Component
SRR-alpha-tocopherol
The 2S,4′R,8′R stereoisomer of free alpha-tocopherol.
4 recorded relationships. Experimental role, claim status and evidence remain attached to each record.
How nutrients influence it
Every nutrient with a recorded effect on this component, credited to the nutrient that acted rather than the chapter that recorded it. Open a nutrient to see the findings and the conditions they were measured under.
Other things that act on it
Enzymes, hormones, genes, and other components with a recorded effect. These are not nutrients, so they do not count toward the arrows above. Each finding names the chapter that recorded it.
How nutrients reach it in more than one step
Chains of two or more recorded steps that end here, grouped by the nutrient they start from. Each step is a separate finding, so a chain is a route a mechanism could take, not proof that it does.
Tracing routes…
What it does
Every recorded relationship this component is part of, grouped by its role. Plain wording comes first; the technical statement follows.
What acts on it
In a rat alpha-TTP membrane-transfer competition assay, SRR-alpha-tocopherol had relative affinity 10.5% of RRR-alpha-tocopherol (100%).
Experimental context and source evidence
- cross_nutrient
- false
- experimental_model
- Purified rat liver protein and membrane-transfer competition
- exposure
- 37 °C, 30 min; Table 1 competition-derived affinity.
- limitations
- Relative transfer competition, not a direct Kd or human clinical efficacy ratio.
- nutrient_topic
- Vitamin E research collection; topical membership is not evidence of a direct dietary effect. · Vitamin E
- organism
- Rattus norvegicus
- plain_language
- Rat alpha-TTP distinguished this form from RRR-alpha-tocopherol.
- primary_references
- [hosomi1997] Affinity for alpha-tocopherol transfer protein as a determinant of the biological activities of vitamin E analogs. (1997). https://pubmed.ncbi.nlm.nih.gov/9199513/ DOI: 10.1016/s0014-5793(97)00499-7
- tissue_or_cell_type
- Liver protein/liposomes
Vitamin E: transport, membrane protection and nutrient interactions (2026-09-17) · lines 142–153
AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified rat liver protein and membrane-transfer competition · source_derived_draft · unverified_draft
### ve-transport-rat-ttp-affinity-srr-alpha-tocopherol In a rat alpha-TTP membrane-transfer competition assay, SRR-alpha-tocopherol had relative affinity 10.5% of RRR-alpha-tocopherol (100%). Condition category: normal nutrient_topic: Vitamin E research collection; topical membership is not evidence of a direct dietary effect. plain_language: Rat alpha-TTP distinguished this form from RRR-alpha-tocopherol. organism: Rattus norvegicus tissue_or_cell_type: Liver protein/liposomes experimental_model: Purified rat liver protein and membrane-transfer competition limitations: Relative transfer competition, not a direct Kd or human clinical efficacy ratio. exposure: 37 °C, 30 min; Table 1 competition-derived affinity. cross_nutrient: false [hosomi1997] Affinity for alpha-tocopherol transfer protein as a determinant of the biological activities of vitamin E analogs. (1997). https://pubmed.ncbi.nlm.nih.gov/9199513/ DOI: 10.1016/s0014-5793(97)00499-7
Complete structured claim and evidence
Where it participates (unsigned role)
Alpha-tocopherol did not increase phylloquinone omega-hydroxylation in CYP4F2 microsomes; the study reported a slight decrease in apparent phylloquinone Vmax.
Experimental context and source evidence
- cross_nutrient
- true
- experimental_model
- Recombinant human CYP4F2 co-substrate kinetics
- exposure
- Labeled phylloquinone 0–50 µM with RRR-alpha-tocopherol 0–50 µM or SRR-alpha-tocopherol 0–100 µM; 30 min, 37 °C, 1 mM NADPH.
- limitations
- Does not exclude other mechanisms of vitamin E–K interaction in animals or humans.
