maillol
Member
- Joined
- Oct 28, 2019
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Some notes on Cytochrome P450 enzymes
Exposure to cigarette smoke subjects tissues to increased reactive oxygen species, which can induce cytochrome P450 enzymes and result in the degradation of retinoic acid, the bioactive form of vitamin A.
Alcohol acts as a competitive inhibitor of vitamin A oxidation to retinoic acid involving alcohol dehydrogenases and acetaldehyde dehydrogenases, induces cytochrome P450 enzymes (particularly CYP2E1) that degrade retinol and retinoic acid, and alters retinoid homeostasis by increasing vitamin A mobilization from liver to extrahepatic tissues.
From Alcohol and Tobacco Smoke in Retinoid Metabolism and Signaling: Implications for Carcinogenesis
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CYP2E1 also degrades retinoic acid and retinol to polar metabolites. Metabolism of retinoic acid not only results in the loss of retinoic acid promoting carcinogenesis through an increase in cell proliferation and dedifferentiation but also in generation of polar metabolites with apoptotic properties.
From <The role of cytochrome P450 2E1 in ethanol-mediated carcinogenesis - PubMed>
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Niacin (nicotinic acid) and its form – niacinamide (nicotinamide), collectively called as vitamin B3 inhibits CYP2E1
From <List of cytochrome P450 modulators - Wikipedia>
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It is concluded that in addition to CYP1A1 and CYP3A, CYP26 may be the main CYP enzyme responsible for the metabolism of all-trans-RA in enterocytes.
From https://pubmed.ncbi.nlm.nih.gov/11082432/
Inducers of CYP1A1
• Certain foods (e.g., broccoli, cauliflower, brussels sprouts, chargrilled meat)
• Insulin
• Methylcholanthrene
• Modafinil
• Nafcillin
• Omeprazole
• Phenytoin
• beta-Naphthoflavone
• Tobacco
From <List of cytochrome P450 modulators - Wikipedia>
That Wikipedia link above has a large list of inhibitors and inducers for the various P450 enzymes most of which seem to be involved in retinoid metabolism in some way. A noteworthy inhibitor is caffeine and as mentioned above, niacinamide. My thinking is that inducing these enzymes might help with eliminating vitamin A and it may also be a good idea to avoid inhibitors like niacinamide and grapefruit.
Exposure to cigarette smoke subjects tissues to increased reactive oxygen species, which can induce cytochrome P450 enzymes and result in the degradation of retinoic acid, the bioactive form of vitamin A.
Alcohol acts as a competitive inhibitor of vitamin A oxidation to retinoic acid involving alcohol dehydrogenases and acetaldehyde dehydrogenases, induces cytochrome P450 enzymes (particularly CYP2E1) that degrade retinol and retinoic acid, and alters retinoid homeostasis by increasing vitamin A mobilization from liver to extrahepatic tissues.
From Alcohol and Tobacco Smoke in Retinoid Metabolism and Signaling: Implications for Carcinogenesis
-----------------------------------------
CYP2E1 also degrades retinoic acid and retinol to polar metabolites. Metabolism of retinoic acid not only results in the loss of retinoic acid promoting carcinogenesis through an increase in cell proliferation and dedifferentiation but also in generation of polar metabolites with apoptotic properties.
From <The role of cytochrome P450 2E1 in ethanol-mediated carcinogenesis - PubMed>
-----------------------------------------
Niacin (nicotinic acid) and its form – niacinamide (nicotinamide), collectively called as vitamin B3 inhibits CYP2E1
From <List of cytochrome P450 modulators - Wikipedia>
-----------------------------------------
It is concluded that in addition to CYP1A1 and CYP3A, CYP26 may be the main CYP enzyme responsible for the metabolism of all-trans-RA in enterocytes.
From https://pubmed.ncbi.nlm.nih.gov/11082432/
Inducers of CYP1A1
• Certain foods (e.g., broccoli, cauliflower, brussels sprouts, chargrilled meat)
• Insulin
• Methylcholanthrene
• Modafinil
• Nafcillin
• Omeprazole
• Phenytoin
• beta-Naphthoflavone
• Tobacco
From <List of cytochrome P450 modulators - Wikipedia>
That Wikipedia link above has a large list of inhibitors and inducers for the various P450 enzymes most of which seem to be involved in retinoid metabolism in some way. A noteworthy inhibitor is caffeine and as mentioned above, niacinamide. My thinking is that inducing these enzymes might help with eliminating vitamin A and it may also be a good idea to avoid inhibitors like niacinamide and grapefruit.