Biological Activity

Bioactivity / Mechanism

FK506 (tacrolimus) inhibits cellular calcineurin activity in Jurkat T cells. Rapamycin antagonism is consistent with an FKBP-mediated action. In activated cells, reported IC50 values were 0.4 nM for calcineurin activity and approximately 0.2 nM for IL-2 production. These are cellular assay endpoints, not binding affinities or treatment recommendations. [1]

Literature-reported observations and conditions; not Adooq-tested protocols or general treatment recommendations.

Target & Activity

Target	Activity	Value
FKBP12 (T cells)

Cellular Effect

Cell Line	Activity	Value	Description	Reference
B-cell	IC50	1.6 ng/mL	Immunosuppressive activity in BALB/c mouse splenic B lymphocytes assessed as inhibition of LPS-induced cell proliferation after 72 hrs by MTT assay	[PMID: 14738397]
CD4+ve Th	IC50	0.034 nM	Immunosuppressive activity in C57BL/6J mouse CD4+ve T cells assessed as inhibition of CD3/CD28-stimulated CD4+ve T cell proliferation incubated for 72 hrs by CellTrace-violet staining based flow cytometry analysis	[PMID: 33534559]
Jurkat	IC50	0.056 nM	Inhibition of calcineurin in human Jurkat cells assessed as inhibition of NFAT-mediated IL-2 production after 8 hrs by beta-lactamase reporter gene assay	10.1039/C2MD20266B
Jurkat	IC50	0.19 nM	Inhibitory activity against IL-2 receptor in human T-cell jurkat cell line stimulated by phytohemagglutininin and phorbol myristate acetate	[PMID: 15369399]
Jurkat	IC50	0.36 μM	Immunosuppressive activity in PMA/ionomycin stimulated human Jurkat T cells assessed as suppression of IL2 production pretreated for 15 to 30 mins followed by PMA/ionomycin addition measured after 18 to 20 hrs by ELISA	[PMID: 28412204]
Jurkat	IC50	5.8 μM	Anti-inflammatory activity in PMA/ionomycin stimulated human Jurkat T cells assessed as reduction in IL-2 secretion preincubated for 20 mins followed by PMA/ionomycin stimulation measured after 12 hrs by ELISA	[PMID: 28509552]
RBL-2H3	IC50	0.25 nM	Inhibition of TNF-alpha production in rat RBL2H3 cells after 16 hrs by ELISA	[PMID: 23791076]
RBL-2H3	IC50	0.25 nM	Antiinflammatory activity in rat RBL2H3 cells assessed as inhibition of DNP-BSA-induced TNF-alpha production preincubated for 15 mins prior DNP-BSA challenge measured after 30 mins by ELISA	[PMID: 22410084]
T-cell	IC50	0.18 nM	Agonistic activity in a murine splenic T-cell proliferation assay was calculated by measurement of [3H]thymidine uptake relative to control	10.1016/S0960-894X(01)81248-8
T-cell	IC50	1.5 x 10	Immunosuppressive activity in BALB/c mouse splenic T lymphocytes assessed as inhibition of Con A-induced cell proliferation after 72 hrs by MTT assay	[PMID: 14738397]
U-251	IC50	13.8 nM	Inhibition of SAP130 in VEGF-stimulated human U251 cells by PLAP reporter gene assay	[PMID: 17643112]

11 records · Scroll to view more

In Vitro Studies

FK506 pretreatment at 10–500 nM improved survival of PC12, Neuro2A and SHSY-5Y cells challenged with hydrogen peroxide. R3T3 fibroblasts were not protected under the tested conditions, demonstrating a cell-type limit to this response. [2]

Cellular calcineurin inhibition and rapamycin antagonism

Cell-based study · Human Jurkat J77 T cells; phosphatase activity assayed in lysates after cellular drug exposure [1]

FK506 inhibited calcium-dependent, okadaic-acid-insensitive phosphatase activity. Rapamycin alone had no effect and excess rapamycin prevented FK506 inhibition, consistent with an FKBP-mediated effect. These experiments test cellular target engagement; they do not directly measure complex binding affinity.

