roles in regulating luteal function (Sugino et al., 2000).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Sugino et al., 2000

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    Premisecitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    After ovulation, the follicle enters the luteal phase, during which granulosa and theca cells proliferate to form corpus luteum, and synthesize and secrete progesterone at high levels to prepare the uterus for implantation.

    “After ovulation, the follicle enters the luteal phase, during which granulosa and theca cells of the follicle proliferate to form corpus luteum, and synthesize and secrete progesterone at high levels (nmol/L range) to prepare the uterus for implantation.”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites McCracken et al., 1999

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    • cites Niswender, 2002

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    • cites Tilly, 1996

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    Premisecitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    In bovine corpus luteum, the levels of ascorbate increase during the luteal phase and then drop during regression.

    “In bovine corpus luteum, the levels of ascorbate increase during the luteal phase and then drop during regression (Rapoport et al., 1998).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Rapoport et al., 1998

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    Premisecitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    In rat ovary, follicular development was associated with an increase in vitamin A and luteal regression was associated with an increase in both vitamins A and E.

    “In rat ovary, follicular development was associated with an increase in vitamin A and luteal regression was associated with an increase in both vitamins A and E (Aten et al., 1992).”
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    • cites Aten et al., 1992

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    Premisecitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    With aging in males, the capacity for testosterone biosynthesis declines as a consequence of multiple alterations in the hypothalamic-pituitary axis and Leydig cell steroidogenic system.

    “With aging in males, the capacity for testosterone biosynthesis declines as a consequence of multiple alterations in the hypothalamic-pituitary axis and Leydig cell steroidogenic system (Wang and Stocco, 2005; Zirkin and Chen, 2000).”
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    • cites Wang and Stocco, 2005

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    • cites Zirkin and Chen, 2000

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    Premisecitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    Exogenously added H2O2 inhibited both cAMP-stimulated progesterone production and StAR protein expression in MA-10 tumor Leydig cells, but did not affect P450scc enzyme levels.

    “Exogenously added H 2 O2 was observed to inhibit both cAMP-stimulated progesterone production and StAR protein expression in MA-10 tumor Leydig cells, but did not effect P450scc enzyme levels (Diemer et al., 2003).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Diemer et al., 2003

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    Premisecitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    Leydig cells develop and reach their full steroidogenic potential after puberty.

    “The Leydig cells develop and reach their full steroidogenic potential after puberty (Cummings and Kavlock, 2004).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Cummings and Kavlock, 2004

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  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Interpretationnone given
    § SUMMARY

    Steroidogenic cells have a full spectrum of antioxidant molecules, which in some tissues reach the highest level in the body.

    “Steroidogenic cells have a full spectrum of antioxidant molecules, which in some tissues reach the highest level in the body.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    In bovine corpus luteum, vitamin A concentration is 3.5-5.5 μg/g tissue.

    “| Vitamin A | Bovine | C. luteum | 3.5-5.5 μ g/g tissue | (Haliloglu et al., 2002) |”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Haliloglu et al., 2002

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    In rat adrenal, α-tocopherol concentration is 30-50 μg/g tissue.

    “| α -tocopherol | Rat | Adrenal | 30-50 μ g/g tissue | (Burczynski et al., 2001) |”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Burczynski et al., 2001

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Premisecitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    Findings of some studies provide evidence for the hypothesis that ROS produced as a by-product of steroidogenesis may be responsible for age-related decline in testosterone production by Leydig cells.

    “The findings of some studies provide evidence for the hypothesis that ROS produced as a by-product of steroidogenesis may be responsible for age-related decline in testosterone production by the Leydig cells (Chen and Zirkin, 1999; Zirkin and Chen, 2000).”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Chen and Zirkin, 1999

      Not checked in the free run.

    • cites Zirkin and Chen, 2000

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    In rat adrenal, ascorbate concentration is 2.5-5 mg/g tissue.

    “| Ascorbate | Rat | Adrenal | 2.5-5 mg/g tissue | (Mitani et al., 2005) |”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Mitani et al., 2005

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    Vitamin C is taken up into the cell by specific transporter proteins SVCT1 and SVCT2.

    “Vitamin C is taken up into the cell by specific transporter proteins SVCT1 and SVCT2 (Wilson, 2005).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Wilson, 2005

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    In bovine corpus luteum, α-tocopherol concentration is 1-132 μg/g tissue.

    “| α -tocopherol | Bovine | C. luteum | 1-132 μ g/g tissue | (Rapoport et al., 1998) (Schweigert, 2003) |”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Rapoport et al., 1998

      Not checked in the free run.

    • cites Schweigert, 2003

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    Leydig cells in the interstitium, located between the seminiferous tubules of the testis, are the major source of androgenic steroids.

    “The Leydig cells in the interstitium, located in between the seminiferous tubules of the testis, are the major source of androgenic steroids (Payne and Hales, 2004; Zirkin and Chen, 2000).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Payne and Hales, 2004

      Not checked in the free run.

    • cites Zirkin and Chen, 2000

      Not checked in the free run.

  • May combine two claims.

    Premisecitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    Both adrenodoxin and P450 are metal carrying proteins that generate free radicals during electron transfer, making these proteins prone to metal-catalyzed oxidation and crosslinking reactions.

    “The fact that both adrenodoxin and P450 are metal carrying proteins that generate free radicals during electron transfer make these proteins prone to metal-catalyzed oxidation and crosslinking reactions (Liu et al., 2004; Stadtman, 1993).”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Liu et al., 2004

      Not checked in the free run.

    • cites Stadtman, 1993

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    In bovine corpus luteum, ascorbate concentration is 4-10 mg/g tissue.

    “| Ascorbate | Bovine | C. luteum | 4-10 mg/g tissue | (Rapoport et al., 1998) |”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Rapoport et al., 1998

      Not checked in the free run.

  • May combine two claims.

    Premisecitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    The addition of β-carotene at levels found in bovine serum, but not α-tocopherol or ascorbic acid, inhibited the cross-linking.

    “The addition of β -carotene at levels found in bovine serum, but not α -tocopherol or ascorbic acid, inhibited the cross-linking (Young et al., 1995).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Young et al., 1995

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    In bovine corpus luteum, β-carotene concentration is 6-216 μg/g tissue.

    “| β -carotene | Bovine | C. luteum | 6-216 μ g/g tissue | (Arikan and Rodway, 2001) (Haliloglu et al., 2002) |”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Arikan and Rodway, 2001

      Not checked in the free run.

    • cites Haliloglu et al., 2002

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Protective Mechanisms to Minimize ROS Production and Damage

    The testis has small antioxidants.

    “and small antioxidants (Chen et al., 2005; Livera et al., 2002).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Chen et al., 2005

      Not checked in the free run.

    • cites Livera et al., 2002

      Not checked in the free run.

54 of 54

  • The paper relies on this without support.

    AdR is ubiquitously expressed in different cells.

    “AdR is ubiquitously expressed in different cells.”

  • The paper relies on this without support.

    Mitochondrial P450 system electron transfer proteins are ubiquitously expressed in different tissues.

    “Yet, the mitochondrial P450 system electron transfer proteins are ubiquitously expressed in different tissues.”

  • The paper relies on this without support.

    The cells used in adrenodoxin overexpression studies are non-steroidogenic cells.

    “This conclusion may be questioned, noting that the cells used in overexpression studies are non-steroidogenic cells.”

  • The paper relies on this without support.

    Cellular metabolism could have changed within minutes after induction of anesthesia and prior to removal of the adrenal.

    “This interpretation requires a caveat that cellular metabolism could have changed within minutes after induction of anesthesia and prior to the removal of the adrenal.”
4 of 4

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • Electron transfer forms a high-affinity complex between Erg11 and Ncp1.

    “This electron transfer forms a high-affinity complex between the proteins17.”

    From Impairing the interaction between Erg11 and cytochrome P450 reductase Ncp1 enhances azoles’ antifungal activities (2025) · cites this paper as [17]

    The ‘Electron Transfer in Mitochondrial P450 Systems’ section (page unavailable) says redox partners form transient high-affinity complexes and that electron transfer depends on a complex forming. It does not identify Erg11 and Ncp1 or establish that electron transfer itself forms their complex. (LLM, conf=0.86)

    Experimental — accuracy not yet measured

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Related

Authors
Hanukoglu, I.
Affiliations
Ariel University (IL)
Corresponding author
Hanukoglu, Israel
ORCID
Hanukoglu, Israel
Venue
Drug Metabolism Reviews
Publisher
Informa UK Limited
Published
2006-01
Volume
38
Issue
1-2
Pages
171-196
ISSN
  • 0360-2532 (ISSN-L)
  • 1097-9883
DOI
10.1080/03602530600570040
OpenAlex
W2038758189
Semantic Scholar
e47d7fe29aa2374a673ae5d2f21edb3fbd816884
Cited by
293
References
150
Citations by year
2026: 15 · 2025: 16 · 2024: 18 · 2023: 18 · 2022: 14 · 2021: 20 · 2020: 16 · 2019: 10 · 2018: 11 · 2017: 17 · 2016: 12 · 2015: 13 · 2014: 18 · 2013: 11 · 2012: 22
FWCI
1.28
Type
journal article
Language
en
Open access
closed
Locations
  • Drug Metabolism Reviews (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Health Sciences › Medicine › Biochemistry › Antioxidant Activity and Oxidative Stress
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Redox biology and oxidative stress
  • Physical Sciences › Chemistry › Inorganic Chemistry › Metal-Catalyzed Oxygenation Mechanisms
Keywords
mitochondrial cytochrome P450, steroidogenesis, reactive oxygen species, oxidative stress, adrenodoxin, adrenodoxin reductase, superoxide production, antioxidant enzymes, superoxide dismutase, catalase, glutathione peroxidase, beta-carotene, alpha-tocopherol, vitamin C, Leydig cells, corpus luteum, ovary, steroidogenic cells
MeSH terms
Adrenodoxin, Animals, Antioxidants, Cytochrome P-450 Enzyme System, Electron Transport, Endocrine Glands, Humans, Mitochondria, NADP, Steroids, Reactive Oxygen Species

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