Designer substances

Learn how to design substances with predictabie properties, to streamiine the search for new and useful substances. 

Nomenclature. The terms active agent and pharmacon designate substances that are capable of modifying life processes irrespective of whether the effects elicited may benefit or harm the organisms concerned. By this definition, a toxin is also a pharmacon. Taken in a narrower sense, a pharmacon means a substance that is used for therapeutic purposes. An unequivocal term for such a substance is medicinal drug. 

When designing substances that contain oleftnic or acetylenic moieties, chemists should keep in mind the potential for these substituents to be bioactivated to electrophilic species and, whenever possible, incorporate other structural changes that lessen the likelihood for bioactivation. Terminal carbon-carbon double or triple bonds should be avoided or at least contain an alkyl substituent on the C-2 carbon (in the case of olefins) and alkyl substituents on the allylic or propargylic carbons. Halogens on terminal unsaturated carbons should be avoided. Aromatic substituents at the allylic or propargylic positions should also be avoided if allylic or propargylic hydrogens are present. 

Organonitriles are organic substances that contain the cyano (-C = N) group. Nitriles have wide commercial applications that include solvents, synthetic intermediates, pharmaceuticals, and monomers, to name just a few. As a class of substances, there are two types of toxicity associated with exposure to nitriles acute lethality and osteolathyrism. Some nitriles are known to cause both. The mechanisms by which nitriles cause these toxic effects, the corresponding relationships between nitrile structure and toxic potency for each effect, and the use of this information as a basis to design substances that may need to contain the functionality of the cyano group but will cause minimal toxicity have been discussed in detail [7]. Only the biochemical mechanism and SARs related to acute lethality of nitriles are discussed here. More detailed discussions are available [7, 8, 61]. 

ISOTOPE. An isotope is one of nvo or more nuclides ibal have the same number of protons in iheir nuclei. An> two isotopes have ihe same aiuniic number. However. their mass numbers, A. differ. Isotope is a term that stems from the Greek words, isos tsume) and topos (place , to designate substances having different atomic weights and vei having chemical properties so much alike I hat in the early days ol research ii was nor possible to perform ti chemical separation ol the isotope of a given element. 

From the corms of Gloriosa superba, Santavy and co-workers (310a) isolated a material, m.p. 158-161°, [a] —162° (chloroform), which was designated Substance Gj. A basic alkaloid, m.p. 229-231°, designated Substance Gg, was isolated from the same source. Substance Hg, m.p. 183-185°, was reported in one paper (294) to be a constituent of the corms of C. avtumnale. No analytical data were presented, but evidence for a tropoloid ring was obtained. 

The flowers of C. autumnale afforded trace quantities of a basic, glycosidio material, C27H33NO11, m.p. 310-314°, which was designated Substance M (303). The material contains three methoxyl groups and one acetyl function. Acetylation afforded a pentaacetate, m.p. 302-304°, [o]o —244° (chloroform). Preliminary tests indicated the absence of a tropolone ring. 

From the above it will be apparent that the physico-chemical properties of a potential agent must be very finely adjusted if it is to avoid the many casualties of storage, excretion, and degradation. In many cases, by accident or by design, substances have been obtained with properties favourable for their accumulation near an appropriate receptor then, if their chemical structure is complementary to that of the receptor, the desired biological action takes place. 

Over twenty-five years ago, Karlson and Butenandt (1) and Karlson and Luscher (121) proposed the term pheromone - from the Greek pherein (to carry) and hormon (to stimulate).- to designate substances which are secreted by an animal to the outside and then cause a specific reaction in an individual of the same species, such as the release of certain behavior or the induction of certain physiological responses. 

The primary surfactant ingredient (and possibly coproducts) must appear on the regional chemical inventories of approved chemicals such as TSCA in the United States, Canadian Designated Substance List (DSL) or Canadian Non-Designated Substance List (NDSL), and EINECS in Europe. 

The term folio acid is often, but not exclusively, used as a synonym for pteroyl-glutamio acid it is also employed to designate substances which are analogous biologically and not defined chemically. 

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