Quinestrol's primary target is the estrogen receptor (ER). As an estrogen receptor agonist, it diffuses into target cells and interacts with the estrogen receptor, leading to the activation of estrogen-responsive genes. This results in the typical effects of estrogens, including the development and maintenance of female secondary sexual characteristics, regulation of the menstrual cycle, and effects on bone and lipid metabolism.

In vitro, Quinestrol acts as an estrogen receptor agonist. It binds to and activates the estrogen receptor, leading to the transcription of estrogen-responsive genes. Its activity can be assessed in cell-based reporter assays using estrogen-responsive element (ERE)-driven luciferase reporters.

In vivo, Quinestrol is used in hormone replacement therapy for treating symptoms of menopause such as hot flashes. It has also been used occasionally to treat breast cancer and prostate cancer. Due to its storage in adipose tissue and slow release, it provides a prolonged estrogenic effect, allowing for less frequent dosing compared to other estrogens.

The in vitro activity of Quinestrol is typically assessed using estrogen receptor binding assays and cell-based reporter assays. In receptor binding assays, the estrogen receptor is incubated with a radiolabeled estrogen (e.g., [3H]estradiol) in the presence of varying concentrations of Quinestrol. The displacement of the radiolabeled ligand is measured to determine the binding affinity (Ki). In cell-based reporter assays, cells (e.g., MCF-7 breast cancer cells) are transfected with a plasmid containing an estrogen-responsive element (ERE) driving a luciferase reporter gene. Cells are treated with Quinestrol, and luciferase activity is measured to quantify the transcriptional activation.

For cellular assays, estrogen receptor-positive cell lines such as MCF-7 or T47D breast cancer cells are used. Cells are cultured in estrogen-depleted media (e.g., phenol red-free media with charcoal-stripped serum) and treated with various concentrations of Quinestrol (typically ranging from 0.1 nM to 10 µM) for different time periods (e.g., 24-72 hours). Cell proliferation is assessed using the MTT assay or by counting cell numbers. The expression of estrogen-responsive genes (e.g., pS2, progesterone receptor) is analyzed by quantitative real-time PCR or Western blotting.

In vivo, Quinestrol is typically administered orally. Its effects on the reproductive system and bone metabolism can be assessed in ovariectomized (OVX) rats, a model for postmenopausal estrogen deficiency. The compound is administered at various doses (e.g., 0.01-1 mg/kg) daily or weekly. Endpoints include uterine weight (as a measure of estrogenic activity), bone mineral density, and serum levels of hormones and bone turnover markers.

Absorption, Distribution and Excretion
Absorbed after oral administration. Metabolism/Metabolites Primarily metabolized to the parent compound ethinylestradiol. Ethinylestradiol is metabolized in the liver. Quantitative analysis shows that the main metabolic pathway of ethinylestradiol in rats and humans is aromatic hydroxylation, which is the same as the metabolic pathway of natural estrogens.
Quinestrol is orally bioavailable and is stored in adipose tissue, from which it is slowly released, providing a prolonged duration of action. It is a prodrug that is metabolized to ethinylestradiol, its active metabolite. The long half-life allows for less frequent dosing, such as once weekly or even less frequently, in clinical use.

As an estrogen, Quinestrol shares the toxicity profile of other estrogens. Side effects may include nausea, breast tenderness, fluid retention, and an increased risk of thromboembolic events (e.g., deep vein thrombosis, pulmonary embolism). Long-term use of estrogens has been associated with an increased risk of endometrial cancer (when used without a progestin) and breast cancer. It is contraindicated in pregnancy and in individuals with a history of estrogen-dependent tumors or thromboembolic disorders.

Li J, Chen F, Chen Y, Wang Z. Mitochondrial- and Fas-L-mediated pathways involved in quinestrol induced spermatogenic apoptosis in adult rat testes. Toxicol Mech Methods. 2014 Dec;24(9):609-15. doi: 10.3109/15376516.2014.970680. Epub 2014 Oct 10. Review. PubMed PMID: 25258304.

