A3AR; IB-MECA acts as an agonist at the A₃-adenosine receptor. Its affinity for the rat brain A₃-adenosine receptor is reported with a Kᵢ value of 1.1 nM [1].

In rat RBL-2H3 mast cells, IB-MECA stimulates phosphoinositide breakdown, measured by the accumulation of [³H]IP₁ and [³H]IP₂. The EC₅₀ for this effect on [³H]IP₁ accumulation is 8.5 ± 1.7 μM [1].
IB-MECA causes a concentration-dependent elevation of intracellular calcium levels ([Ca²⁺]ᵢ) in RBL-2H3 cells. This response is more potent than its effect on phosphoinositide breakdown, with an EC₅₀ of 0.11 ± 0.005 μM. It is one of the most potent compounds tested for this effect [1].
The efficacy of IB-MECA in elevating [Ca²⁺]ᵢ is relatively high, with a relative efficacy of 55% compared to NECA (set at 100%) [1].

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Piclidenoson can reduce the amount of cAMP stimulated by forskolin, with EC50 values in OVCAR-3 cells of 0.82 μM and in Caov-4 cells of 1.2 μM, respectively [2].
Piclidenoson (0.0001-100 μM; 48 hours) dramatically lowers human ovarian line cell viability in a dose-dependent manner; for OVCAR-3 and Caov-4 cells, the IC50s are 32.14 μM and 45.37 μM, respectively [2].
Piclidenoson (0.001-100 μM; 48 hours) through the caspase pathway.

Piclidenoson (105 μg/kg; IP) improvement γ The survival rate of irradiated mice [3].
• In male B10CBAF1 mice lethally irradiated with 8.5 Gy γ-rays, a single intraperitoneal dose of Piclidenoson (IB-MECA) (105 μg/kg) administered 0.5 h post-irradiation significantly increased the mean survival time (MST) of mice to 23.3 days (95% CI: 20.3; 26.3) compared with the control group (18.1 days, 95% CI: 15.1; 21.1), with a P value of 0.020 via log-rank test; the cumulative percentage 30-day survival (CPS) of mice treated with the drug alone was 56.0% (95% CI: 34.8; 72.7), which was higher than the control group (28.0%, 95% CI: 12.4; 46.0) but without statistical significance (P=0.084 via Fisher’s exact test) [3]

• Combined administration of Piclidenoson (IB-MECA) (105 μg/kg, i.p., 0.5 h post-irradiation) and meloxicam (20 mg/kg, i.p., 1 h post-irradiation) in 8.5 Gy γ-irradiated male B10CBAF1 mice resulted in the most significant increase in MST (24.9 days, 95% CI: 21.9; 27.8, P=0.003 vs control) and the only statistically significant elevation in CPS (68.0%, 95% CI: 46.1; 82.5, P=0.010 vs control) among all treatment groups [3]

• In sublethally γ-irradiated mice, Piclidenoson (IB-MECA) and meloxicam mutually potentiated their hematopoiesis-stimulating effects when administered in combination [3]

• Piclidenoson (IB-MECA) stimulates the proliferation of hematopoietic progenitor cells and the bone marrow granulocytic system, and acts as a homeostatic regulator of bone marrow hematopoiesis in irradiated mammalian organisms [3]

• Administration of Piclidenoson (IB-MECA) in 2–9 doses starting no earlier than 24 h after irradiation did not significantly influence the survival parameters of lethally irradiated mice [3]

• Piclidenoson (IB-MECA) can induce the production of granulocyte colony-stimulating factor (G-CSF), which contributes to damping radiation-induced cell apoptosis and mitigating radiation damage [3]

