Nucleoside structure

Pteridine, 2-amino-4,6,7-trimethyl-basicity, 3, 267 Pteridine, 2,2 -anhydro-nucleosides, structure, 3, 283 Pteridine, 2,5 -anhydro-nucleosides structure, 3, 283 Pteridine, 6-aryl-synthesis, 3, 316 Pteridine, 7-aryl-synthesis, 3, 314... 

For the sake of simplicity in illustrating A -glycoside formation in DNA, we shall show the type of bonding involved for the sugar and base components only (i.e., the deoxyribose nucleoside structure). Attachment of 2-deoxyribose is through a NH group to form the /3-N-deoxyribofuranoside (Section 20-5) ... 

It is not unlikely that more antibiotic substances having nucleoside structures will be found in Nature. Already, just in the realm of the purine nucleosides, three antibiotic substances, nebularine,7,176 cordycepin,6 and puromycin8,173 have been isolated from natural sources. 

Extensive work has been reported on the chemistry of polyphosphates, in particular that of dinucleoside and sugar nucleoside pyrophosphates. This reflects the reliability and flexibility of the phosphoramidate methods which have been developed over the past few years. Similarly, a wide range of oligonucleotide building blocks, incorporating extensive structural modifications when compared to the natural nucleoside structures, have been described. 

Yamamoto, I., Kimura, T., Takeoka, Y., et al. (1987) JV-Substituted oxopyrimidines and nucleosides structure-activity relationship for hypnotic activity as CNS depressant. J. Med. Chem., 30, 2227-2231. 

Etoposide p-gp [140] Sorivudine Nucleoside Structural analogy to zidovudine... 

Antibiotic A201A. Antibiotic A201A (23), produced by S. capreolus, is an A/ - dime thyladenine nucleoside structurally similar to puromycin (19). Compound (23) which contains an aromatic acid and monosaccharide residues (1,4), inhibits the incorporation of amino acids into proteins but has no effect on RNA or DNA synthesis. Compound (23) does not accept polypeptides as does (19), and does appear to block formation of the initiation complex of the 50S subunit. It may block formation of a puromycin-reactive ribosome. 

Trifluorothymidine is a fluorinated pyridine nucleoside structurally related to idoxuridine (55). It has been approved by the U.S. FDA and is a potent, specific inhibitor of replication of HSV-1 in vitro. Its mechanism of action is similar to that of idoxuridine. Like other antiherpes drugs, it is first phos-phorylated by thymidine kinase to mono-, di-, and triphosphate forms, which are then incorporated into viral DNA in place of thymidine to stop the formation of late virus mRNA and subsequent synthesis of the virion proteins. 

Recent methods for the synthesis of nucleoside derivatives which have been tested for anti-HIV activity, or which, because of their structure, may be good candidates for testing are described. The nucleoside derivatives considered in this review are 3 -azido-2, 3 -dideoxynucleosides, 2, 3 -dideoxy-3 -fluoronucleosides, 2, 3 -dideoxy-3 -C-substituted nucleosides, 2, 3 -dideoxy-P-D-glycero-pent-2-enofuranosyl nucleosides, 2, 3 -dideoxynucleosides and carbocyclic, acyclic and C-nucleosides. Structure-activity relationships are also considered. 

A nucleoside is an N-glycoside. The pyrimidine or purine base is connected to the anomeric carbon (C-1) of the sugar. The pyrimidines are connected at N-1 and the purines at N-9 (Figure 18.2). Nucleoside structures are numbered in the same way as their component bases and sugars, except that primes are added to the numbers for the sugar part. 

---