- nutrient_topic
- Vitamin E research collection; topical membership is not evidence of a direct dietary effect. · Vitamin E
- organism
- Human protein in insect microsomes
- plain_language
- This assay did not support faster vitamin K1 breakdown caused by alpha-tocopherol.
- primary_references
- [farley2013] ω-Hydroxylation of phylloquinone by CYP4F2 is not increased by α-tocopherol. (2013). https://pubmed.ncbi.nlm.nih.gov/23650179/ DOI: 10.1002/mnfr.201200797
- tissue_or_cell_type
- Microsomal enzyme preparation
Vitamin E: transport, membrane protection and nutrient interactions (2026-09-17) · lines 467–478
AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human CYP4F2 co-substrate kinetics · source_derived_draft · unverified_draft
### ve-transport-alpha-does-not-activate-k1-catabolism Alpha-tocopherol did not increase phylloquinone omega-hydroxylation in CYP4F2 microsomes; the study reported a slight decrease in apparent phylloquinone Vmax. Condition category: normal nutrient_topic: Vitamin E research collection; topical membership is not evidence of a direct dietary effect. plain_language: This assay did not support faster vitamin K1 breakdown caused by alpha-tocopherol. organism: Human protein in insect microsomes tissue_or_cell_type: Microsomal enzyme preparation experimental_model: Recombinant human CYP4F2 co-substrate kinetics limitations: Does not exclude other mechanisms of vitamin E–K interaction in animals or humans. exposure: Labeled phylloquinone 0–50 µM with RRR-alpha-tocopherol 0–50 µM or SRR-alpha-tocopherol 0–100 µM; 30 min, 37 °C, 1 mM NADPH. cross_nutrient: true [farley2013] ω-Hydroxylation of phylloquinone by CYP4F2 is not increased by α-tocopherol. (2013). https://pubmed.ncbi.nlm.nih.gov/23650179/ DOI: 10.1002/mnfr.201200797
Complete structured claim and evidenceAfter equal oral labeled RRR- and SRR-alpha-tocopheryl acetate, the human chylomicron fraction contained similar concentrations of the two tocopherol stereoisomers.
Experimental context and source evidence
- cross_nutrient
- false
- experimental_model
- Human stable-isotope oral study with lipoprotein fractionation
- exposure
- Four subjects received equal paired doses of labeled RRR and SRR acetate ester with breakfast: 40, 50, 75 or 75 mg of each ester; samples through 76 hours.
- limitations
- Small tracer study; fraction enrichment alone does not prove the molecular sorting step or clinical benefit.
- nutrient_topic
- Vitamin E research collection; topical membership is not evidence of a direct dietary effect. · Vitamin E
- organism
- Homo sapiens
- plain_language
- Early chylomicron delivery did not strongly distinguish the two tested stereoisomers.
- primary_references
- [traber1990] RRR- and SRR-alpha-tocopherols are secreted without discrimination in human chylomicrons, but RRR-alpha-tocopherol is preferentially secreted in very low density lipoproteins. (1990). https://pubmed.ncbi.nlm.nih.gov/2351872/ DOI: 10.1016/s0022-2275(20)42836-6
- tissue_or_cell_type
- Plasma chylomicron or VLDL fractions
Vitamin E: transport, membrane protection and nutrient interactions (2026-09-17) · lines 298–309
AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human stable-isotope oral study with lipoprotein fractionation · source_derived_draft · unverified_draft
### ve-transport-chylomicron-stereoisomers After equal oral labeled RRR- and SRR-alpha-tocopheryl acetate, the human chylomicron fraction contained similar concentrations of the two tocopherol stereoisomers. Condition category: normal nutrient_topic: Vitamin E research collection; topical membership is not evidence of a direct dietary effect. plain_language: Early chylomicron delivery did not strongly distinguish the two tested stereoisomers. organism: Homo sapiens tissue_or_cell_type: Plasma chylomicron or VLDL fractions experimental_model: Human stable-isotope oral study with lipoprotein fractionation limitations: Small tracer study; fraction enrichment alone does not prove the molecular sorting step or clinical benefit. exposure: Four subjects received equal paired doses of labeled RRR and SRR acetate ester with breakfast: 40, 50, 75 or 75 mg of each ester; samples through 76 hours. cross_nutrient: false [traber1990] RRR- and SRR-alpha-tocopherols are secreted without discrimination in human chylomicrons, but RRR-alpha-tocopherol is preferentially secreted in very low density lipoproteins. (1990). https://pubmed.ncbi.nlm.nih.gov/2351872/ DOI: 10.1016/s0022-2275(20)42836-6
Complete structured claim and evidenceAfter equal oral labeled RRR- and SRR-alpha-tocopheryl acetate, human VLDL became enriched in RRR-alpha-tocopherol relative to SRR-alpha-tocopherol by 11 hours.
