- `Equilin (7-Dehydroestrone)` exhibits estrogenic activity, presumably targeting estrogen receptors (ERs) [1]
- `Equilin (7-Dehydroestrone)` activates NMDA receptors to promote cortical neuron growth, with an EC50 of ~10 nM for neuron survival promotion [2]
- `Equilin (7-Dehydroestrone)` activates the NF-κB signaling pathway to increase monocyte-endothelial adhesion, with an EC50 of ~25 nM for NF-κB p65 nuclear translocation [3]

Equilin in conjugated equine estrogen promotes monocyte-endothelial adhesion via NF-κB signaling[3].

---

- In primary rat cortical neuron cultures, treatment with `Equilin (7-Dehydroestrone)` (1 nM-1 μM) for 72 hours increased neuron viability dose-dependently: 10 nM increased viability by 35%, 100 nM by 62%, and 1 μM by 78% (MTT assay). This effect was completely blocked by MK-801 (1 μM, an NMDA receptor antagonist) [2]
- In human umbilical vein endothelial cells (HUVECs) co-cultured with THP-1 monocytes, `Equilin (7-Dehydroestrone)` (1 nM-100 nM) for 24 hours increased monocyte-endothelial adhesion rate: 10 nM increased adhesion by 41%, 100 nM by 73% (flow cytometry). Western blot showed 100 nM `Equilin` upregulated NF-κB p65 (2.1-fold) and ICAM-1 (3.4-fold) protein expression [3]

- In ovariectomized female rats (n=5 per group), subcutaneous injection of `Equilin (7-Dehydroestrone)` (0.1 mg/kg/day or 0.5 mg/kg/day) for 14 days increased uterine weight by 52% (0.1 mg/kg) and 98% (0.5 mg/kg) compared to the vehicle group [1]
- In adult male mice (n=6 per group), intraperitoneal injection of `Equilin (7-Dehydroestrone)` (1 mg/kg) for 3 days increased liver glycogen content by 38% vs. vehicle [1]
- In ovariectomized female rats with cortical neuron injury (n=6 per group), oral gavage of `Equilin (7-Dehydroestrone)` (0.3 mg/kg/day) for 21 days increased surviving cortical neurons by 45% vs. vehicle; this effect was abolished by co-administration of MK-801 (0.1 mg/kg/day) [2]

- NMDA receptor activity assay (to verify `Equilin (7-Dehydroestrone)` targeting): Primary rat cortical neurons were seeded in 24-well plates (1×10⁵ cells/well) and treated with `Equilin` (10 nM) ± MK-801 (1 μM) for 48 hours. Intracellular Ca²⁺ concentration was measured using a Ca²⁺-sensitive fluorescent dye (excitation at 488 nm, emission at 525 nm). `Equilin` increased Ca²⁺ influx by 65% vs. control, while MK-801 reduced this increase by 92% [2]
- NF-κB p65 nuclear translocation assay: HUVECs were treated with `Equilin (7-Dehydroestrone)` (100 nM) for 1 hour, then nuclear and cytoplasmic proteins were extracted. NF-κB p65 protein in the nuclear fraction was quantified by ELISA (detection at 450 nm), and `Equilin` increased nuclear p65 by 2.8-fold vs. control [3]

- Primary cortical neuron viability assay: Cortical tissues were isolated from embryonic day 18 rat brains, dissociated into single cells, and seeded in 96-well plates (5×10³ cells/well) in neurobasal medium. `Equilin (7-Dehydroestrone)` (0.1 nM-1 μM) was added, and cells were cultured for 72 hours. MTT solution (5 mg/mL) was added, incubated for 4 hours, DMSO was added to dissolve formazan, and absorbance was measured at 570 nm [2]
- Monocyte-endothelial adhesion assay: HUVECs were seeded in 6-well plates (2×10⁵ cells/well) and treated with `Equilin (7-Dehydroestrone)` (1-100 nM) for 24 hours. THP-1 monocytes (labeled with fluorescent dye) were added at a 5:1 ratio (monocytes:HUVECs) and incubated for 1 hour. Non-adherent monocytes were washed away, and adherent cells were counted under a fluorescence microscope [3]

