Nature-Throid

Brand Name(s) Armour Thyroid, Nature-Throid NT, Westhroid Chemical Class ENDO-thyroid hormone in natural state... 

Many pesticides are not as novel as they may seem. Some, such as the pyre-throid and neonicotinoid insecticides, are modeled on natural insecticides. Synthetic pyrethroids are related to the natural pyrethrins (see Chapter 12), whereas the neo-nicotinoids share structural features with nicotine. In both cases, the synthetic compounds have the same mode of action as the natural products they resemble. Also, the synthetic pyrethroids are subject to similar mechanisms of metabolic detoxication as natural pyrethrins (Chapter 12). More widely, many detoxication mechanisms are relatively nonspecific, operating against a wide range of compounds that... 

Pyrethrins are naturally occurring pesticides derived from chrysanthemum plants. They are active against many insects and mites. Over-the-counter liquid and gel preparations of pyrethrins with piperonyl butoxide are available for the treatment of pediculosis (piperonyl butoxide inhibits the hydrolytic enzymes that metabolize the pyrethrins in the arthropod). A synthetic pyre-throid, permethrin (Elimite), is available by prescription. A lower concentration of permethrin (Nix) is available without prescription. Pyrethrins and permethrin are quite safe. 

Figure 6.2 Toxicity of halocyclopropane analogues of DDT. LD50 values for DDT and DCC as functions of the temperature. Note that DDT and its analogues and pyre-throids do not depend on chemical reactivity to be toxic. They can therefore be quite stable, as is the case with DDT. (Data from Holan, G. 1969. Nature, 221, 1025-1029.)...

The potentials of this and other similar chiral Schiff base complexes of copper were originally explored for the manufacture of synthetic pyre-throids, a class of highly active pesticides. Cyclopropane rings with asymmetric centers are an integral part of the molecular structures of synthetic pyrethroids. Synthetic pyrethroids were made because the natural product chrysanthemic acid, 7.69, and its derivatives have insecticidal properties. 

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