He has managed to turn an alcohol derived from corncobs and husks into galidesivir, an antiviral drug that targets RNA viruses like Zika and Ebola. Adenosine is also an of the enzyme RNA polymerase, which interferes with the function of certain enzymes in RNA viruses. It binds to the molecules that viruses use to clone themselves, making that function no longer accessible to the virus. There is an extra step in the production of the most powerful form of this drug that ultimately affects the cost. These variants, or stereoisomers, have the same molecular formula as the finished drug, but their atoms form molecules in different arrangements.