Phosphoinositide Breakdown Assay: RBL-2H3 cells were grown in Eagle's Minimum Essential Medium with 10% fetal bovine serum and antibiotics. Cells were plated in 12-well plates at a density of 5×10⁵ cells/well in the presence of myo-[³H]inositol (10 mCi/ml) and, in some experiments, with 0.5 μg/ml of DNP-specific IgE. The following day, cells were washed and incubated in a buffer containing 108 mM NaCl, 4.7 mM KCl, 10 mM LiCl, 1.2 mM MgSO₄, 1.2 mM KH₂PO₄, 0.5 mM EDTA, 10 mM glucose, 20 mM Hepes (pH 7.4), and 3 mM CaCl₂. Cells primed with IgE were preincubated with the antigen DNP-HSA (20 ng/ml) for 10 min. IB-MECA was then added and incubated for 1 or 15 minutes at 37°C. The reaction was stopped with 12% trichloroacetic acid. The supernatants were processed using anion exchange chromatography to elute [³H]inositol phosphates. Results were expressed as counts per minute of [³H]IP₁ per 10,000 cpm of [³H]inositol-labeled membrane lipids [1].
Intracellular Calcium Assay: RBL-2H3 cells were detached using trypsin and EDTA, then suspended in Hepes buffer (pH 7.4, containing 135 mM NaCl, 5 mM KCl, 1 mM CaCl₂, 1 mM MgCl₂, 5.6 mM glucose, 10 mM Hepes, and 0.1% bovine serum albumin) with 2.5 mM probenecid. Some cells were incubated overnight with 0.5 μg/ml DNP-specific IgE. Cells were loaded with 2 μM fura-2-acetoxymethyl ester at 37°C for 45 minutes. Fluorescence changes were measured in a spectrofluorimeter at 37°C with excitation at 340 and 380 nm and emission at 510 nm. [Ca²⁺]ᵢ was calculated from the fluorescence ratio. IB-MECA was added to the stirred cell suspension to assess its effect on calcium levels [1].

Cell Line: OVCAR-3 cells, Caov-4 cells
Concentration: 0.0001-100 μM
Incubation Time: 48 hours
Result: Resulted in a dose-dependent reduction in the cell viability.

B10CBAF1 male mice aged 3 months (average 30 g)
105 μg/kg
Intraperitoneal injection, 0.5 h after irradiation

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• Experimental animals: 3-month-old male B10CBAF1 mice with an average body weight of 30 g, raised under controlled conditions with ad libitum access to standardized pelleted diet and HCl-treated tap water; all animal procedures were in accordance with European Community Guidelines and approved by the Institute’s Ethical Committee [3]
• Irradiation procedure: Mice were subjected to total body γ-irradiation using a 60Co source at a dose rate of 0.5 Gy/min, with a lethal total dose of 8.5 Gy [3] • Drug preparation of Piclidenoson (IB-MECA): Initially dissolved in dimethyl sulfoxide (DMSO), then diluted with sterile saline to a final DMSO concentration of 2% [3]
• Administration of Piclidenoson (IB-MECA) alone: A single intraperitoneal (i.p.) dose of 105 μg/kg in a volume of 0.2 ml, administered 0.5 h after 8.5 Gy γ-irradiation; control mice for this group received an i.p. injection of the solvent containing 2% DMSO at the same time point [3]
• Combined administration of Piclidenoson (IB-MECA) and meloxicam: Piclidenoson (IB-MECA) was given as a single i.p. dose of 105 μg/kg (0.2 ml) 0.5 h post-irradiation, and meloxicam (dissolved in 0.9% sterile saline) was administered as a single i.p. dose of 20 mg/kg (0.2 ml) 1 h post-irradiation; the overall control group received two vehicle injections at the corresponding time intervals [3]
• Survival observation: The survival status of experimental mice was recorded daily up to 30 days after irradiation; the experiment was repeated 5 times with 5 animals in each group (25 animals per group in total) [3]
• Statistical analysis: Survival time was analyzed by Kaplan–Meier methodology, MST was derived from the Kaplan–Meier curve; differences in MST between groups were tested by log-rank test, and differences in CPS were tested by Fisher’s exact test, with a significance level set at P ≤ 0.05 [3]

[1]. Activation of Phosphoinositide Breakdown and Elevation of Intracellular Calcium in a Rat RBL-2H3 Mast Cell Line by Adenosine Analogs: Involvement of A(3)-Adenosine Receptors? Drug Dev Res. 1996 Sep 1;39(1):36-46.

[2]. Mitochondrial and caspase pathways are involved in the induction of apoptosis by IB-MECA in ovarian cancer cell lines. Tumour Biol. 2014 Nov;35(11):11027-11039.