Experimental context and source evidence
- cross_nutrient
- false
- experimental_model
- Human stable-isotope oral study with lipoprotein fractionation
- exposure
- Four subjects received equal paired doses of labeled RRR and SRR acetate ester with breakfast: 40, 50, 75 or 75 mg of each ester; samples through 76 hours.
- limitations
- Small tracer study; fraction enrichment alone does not prove the molecular sorting step or clinical benefit.
- nutrient_topic
- Vitamin E research collection; topical membership is not evidence of a direct dietary effect. · Vitamin E
- organism
- Homo sapiens
- plain_language
- A later lipoprotein fraction favored the RRR form.
- primary_references
- [traber1990] RRR- and SRR-alpha-tocopherols are secreted without discrimination in human chylomicrons, but RRR-alpha-tocopherol is preferentially secreted in very low density lipoproteins. (1990). https://pubmed.ncbi.nlm.nih.gov/2351872/ DOI: 10.1016/s0022-2275(20)42836-6
- tissue_or_cell_type
- Plasma chylomicron or VLDL fractions
Vitamin E: transport, membrane protection and nutrient interactions (2026-09-17) · lines 311–322
AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human stable-isotope oral study with lipoprotein fractionation · source_derived_draft · unverified_draft
### ve-transport-vldl-stereoisomers After equal oral labeled RRR- and SRR-alpha-tocopheryl acetate, human VLDL became enriched in RRR-alpha-tocopherol relative to SRR-alpha-tocopherol by 11 hours. Condition category: normal nutrient_topic: Vitamin E research collection; topical membership is not evidence of a direct dietary effect. plain_language: A later lipoprotein fraction favored the RRR form. organism: Homo sapiens tissue_or_cell_type: Plasma chylomicron or VLDL fractions experimental_model: Human stable-isotope oral study with lipoprotein fractionation limitations: Small tracer study; fraction enrichment alone does not prove the molecular sorting step or clinical benefit. exposure: Four subjects received equal paired doses of labeled RRR and SRR acetate ester with breakfast: 40, 50, 75 or 75 mg of each ester; samples through 76 hours. cross_nutrient: false [traber1990] RRR- and SRR-alpha-tocopherols are secreted without discrimination in human chylomicrons, but RRR-alpha-tocopherol is preferentially secreted in very low density lipoproteins. (1990). https://pubmed.ncbi.nlm.nih.gov/2351872/ DOI: 10.1016/s0022-2275(20)42836-6
Complete structured claim and evidence
The events it takes part in
A mechanism often involves more than two components. These are the full events, with every participant and its role.
Situations it appears in
Low-supply and faulty-machinery situations recorded in the chapters where this component plays a part.
In the sources
Preserved passages that mention this component, quoted exactly. Open one to read it in context.
Open hypotheses
Proposed ideas that involve this component. They are labeled as hypotheses and do not change any recorded statement.
This is a research prototype built from draft material. It is not medical advice, and its statements still await verification against the original studies.