Synthesis of adenine dinucleosides SAM analogs as specific inhibitors of SARS-CoV nsp14 RNA cap guanine-N7-methyltransferase

International audience ; Viral RNA 2’-O-methyltransferases play a crucial role for luring the host cell innate antiviral response during a viral infection by catalyzing either the methylation of the 5’-end RNA cap-structure at 2’-OH of nucleoside N1 or by inducing internal 2’-O-methylation of adenosines within RNA sequence using S-adenosyl-L-methionine (SAM) as the methyl donor. Our goal is to synthetized bisubstrate SAM analogues mimicking the transition state of the 2’-O-methylation of the RNA in order to block viral 2’-O-methyltransferases and struggle against emerging viruses. Here we designed and synthesized five dinucleosides by connecting a 5’-thioadenosine representing the SAM to the 2’-OH of another adenosine unit mimicking the RNA substrate, via various sized sulfur-containing linkers such as alkylthioether linkers, sulfoxide or sulfone derivatives, or a disulfide bond.