High Quality Estrogen Raw Steroids Powder Melengestrol Acetate for Anti Cancer CAS 2919-66-6
CAS No.: 2919-66-6
Suitable for: Adult
HS Code: 3001200020
Certification: ISO 9001, USP, GMP
Appearance: Light Yellow Crystalline Powder
Usage: Female hormone
Density: 1.15 g/cm3
Melting Point: 202-204 ° C(lit. )
Boiling Point: 516.1 ° C at 760 mmHg
Flash Point: 221.7 ° C
Melengestrol acetate (INN, USAN), sometimes abbreviated as MGA, is a steroidal progestin and antineoplastic agent.It is not approved for use in humans, and is instead used as a feed additive to promote growth in cattle, a purpose it is licensed for in the United States and Canada.It is an acetate ester of melengestrol, which in contrast, is not used in either animals or humans.
Melengestrol acetat is widely used as a growth promoting feed additive in cattle breeding in the USA and several other non-European countries. To explore the physiological effects of MGA four heifers were fed during 8 weeks with 0.5 mg MGA daily as registered in the USA and two heifers each received 0, 1.5 or 5 mg/day, respectively. Plasma samples were collected twice a week and concentrations of MGA, progesterone and estradiol-17beta were quantified. The pulsatile secretion of luteinizing hormone was investigated in 6-hour profiles before and during treatment. After slaughter the reproductive organs were examined and oestrogen residues in edible tissues were measured.
Four days after the beginning of MGA feeding MGA concentrations in plasma reached levels of 30 and 100-400 pg/mL depending on the dose received. Three weeks after the beginning of MGA feeding P4 plasma concentrations had dropped to base levels below 0.3 ng/mL in all three treatment groups. Mean plasma E2-17beta levels increased in physiological range from 1 to 5 pg/mL during 0.5 mg MGA/day feeding with many acyclic peaks. Overdosed MGA decreased E2 levels and suppressed cyclic peaks. Number and size of ovarian follicles were not altered by any treatment. Mean LH levels and pulse frequencies increased significantly during labelled treatment , while higher doses had reducing effects. The development of corpus luteum was suppressed. E2-17beta residues in fat increased about 300% following labelled MGA treatment.
To investigate the relation of ovarian morphology to increased body weight gain during administration of melengestrol acetate, ovaries of 100 Holstein dairy heifers were examined for characteristics of follicular maturation, signs of lipid secretion, and the presence of steroid-producing-type cell organelles. The heifers were fed either a normal or a high-protein level ration with or without 0.30-0.45 mg daily of MGA from 2.5 months of age to the age of first estrus or to breeding age. The high-level ration effect was not consistently mediated by the special development of ovarian structures.
MGA effect, like the weight-gain effect, was consistently evident after the time of first estrus. MGA suppressed estrus and ovulation, and resulted in the presence in the ovary, after regression of corpora lutea, of an increased number of large follicles. The largest follicles corresponding in structure to developing proestrous, mature estrous, or early atretic follicles contained hypertrophied theca interna cells showing lipid secretion signs and ultrastructural characteristics of steroid synthesis. The majority of the largest follicles, however, were atretic or late atretic and did not contain steroid-type cells. The development of replacement follicles was evident in ovaries with late atretic largest follicles. The weight-gain effect of MGA may therefore be associated with a steroidogenic, probably estrogenic, effect in the cow.
The use of steroid hormone analogues in animals used for human consumption has been a
source of international debate for many years. In the European Union, a total ban of anabolic agents
for growth promotion in food animals has been in place since 1988 on the bases of unknown or poorly
demonstrated food safety (Stephany 2001). After a review of 17 scientific studies by the Scientific
Committee on Veterinary Measures Relating to Public Health, the European Commission concluded that
hormonally-treated meat poses a risk to consumers (SCVPH 2002). Conversely, in Canada and the USA,
certain synthetic and natural anabolic steroid hormones are approved for use under controlled
regulations (Stephany 2001). Interestingly, after a review of the same 17 studies, Health Canada
concluded that residues in beef pose no undue risk to human health, provided the drugs are used and
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