Editorial [Hot Topic: Nucleotides and Nucleosides (Guest Editor: Dr. Li-he Zhang)]

Over the last decade, small molecule nucleoside and nucleotide drugs have attracted much attention due to a remarkable increase for the treatment of viral diseases. Currently more than 20 drugs fall into this category. Nucleoside antiviral drugs are pro-drugs in that they are actively transpored into cells and then activated by cellular kinases to the nucleotide triphosphate (NTP). This NTP is now able to competitively inhibit the enzyme or, more commonly, act as a substrate and be incorporated into the growing polynucleotide chain subsequently prevents (chain-terminates) the further replication of the viral genome. Extensive research efforts have been directed toward the development of nucleoside therapeutics, structural modified nucleoside inhibitors can vary in either (or both) the ribose or base portion of the molecule. In this issue, two chapters describe the development of anti-HBV nucleosides and the chemistry of 7-deazapurine ribonucleosides. RNA interference (RNAi) is a new field to describe the use of small inhibitory double-stranded RNA (siRNA) to target for degradation sequence-specific cellular mRNAs, and as a result to silencing gene expression. With the more recent development of RNAi in mammalian systems, investigators are not only dissecting gene function but also attempting the development of new therapeutic approaches in human genetics and/or infectious diseases. The main challenge for translating the experimental success of siRNA into clinical applications is how to solve the problems of the stability of siRNA in blood and the delivery to target. Three research groups are invited to review the recent developments in this area. Thanks to Current Topics of Medicinal Chemistry for this special issue which makes us to share these very interesting topics.