Special Biological Activities

A pro-drug is a substance that has no special biological activity per se but can be converted into an active drug by enzymic action in the body. Thus, all the initial proteins formed by ribosomal synthesis that contain a peptide hormone structure locked within their amino-acid sequence are analogous to pro-drugs. The hormones are released by the action of proteolytic enzymes. Usually, however, the term prodrug is restricted to artificially synthesised molecules that are acted upon by the... 

The tertiary metabolites seem to be devoid of any special biological activity of their own. They may conceivably be rendered active by mutations affecting their precursors and in this way gain access to the main biochemical events. If this happens they must eventually be subjected to regulatory systems such as enzymatic intervention. Their introduction into metabolic processes and their new activity demands means of regulation other than purely kinetic and thermodynamic control. 

This chapter is focused on the biosynthesis and actions of lipoxins, resolvins, protectins, and maresins. Each group of PUFA-derived lipid mediators has its own distinct biosynthetic pathways and features a specialized biological activity profile. 

Five compounds (TABLE 5 FIGURE 4) exhibited lethality or sickness in at least one test at a test concentration one-tenth or less below that predicted by equations 2 or 3. Two of these (45,47) are thiocyanate derivatives, which as a class are known to possess special biological activity (Reid 1966 Wilcoxon and McCallen 1935). The thiocyanate functional group is also known to be a chemically reactive moiety (Reid 1966 Bacon 1961). Thiocyanates can react as electrophiles by nucleophilic attack at either the carbon or sulphur atom (SCHEME 1). In the latter case, cyanide would be released as a chemical leaving group. Hermans et al. (1985) has demonstrated that the acute fish lethality of various nonelectrolyte electrophilic compounds correlates poorly with log P (equation 8). 

Lee et al. also applied this methodology to the synfliesis of natural products mallotophilippen C 154 and E 160 this family of natural products was isolated from a deciduous tree Mallotus philippinensis. Mallotophilippens has shown special biologic activity, and potentially treats rheumatoid arthritis [81,82]. The total synthesis of mallotophilippen C 154 is shown in Scheme 12.37. Treatment of 2,4,6-trihydroxyace-tophenone 148 and geranyl bromide with anhydrous... 

One of the virtues of the Fischer indole synthesis is that it can frequently be used to prepare indoles having functionalized substituents. This versatility extends beyond the range of very stable substituents such as alkoxy and halogens and includes esters, amides and hydroxy substituents. Table 7.3 gives some examples. These include cases of introduction of 3-acetic acid, 3-acetamide, 3-(2-aminoethyl)- and 3-(2-hydroxyethyl)- side-chains, all of which are of special importance in the preparation of biologically active indole derivatives. Entry 11 is an efficient synthesis of the non-steroidal anti-inflammatory drug indomethacin. A noteworthy feature of the reaction is the... 

Tire purpose of this chapter is to review the chemistry of the nitro-1,5-, -1,6-, -1,7-, and -1,8-naphthyridines (1) [nitro-2,6- and nitro-2,7-naph-thyridines (2) are unknown], with special attention to the results obtained in the laboratories of both authors. Tliis article mainly refers to the synthesis and reactivity of the nitronaphthyridines their physical and spectroscopic properties and biological activity are only covered briefly. For the convenience of the reader a table listing melting points of (di-)nitronaph-thyridines and some derivatives is included (Table III). Tire literature to about 1998 has been covered. 

The most widely studied interactions between biologically active ligands and organotin(lV) cations relate to the amino acids and their derivatives (N- or S-protected amino acids and peptides), though new data on several of the most commonly occurring amino acids are still being published. This is specially true for aqueous speciation studies. Nice and very detailed reviews were published in this area by Molloy and Nath. ... 

A current area of interest is the use of AB cements as devices for the controlled release of biologically active species (Allen et al, 1984). AB cements can be formulated to be degradable and to release bioactive elements when placed in appropriate environments. These elements can be incorporated into the cement matrix as either the cation or the anion cement former. Special copper/cobalt phosphates/selenates have been prepared which, when placed as boluses in the rumens of cattle and sheep, have the ability to decompose and release the essential trace elements copper, cobalt and selenium in a sustained fashion over many months (Chapter 6). Although practical examples are confined to phosphate cements, others are known which are based on a variety of anions polyacrylate (Chapter 5), oxychlorides and oxysulphates (Chapter 7) and a variety of organic chelating anions (Chapter 9). The number of cements available for this purpose is very great. 

For the last 50 years many scientists have drawn special attention to nitrones due to their successful application as building blocks in the synthesis of various natural and biologically active compounds, of stable nitroxyl radicals, and of other important products for special purposes such as spin traps for the study of radical processes including those that take place in biological systems, and they also found use as both, modifiers and regulators of molecular weight in radical polymerization. 

Abstract. This article describes recent achievements of my research group in the Leibniz-Institut fiir Katalyse e.V. in the area of applied homogeneous catalysis for the synthesis of biologically active compounds. Special focus is given on the development of novel and practical palladium and copper catalysts for the functionalization of haloarenes and haloheteroarenes. 

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