Measured endpoints — not treatment concentrations
Endpoint	Reported result	Reference
Calcineurin activity in lysates of FK506-treated Jurkat cells	IC50 approximately 0.5 nM	[1]
FK506-induced inhibition of calcineurin with excess rapamycin	Qualitative comparator result 1 μM rapamycin prevented FK506-mediated inhibition; rapamycin did not prevent CsA-mediated inhibition	[1]

Literature-Reported Treatment Conditions

Treatment concentration: 10 nM FK506 in Fig.2 bottom; concentration titration in Fig.3; 1 μM rapamycin in antagonism experiment
Exposure duration: 1 h drug exposure at 37°C before washing and lysis
Method: Cell treatment followed by radiolabeled RII phosphopeptide dephosphorylation assay
Vehicle: Ethanol; 1 μl stock added per 1 ml complete medium; ethanol control treated identically
Co-treatment: Rapamycin used as a separate comparator and as a competitive cotreatment, not a therapeutic combination
Reported limits: Biological replicate n and uncertainty for the dose-response IC50 are not specified in the read Results/caption.

Methods and source locations

Compound reported in the paper: FK506 (tacrolimus); Compound label in the paper: FK506

Evidence concerns the named research compound in this model and source formulation; it does not validate an Adooq lot.

pp.3687–3689, Cell Treatment and Lysis; Phosphatase Assay; Fig.2 bottom, Fig.3 and Results

Calcineurin activity in lysates of FK506-treated Jurkat cells: Authors’ reported estimate from cellular drug titration; phosphatase assay after wash/lysis — p.3688 Results; Fig.3 upper

FK506-induced inhibition of calcineurin with excess rapamycin: Cell pretreatment and lysate phosphatase assay — p.3688 Results; Fig.3 lower

Comparison of calcineurin and IL-2 inhibitory concentrations

Cell-based study · Human Jurkat J77 cells activated with OKT3 plus PMA [1]

In parallel experiments, FK506 inhibited cellular calcineurin activity and IL-2 production at subnanomolar concentrations. The concentration relationship supports a role for calcineurin in T-cell activation; it is not a biochemical binding constant.

Measured endpoints — not treatment concentrations
Endpoint	Reported result	Reference
Calcineurin activity in activated Jurkat cells	IC50 0.4 nM	[1]
IL-2 production after 24 h activation	IC50 approximately 0.2 nM	[1]

Literature-Reported Treatment Conditions

Treatment concentration: FK506 titration; endpoint IC50 values are recorded separately from treatment concentrations
Exposure duration: Shared cellular phosphatase method: 1 h drug exposure; IL-2 comparison: 24 h incubation
Method: Lysate phosphatase assay and IL-2-dependent CTLL-20 bioassay of culture supernatants
Vehicle: Ethanol control in shared Cell Treatment and Lysis method; medium/no-drug controls in Fig.4
Co-treatment: OKT3 plus PMA stimulation; CsA was a separate comparator
Reported limits: Biological replicate n and IC50 uncertainty are not given in the read Results/caption.

Methods and source locations

Compound reported in the paper: FK506 (tacrolimus); Compound label in the paper: FK506

Evidence concerns the named research compound in this model and source formulation; it does not validate an Adooq lot.

pp.3687,3689; Interleukin 2 Assay; Fig.4 and associated Results

Calcineurin activity in activated Jurkat cells: Authors’ reported cellular phosphatase IC50 — p.3689 Results; Fig.4 upper

IL-2 production after 24 h activation: CTLL-20 bioassay; authors’ text estimate — p.3689 Results; Fig.4 lower

Cell-type dependence of protection against oxidative injury

Cell-based study · PC12, Neuro2A and SHSY-5Y neuronal cell lines, with R3T3 fibroblasts as a non-neuronal comparator [2]

FK506 improved survival after hydrogen-peroxide challenge in the three neuronal cell lines. R3T3 fibroblasts were not protected. This survival experiment does not itself identify the pathway responsible for protection.

