Quinestrol

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Cat Number

API0232120

CAS Number

152-43-2

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Product Detail Description Customer Q&A

CAS Number

152-43-2

EINECS

205-803-1

Storage

Store at room temperature

Synonyms

Estrovis; Estrovister; Plestrovis; Eston; Estradiol-17-beta 3-cyclopentyl ether; Quinestrolum

Molecular Formula

C25H32O2

Molecular Weight

364.5

Smiles

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

Appearance

White to off-white powder

Melting Point

107-108°C

Boiling Point

502.5±50.0°C at 760 mmHg

Relative Density

1.2±0.1

General Description

Quinestrol is a synthetic, long-acting estrogenic steroid, specifically the 3-cyclopentyl ether of ethinylestradiol. The molecule contains a cyclopentyl group attached via an oxygen at the 3-position, which confers high lipophilicity and allows storage in adipose tissue. It is a prodrug that undergoes slow hepatic release and conversion to ethinylestradiol. The chemical structure is unique among estrogens due to the ether linkage protecting the phenolic hydroxyl group.

Mechanism of Action

Quinestrol itself has low estrogen receptor affinity. It is hydrolyzed in the liver and fat to release ethinylestradiol, which then binds to nuclear estrogen receptors (ERα and ERβ). The receptor complex regulates gene transcription, affecting reproductive physiology, including suppression of gonadotropin secretion, endometrial proliferation, and calcium metabolism. The sustained release from fat depots prolongs the duration of action to 7-14 days after a single dose.

Application

Quinestrol was used as a component of oral contraceptives (usually combined with a progestin) and for estrogen replacement therapy in postmenopausal women. It was also employed for the treatment of breast cancer and prostate cancer.

Does Quinestrol require protection from light during long-term storage?

Yes, it is photosensitive. Light exposure can cause photodegradation and isomerization of the cyclopentane ring. Store in light-resistant containers, preferably amber glass.

What is the recommended storage temperature for Quinestrol?

Store at controlled room temperature (15-25°C). Avoid excessive heat above 30°C, which can accelerate hydrolysis of the 3-cyclopentyl ether group.

Is Quinestrol stable in oral tablet formulations with standard excipients?

Yes, when formulated with moisture-protective packaging.

How is the impurity ethinyl estradiol (de-cyclopentylated quinestrol) monitored?

This primary hydrolysis product is specifically quantified using a stability-indicating HPLC method, ensuring it remains below USP limits.