Quinestrol is a 17-hydroxysteroid and a terminal alkyne compound. It is an isoestrone functionally related to 17β-estradiol. It is the 3-cyclopentyl ether of ethinylestradiol. Quinestrol is only found in individuals who have used or taken this drug. Estrogen diffuses to target cells and interacts with protein receptors (estrogen receptors). Estrogen interacts with target cell receptors. When an estrogen receptor binds to its ligand, it can enter the nucleus of the target cell and regulate gene transcription, leading to the formation of messenger RNA (mRNA). mRNA interacts with ribosomes to produce specific proteins that express the effects of estradiol on target cells. Estrogen can increase the synthesis of sex hormone-binding globulin (SHBG), thyroid-binding globulin (TBG), and other serum proteins in the liver and inhibit the secretion of follicle-stimulating hormone (FSH) from the anterior pituitary gland. Target cells include the female reproductive tract, mammary glands, hypothalamus, and pituitary gland. Estrogen increases the synthesis of sex hormone-binding globulin (SHBG), thyroid-binding globulin (TBG), and other serum proteins in the liver, and inhibits the secretion of follicle-stimulating hormone (FSH) from the anterior pituitary gland. The combined use of estrogen and progesterone can suppress the hypothalamic-pituitary system, reducing the secretion of gonadotropin-releasing hormone (GnRH).
Ethinyl estradiol 3-cyclopentyl ether. After absorption from the gastrointestinal tract, this drug is stored in adipose tissue, released slowly, and primarily metabolized to its parent compound. It was previously used in estrogen replacement therapy. (From JAMA Drug Evaluation Annals, 1992, p. 1011)
Drug Indications

Used in hormone replacement therapy to treat menopausal symptoms, such as hot flashes. Also used to treat breast and prostate cancer.
Mechanism of Action

Estrogen diffuses to target cells and interacts with protein receptors (estrogen receptors). After binding to receptors on target cells, estrogen enters the target cell nucleus, regulating gene transcription and forming messenger RNA (mRNA). mRNA interacts with ribosomes to produce specific proteins that express the effects of estradiol on target cells. Estrogen increases the synthesis of sex hormone-binding globulin (SHBG), thyroid-binding globulin (TBG), and other serum proteins in the liver, and inhibits the secretion of follicle-stimulating hormone (FSH) from the anterior pituitary gland. Its target cells include the female reproductive tract, mammary glands, hypothalamus, and pituitary gland. The combined use of estrogen and progesterone can suppress the hypothalamic-pituitary system, reducing the secretion of gonadotropin-releasing hormone (GnRH).
Quinestrol is a synthetic estrogen that was used in hormone replacement therapy and for the treatment of certain cancers. Its development as a long-acting estrogen was based on the concept of storing the compound in adipose tissue for slow release. It is known by various brand names, including Estrovis. Its use has declined with the development of other estrogens and a better understanding of the risks associated with hormone replacement therapy.

C25H32O2

364.5204

364.24

152-43-2

9046

White to off-white solid powder

1.2±0.1 g/cm3

502.5±50.0 °C at 760 mmHg

107 - 108ºC

218.8±24.4 °C

0.0±1.4 mmHg at 25°C

1.596

6.67

1

2

3

27

613

5

C[C@]12CC[C@H]3[C@H]([C@@H]1CC[C@]2(C#C)O)CCC4=C3C=CC(=C4)OC5CCCC5

PWZUUYSISTUNDW-UHFFFAOYSA-N

InChI=1S/C25H32O2/c1-3-25(26)15-13-23-22-10-8-17-16-19(27-18-6-4-5-7-18)9-11-20(17)21(22)12-14-24(23,25)2/h1,9,11,16,18,21-23,26H,4-8,10,12-15H2,2H3

(8R,9S,13S,14S,17R)-3-cyclopentyloxy-17-ethynyl-13-methyl-7,8,9,11,12,14,15,16-octahydro-6H-cyclopenta[a]phenanthren-17-ol

W-3566W 3566W3566Estrovis Quinestrolum Estrovister Plestrovis Eston Ethinyl Estradiol 3 Cyclopentyl Ether Ethinyl Estradiol 3-Cyclopentyl Ether

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 : ~250 mg/mL (~685.83 mM)

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*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.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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