- Ovariectomized rat uterine weight assay: Female Sprague-Dawley rats (200-250 g) were ovariectomized under anesthesia. After 7 days of recovery, rats were divided into 3 groups (n=5): vehicle (0.1% ethanol + 0.9% saline), `Equilin (7-Dehydroestrone)` 0.1 mg/kg, and 0.5 mg/kg. `Equilin` was administered via subcutaneous injection once daily for 14 days. Rats were euthanized, uteri were excised and weighed [1]
- Mouse liver glycogen assay: Male ICR mice (25-30 g) were divided into 2 groups (n=6): vehicle (0.1% ethanol + PBS) and `Equilin (7-Dehydroestrone)` 1 mg/kg. `Equilin` was administered via intraperitoneal injection once daily for 3 days. Livers were homogenized, and glycogen content was measured using a colorimetric assay kit [1]
- Ovariectomized rat cortical neuron protection assay: Ovariectomized female rats (220-260 g) were given cortical injury via needle stab. Rats were divided into 3 groups (n=6): vehicle (0.5% carboxymethyl cellulose), `Equilin` 0.3 mg/kg, and `Equilin` 0.3 mg/kg + MK-801 0.1 mg/kg. Drugs were administered via oral gavage once daily for 21 days. Brains were sectioned, and surviving neurons were counted via Nissl staining [2]

Absorption, Distribution and Excretion
Absorbed well. Metabolism/Metabolites Liver.

Toxicity Summary
Estrogens enter cells of reactive tissues (e.g., female organs, breasts, hypothalamus, pituitary gland), where they interact with protein receptors, subsequently increasing the rate of DNA, RNA, and certain protein synthesis. Estrogens can reduce the secretion of hypothalamic gonadotropin-releasing hormone, thereby reducing the secretion of pituitary follicle-stimulating hormone (FSH) and luteinizing hormone (LH). Protein Binding 90% bound to plasma proteins. In rats, subcutaneous injection of Equilin (7-dehydroestradiol) (up to 0.5 mg/kg/day for 14 days) caused uterine hyperplasia (physiological estrogen effect) [1]. In human umbilical vein endothelial cells (HUVECs), Equilin (7-dehydroestradiol) (up to 1 μM for 24 hours) maintained cell viability >90% (CCK-8 assay) [3].

[1]. Some biological properties of equilin. Biochem J. 1935;29(2):371-377.

[2]. Equilin, a principal component of the estrogen replacement therapy premarin, increases the growth of cortical neurons via an NMDA receptor-dependent mechanism. Exp Neurol. 1997;147(2):211-220.

[3]. Equilin in conjugated equine estrogen increases monocyte-endothelial adhesion via NF-κB signaling. PLoS One. 2019;14(1):e0211462. Published 2019 Jan 30.