Measured endpoints — not treatment concentrations
Endpoint	Reported result	Reference
Survival of neuronal cell lines after oxidative challenge	Qualitative treatment response Protection at 10–500 nM FK506 in PC12, Neuro2A and SHSY-5Y	[2]
Survival of R3T3 fibroblasts after oxidative challenge	Negative result No protection by FK506 at the tested 10, 100 and 500 nM concentrations	[2]

Literature-Reported Treatment Conditions

Treatment concentration: 10, 100 and 500 nM FK506; 200 μM H2O2 challenge
Exposure duration: FK506 added 30 min before challenge; survival assessment time after H2O2 is not specified in the read Methods/Fig.1 caption
Method: Trypan blue exclusion with viable-cell counting
Vehicle: Appropriate vehicle at appropriate dilution used for controls; chemical identity not stated in the read Methods
Co-treatment: H2O2 is the injury stimulus; V-10,367 was a separate comparator, not cotreatment
Reported limits: Survival endpoint time and vehicle identity are not stated in the read shared Methods/Fig.1 caption. General statistics state 3–6 experiments; viable-cell counting states at least four independent sets, without group-specific n.

Methods and source locations

Compound reported in the paper: FK506 (tacrolimus); Compound label in the paper: FK506

Evidence concerns the named research compound in this model and source formulation; it does not validate an Adooq lot.

Methods: Treatment of cells, Trypan blue exclusion assay, Statistics; Results: Protection of neuronal cell lines, H2O2; Fig.1a

Survival of neuronal cell lines after oxidative challenge: Trypan blue exclusion; mean and s.e.mean; one-way repeated-measures ANOVA with Bonferroni post-test — Results: H2O2; Fig.1a

Survival of R3T3 fibroblasts after oxidative challenge: Same viability assay and matched injury/vehicle controls — Results: H2O2; Fig.1a

In Vivo Studies

In male Sprague Dawley rats, a single intraperitoneal FK506 dose 30 minutes before focal cerebral ischemia reduced cortical lesion volume at three days by 56% at 1 mg/kg and 58% at 10 mg/kg. Striatal ischemic damage was not reduced. These pretreatment results do not establish functional recovery or a post-injury treatment window. [3]

FK506 at 1 or 10 mg/kg did not reduce the tested excitotoxic lesions under the same intraperitoneal pretreatment schedule. MK801 reduced quinolinate and NMDA lesions; both drugs failed to reduce AMPA lesions. The results limit a general antiexcitotoxic interpretation of FK506 neuroprotection. [3]

FK506 pretreatment in focal cerebral ischemia

Animal study · Male Sprague Dawley rats, 300–370 g; endothelin-induced middle cerebral artery occlusion [3]

Intraperitoneal FK506 pretreatment reduced cortical ischemic lesion volume. It did not reduce striatal ischemic damage. The experiment measures histopathology at three days, not neurological function or long-term recovery.

Measured endpoints — not treatment concentrations
Endpoint	Reported result	Reference
Cortical ischemic damage volume relative to vehicle	Reported reduction 56% at 1 mg/kg; 58% at 10 mg/kg	[3]
Striatal ischemic damage volume	Negative result Neither FK506 dose reduced striatal ischemic damage; data not shown	[3]

Conditions shared by the study groups

Route: Intraperitoneal
Frequency: Single administration
Treatment course: 30 min before occlusion; endpoint day 3
Vehicle: 10% ethanol in 50 mM PBS containing 1% Tween 80

Study groups and reported outcomes
Group / dose	Comparator	Observed result	Reference
FK506 1 mg/kg	Matched FK506 vehicle; MK801 5 mg/kg was a separate positive control	Cortical ischemic damage reduced by 56%; no reduction in striatal ischemic damage (latter reported as data not shown)	[3]
FK506 10 mg/kg	Matched FK506 vehicle; separate MK801 positive control	Cortical ischemic damage reduced by 58%; no reduction in striatal ischemic damage (data not shown)	[3]

FK506 1 mg/kg: Model: Male Sprague Dawley rats with focal cerebral ischemia; Reported limits: Group-specific sample sizes are not provided; Fig.1 caption gives 5–12 animals per group across experiments.

