Hormone synthetic substitutes

De Lange WE, Doorenbos H (1968) Hormones and synthetic substitutes. In Meyler L, Herxheimer A (eds) Side effects of drugs. Excerpta Medica, Amsterdam London New York, pp 383-421... 

Levothyroxine is used to treat hypothyroidism (an underactive thyroid gland). Thyroid hormone can be made from beef and pork thyroid, but this lacks standardization and it is difficult to control dosage. The synthetic drug is more desirable. Levothyroxine is one of two important thyroid hormones. It is converted into the second important hormone, liothyronine, in the body. The key step in the synthesis of structures such as levothyroxine is the substitution of an iodonium salt by an iodinated phenol. Siql-like reactions on an aromatic ring are not common, but an iodonium salt provides a good leaving group. 

Synthetic steroid hormones retain the common steroid nucleus, but they may contain novel substituents that affect their pharmacological activity. The two most widely used synthetic steroid estrogens are ethinyl estradiol (Estinyl) and mestranol, found in oral contraceptives. Synthetic steroids containing an ethinyl substitution are metabolized more slowly. Thus, these synthetic steroid hormones have better oral absorption properties and extended biological half-lives than the natural estrogens. 

Another variant on hormone replacement therapy involves using aU three types of sex steroid in parallel, starting from the argument that during the fertile period all three are sjmthesized by the ovary (7). A natural version of this therapy uses estradiol, testosterone (with or without dehydroepiandrosterone), and progesterone in an appropriate pharmaceutical form (for example micro-nized), so that absorption is attained without the need for 17-substitution. This approach naturally avoids some of the undesirable effects of the synthetic steroids, and has been stated to improve menopausal depression and anxiety. However, the adverse effects of all three types of component can be experienced. 

The work of many investigators soon showed it to be extremely widespread in plants, and it became clear that it was a fundamental plant hormone (e.g., reviews 530, 655a). Excessive production of indoleacetic acid by parasites is responsible for certain types of plant tumor (e.g., 948). The synthetic plant growth regulators, which are in general substituted phenoxyacetic acids, probably function as indoleacetic acid analogues. 

Franke, A., Mattern, G.. and Traber, W., Synthetical juvenile hormone. Part 4. pfiira-Substituted 2-methyl-5-phenyl-penten(l)-carboxylic acid derivatives, Helv. Chim. Acta, 58, 293, 1975. 

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