[3]. Agonist of the adenosine A3 receptor, IB-MECA, and inhibitor of cyclooxygenase-2, meloxicam, given alone or in a combination early after total body irradiation enhance survival of γ-irradiated mice. Radiat Environ Biophys. 2014 Mar;53(1):211-215.

[4]. Potential Therapeutic Options for COVID-19: Current Status, Challenges, and Future Perspectives. Front Pharmacol. 2020; 11: 572870.

3-Iodobenzyl-5'-N-methylcarboxamide adenosine is a derivative of adenosine in which the 5'-hydroxymethyl group is replaced by an N-ethylcarboxamide group, and one hydrogen atom on the outer ring amino group is replaced by a 3-iodobenzyl group. It is an adenosine A3 receptor agonist. It belongs to the adenosine class of compounds and is an organic iodine compound and a monocarboxylic acid amide. Its function is related to adenosine. CF101 (generic name IB-MECA) is an anti-inflammatory drug used to treat rheumatoid arthritis. Its unique mechanism of action is antagonism of the adenosine A3 receptor. CF101 is an oral medication with a good safety profile. It is also considered for the treatment of other autoimmune inflammatory diseases such as Crohn's disease, psoriasis, and dry eye. Piklidinosin is an orally bioavailable adenosine A3 receptor (A3AR) agonist with potential anti-inflammatory activity. After administration, piklidinosin selectively targets, binds to, and activates A3AR expressed on the cell surface, thereby activating the signal transduction pathways in which A3AR plays a key role. This inhibits nuclear factor-κB (NF-κB) signaling and suppresses the production of inflammatory cytokines such as tumor necrosis factor (TNF) and various interleukins. A3AR is a G protein-coupled receptor that plays a key role in a variety of inflammatory diseases and certain types of cancer.

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Drug Indications
It has been investigated for the treatment of cancer/tumor (not specified), eye diseases/infections, psoriasis and psoriasis-related diseases, and rheumatoid arthritis. Can-Fite BioPharma reports that CF101, by targeting the adenosine A3 receptor, can also be used to treat Crohn's disease, a serious gastrointestinal disorder.

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Mechanism of Action
CF101 is an A3AR agonist. A3AR is highly expressed in inflammatory cells and overexpressed in peripheral blood mononuclear cells, reflecting its role in distal inflammatory processes. In normal tissues, the expression of the adenosine A3 receptor is low. Activation of A(3)AR with specific agonists can disrupt the NF-kappaB signaling pathway in inflammatory cells and initiate immunomodulatory effects.

C18H19IN6O4

510.28

510.051

C, 42.37; H, 3.75; I, 24.87; N, 16.47; O, 12.54

152918-18-8

152918-18-8

123683

White to off-white solid powder

2.0±0.1 g/cm3

1.808

2.08

4

8

5

29

589

4

IC1=C([H])C([H])=C([H])C(=C1[H])C([H])([H])N([H])C1=C2C(=NC([H])=N1)N(C([H])=N2)[C@@]1([H])[C@@]([H])([C@@]([H])([C@@]([H])(C(N([H])C([H])([H])[H])=O)O1)O[H])O[H]

HUJXGQILHAUCCV-MOROJQBDSA-N

InChI=1S/C18H19IN6O4/c1-20-17(28)14-12(26)13(27)18(29-14)25-8-24-11-15(22-7-23-16(11)25)21-6-9-3-2-4-10(19)5-9/h2-5,7-8,12-14,18,26-27H,6H2,1H3,(H,20,28)(H,21,22,23)/t12-,13+,14-,18+/m0/s1

(2S,3S,4R,5R)-3,4-dihydroxy-5-(6-(3-iodobenzylamino)-9H-purin-9-yl)-N-methyltetrahydrofuran-2-carboxamide

ALB-7208; ALB 7208; CF101; IB-MECA; CF-101; CF 101; ALB7208; IB MECA; Piclidenoson

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO: ≥ 45 mg/mL (~88.2 mM)

Solubility in Formulation 1: ≥ 2.5 mg/mL (4.90 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.5 mg/mL (4.90 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 2.5 mg/mL (4.90 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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 (Please use freshly prepared in vivo formulations for optimal results.)