Other Biologically Important Amines

Many drugs and other biologically important amines are commonly stored and used as their salts. Amine salts are less prone to decomposition by oxidation and other reactions, and they have virtually no fishy odor. The salts are soluble in water, and they are easily converted to solutions for syrups and injectables. 

To make use of the Mannich reaction it is possible to methylate the N-atom of the new side chain and eliminate trimethylamine. The product, a 3-methyleneindoleninium salt, can then be trapped with suitable nucleophiles. In the example shown in Scheme 7.7b, cyanide ion is used, and reduction of the resultant nitrile yields the important amine trypta-mine. Indol-3-ylacetonitrile is also the source of indol-3-ylacetic acid and other biologically useful compounds (see Section 7.1.7). 

As stated at the outset of this chapter, the primary fate of amino acids is their incorporation into protein. However, amino acids also serve as precursors for a number of other important molecules. These include processes leading to the formation of the porphyrin nucleus found in many oxygen-and electron-carrying proteins, of biologically active amines, and of glutathione. These two topics are examined below. 

Melatonin oxidation seems quite important for the production of other biologically active metabolites such as AFMK and A -acetyl-S-methoxykynur-amine (AMK). AMK interacts with reactive oxygen and nitrogen species, conveys protection to mitochondria, inhibits and downregulates COX-2. Thus, melatonin may be considered as a prodrug [61]. 

Allied with the chromatography of imidazoles have been methods of estimation of the compounds, particularly those of biological importance, either on the chromatograms or after elution. Most workers have used diazotized aromatic amines as colorimetric reagents,53,277-285 particularly nonsulfonated diazotized aniline derivatives.281-285 Mosebach et aZ.286 initially hydrolyzed. -substituted imidazoles with 10 A hydrochloric acid before separating the compounds by ion-exchange and paper chromatographic techniques prior to estimation. A number of other methods exist for the colori-... 

A wide variety of purines of synthetic and, particularly, biological importance such as kinetin [7V -(2-furfuryl)adenine], (E)- and (Z)-zeatin, A7 -benzyladenine, the base of puromycin, and other similarly substituted adenines have been synthesized by amination of halo- or methylsul-fanylpurines. Naturally occurring adenine (1) can be prepared byconversion of 6-chloropurine with butanol saturated with ammonia in a sealed tube. ... 

Optically active cyanohydrins are synthetic precursors of a-hydroxy carboxylic acids, a-amino carboxylic acids, /1-hydroxy amines, and several other classes of organic compound of biological importance [146]. Several efficient catalysts have been developed by using titanium as the central metal. 

---