Equilin is a 17-oxosteroid and 3-hydroxysteroid derived from the hydrogenation of estradiol. It is an estrogenic steroid produced by horses, with four double bonds on its A and B rings. High concentrations of Equilin are found in the urine of pregnant mares. Equilin is a naturally occurring, estrogenic steroid extracted from the urine of pregnant mares. It is an estrogenic steroid produced by horses, with four double bonds on its A and B rings. High concentrations of Equilin are found in the urine of pregnant mares. Equilin is one of the estrogen mixtures isolated from horse urine, marketed under the trade name Premarin. Premarin has become the most commonly used hormone replacement therapy estrogen in the United States. Estrone is the main estrogen in Premarin (approximately 50%), while equine ketone accounts for approximately 25%. Estrone is the main estrogen normally present in women. Equine ketone is not normally present in women, hence the interest in its effects on the human body. The estrogen in pregalilin exists primarily in a "conjugated" form, a modified chemical form in which the active estrogen is bound to other chemical groups such as sulfate. Estrone sulfate is usually the primary form of estrogen in women. Once in the female body, the conjugated estrogen in pregalilin is converted to active unconjugated estrogen or excreted. Estrone can be converted to estradiol, which is considered the primary active estrogen in women. Estradiol is an estrogenic steroid produced by equines. It has four double bonds in its A and B rings. High concentrations of estrogen are found in the urine of pregnant mares. Drug Indications Used to treat moderate to severe vasomotor symptoms associated with menopause, atrophic vaginitis, osteoporosis, hypogonadism, castration, primary ovarian failure, breast cancer (for palliative care only), and advanced androgen-dependent prostate cancer (for palliative care only). Mechanism of Action Estrogens enter cells of responding tissues (e.g., female organs, breasts, hypothalamus, pituitary gland), where they interact with protein receptors, subsequently increasing the rate of DNA, RNA, and certain protein synthesis. Estrogens can reduce the secretion of gonadotropin-releasing hormone from the hypothalamus, which in turn reduces the secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the pituitary gland. Pharmacodynamics Pregamarin is a component of pregamarin (a conjugated estrogen), a mixture of estrone, pregamarin, 17α-dihydropregamarin, and other sulfated water-soluble salts of related steroids, possibly derived from the urine of pregnant horses or yam and soybean plants. Estrogens play a crucial role in the development and maintenance of the female reproductive system and secondary sexual characteristics. They promote the growth and development of the vagina, uterus, and fallopian tubes, as well as breast enlargement. Estrogen indirectly participates in bone formation, the maintenance of tension and elasticity of the urogenital system, changes in the epiphyses of long bones (thus promoting the growth spurt and its termination during puberty), the growth of axillary and pubic hair, and pigmentation of the nipples and genitals. The decline in estrogen activity at the end of the menstrual cycle can trigger menstruation, although the cessation of progesterone secretion is the most important factor in a mature ovulatory cycle. However, estrogen is the main determinant of menstruation in pre-ovulatory or non-ovulatory cycles. Estrogen also affects the release of pituitary gonadotropins. The pharmacological effects of conjugated estrogens are similar to those of endogenous estrogens.

---

-7-dehydroestrone (Equilin) is a natural estrogen isolated from the urine of pregnant mares and is the main component of conjugated estrogens (CEE, such as Premarin) used in estrogen replacement therapy (ERT)[2][3].
- The mechanism by which 7-dehydroestradiol induces cortical neuronal growth involves the activation of NMDA receptors: it increases NMDA receptor-mediated Ca²⁺ influx, thereby activating downstream survival signaling pathways (e.g., PI3K/Akt) [2].
- 7-dehydroestradiol promotes monocyte-endothelial cell adhesion by activating NF-κB: it induces phosphorylation and nuclear translocation of NF-κB p65, thereby upregulating adhesion molecules (e.g., ICAM-1, VCAM-1) on endothelial cells [3].
- In ovariectomized rats, equine estrone (7-dehydroestradiol) has weaker estrogenic activity than estrone: 0.5 mg/kg equine estrone causes approximately 80% of the uterine weight increase caused by 0.5 mg/kg estrone [1].

C₁₈H₂₀O₂

268.35

268.146

474-86-2

Equilin-d4;285979-79-5

223368

White to off-white solid

1.2±0.1 g/cm3

459.1±45.0 °C at 760 mmHg

238-240ºC(lit.)

195.4±21.3 °C

0.0±1.2 mmHg at 25°C

1.626

3.53

1

2

0

20

466

3

OC1C=C2CC=C3[C@@]4([H])[C@@](C(CC4)=O)(CC[C@]3([H])C2=CC=1)C

WKRLQDKEXYKHJB-HFTRVMKXSA-N

InChI=1S/C18H20O2/c1-18-9-8-14-13-5-3-12(19)10-11(13)2-4-15(14)16(18)6-7-17(18)20/h3-5,10,14,16,19H,2,6-9H2,1H3/t14-,16+,18+/m1/s1

(9S,13S,14S)-3-hydroxy-13-methyl-9,11,12,14,15,16-hexahydro-6H-cyclopenta[a]phenanthren-17-one

7-Dehydroestrone; Equilin

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: ~100 mg/mL (~372.7 mM)

Solubility in Formulation 1: ≥ 2.5 mg/mL (9.32 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.

---

Solubility in Formulation 2: ≥ 2.5 mg/mL (9.32 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.

---

View More

Solubility in Formulation 3: ≥ 2.5 mg/mL (9.32 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.

---

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