FK506 10 mg/kg: Model: Male Sprague Dawley rats with focal cerebral ischemia; Reported limits: Group-specific sample sizes are not provided; Fig.1 caption gives 5–12 animals per group across experiments.

Methods and source locations

Compound reported in the paper: FK506 (tacrolimus); Compound label in the paper: FK506

Evidence concerns the named research compound in this model and source formulation; it does not validate an Adooq lot.

Methods: Materials, Induction of focal cerebral ischemia, Histopathological assessment; Results: Intraperitoneal drug administration; Fig.1 MCA occlusion–cortex panel

Cortical ischemic damage volume relative to vehicle: Blinded lesion-volume histopathology 3 d after MCAO; Fig.1 FK1 and FK10 both p < 0.01 versus vehicle — Results: Intraperitoneal drug administration; Fig.1 MCA occlusion–cortex

Striatal ischemic damage volume: Authors’ textual result; no numerical estimate available — Results: Intraperitoneal drug administration, first paragraph

FK506 1 mg/kg · Materials; lesion-model and histopathology Methods; Results: Intraperitoneal drug administration; Fig.1

FK506 10 mg/kg · Materials; lesion-model and histopathology Methods; Results: Intraperitoneal drug administration; Fig.1

Failure to reduce excitotoxic lesions

Animal study · Male Sprague Dawley rats, 280–340 g; quinolinate lesions in striatum, cortex and hippocampus, and NMDA/AMPA striatal lesions [3]

Under the intraperitoneal pretreatment protocol, FK506 did not reduce excitotoxic lesion volumes. MK801 reduced quinolinate and NMDA damage but did not reduce AMPA damage. This limits extrapolation of ischemic protection to a general antiexcitotoxic mechanism.

Measured endpoints — not treatment concentrations
Endpoint	Reported result	Reference
Excitotoxic brain lesion volume	Negative result No reduction with FK506 1 or 10 mg/kg in the tested quinolinate, NMDA and AMPA lesion models	[3]
Response of the positive-control comparator	Control result MK801 reduced quinolinate and NMDA lesions; neither MK801 nor FK506 reduced AMPA lesions	[3]

Conditions shared by the study groups

Route: Intraperitoneal
Frequency: Single administration
Treatment course: 30 min before lesion induction; endpoint day 3
Vehicle: 10% ethanol in 50 mM PBS containing 1% Tween 80

Study groups and reported outcomes
Group / dose	Comparator	Observed result	Reference
FK506 pretreatment 1 and 10 mg/kg (separate dose groups)	Matched FK506 vehicle; separate MK801 3 mg/kg and saline comparator groups	No significant reduction of quinolinate-, NMDA- or AMPA-associated lesion volumes at either FK506 dose	[3]

FK506 pretreatment: Model: Male Sprague Dawley rats; excitotoxic lesions in the stated brain regions; Reported limits: Group-specific sample sizes are not provided; Fig.1 caption gives 5–12 animals per group across experiments.

Methods and source locations

Compound reported in the paper: FK506 (tacrolimus); Compound label in the paper: FK506

Evidence concerns the named research compound in this model and source formulation; it does not validate an Adooq lot.

Methods: Materials, Excitotoxic lesions, Histopathological assessment; Results: Intraperitoneal drug administration; Fig.1 excitotoxic panels

Excitotoxic brain lesion volume: Blinded histopathology; unpaired t tests versus matched vehicle — Results: Intraperitoneal drug administration; Fig.1 five excitotoxic panels

Response of the positive-control comparator: Separate MK801 3 mg/kg arm; not a FK506 combination effect — Fig.1 caption and Results: Intraperitoneal drug administration

FK506 pretreatment · Materials; lesion-model and histopathology Methods; Results: Intraperitoneal drug administration; Fig.1

Specifications

Manufacturer	Adooq Bioscience
Actions	Inhibitor
CAS Number	104987-11-3
Applications	Calcineurin inhibitor (FKBP12 ligand)
Formula	C₄₄H₆₉NO₁₂
Molecular Weight	804
Synonyms	Fujimycin; Prograf; Tacrolimus
SMILES	C[C@@H]1C[C@@H]([C@@H]2[C@H](C[C@H]([C@@](O2)(C(=O)C(=O)N3CCCC[C@H]3C(=O)O[C@@H]([C@@H]([C@H](CC(=O)[C@@H](/C=C(/C1)\C)CC=C)O)C)/C(=C/[C@@H]4CC[C@H]([C@@H](C4)OC)O)/C)O)C)OC)OC

Storage & Solubility

In Vitro Solubility

Reported Solubility

Solvent	Reported Solubility
DMSO	81 mg/mL (100.74 mM)
Water	Insoluble
Ethanol	71 mg/mL (88.31 mM)

Preparing Stock Solutions

Stock preparation is unavailable for this product molecular weight.

Calculated stock concentrations do not establish solvent solubility. Refer to the reported solubility data for experimental guidance.

In Vivo Preparation

Concentration: 14 mg/mL
Vehicle: 5% DMSO+corn oil

Storage

Store powder at -20°C, keep desiccated.
In powder form, the chemical is stable for 36 months.
In solution, store at -20°C and use within 1 month to prevent loss of potency. Aliquot to avoid multiple freeze/thaw cycles.

Research References

[1] Fruman DA, Klee CB, Bierer BE, et al. Calcineurin phosphatase activity in T lymphocytes is inhibited by FK 506 and cyclosporin A Proceedings of the National Academy of Sciences of the United States of America (1992). PMID: 1373887 DOI: 10.1073/pnas.89.9.3686 Source material
[2] Klettner A, Herdegen T. The immunophilin-ligands FK506 and V-10,367 mediate neuroprotection by the heat shock response British journal of pharmacology (2003). PMID: 12642403 DOI: 10.1038/sj.bjp.0705132 Source material
[3] Butcher SP, Henshall DC, Teramura Y, et al. Neuroprotective actions of FK506 in experimental stroke: in vivo evidence against an antiexcitotoxic mechanism The Journal of neuroscience : the official journal of the Society for Neuroscience (1997). PMID: 9278529 DOI: 10.1523/jneurosci.17-18-06939.1997 Source material

Publications

3 publications citing this product

Tomoya Terashima, .et al. , Regenerative Cellular Therapies for Neurological Diseases, 2025, August: 95-107
Ogawa Y, .et al. , Neurobiol Dis, 2018, Oct;118:142-154 PMID: 30026035
Yuko Okamoto, .et al. , J Drug Deliv Sci Technol, 2018, 47: 62-66

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FK-506 (Tacrolimus)

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Biological Activity

Bioactivity / Mechanism

Target & Activity

Cellular Effect

In Vitro Studies

Cellular calcineurin inhibition and rapamycin antagonism

Literature-Reported Treatment Conditions

Comparison of calcineurin and IL-2 inhibitory concentrations

Literature-Reported Treatment Conditions

Cell-type dependence of protection against oxidative injury

Literature-Reported Treatment Conditions

In Vivo Studies

FK506 pretreatment in focal cerebral ischemia

Conditions shared by the study groups

Failure to reduce excitotoxic lesions

Conditions shared by the study groups

Specifications

Storage & Solubility

In Vitro Solubility

Reported Solubility

Preparing Stock Solutions

In Vivo Preparation

Storage

Research References

Publications

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