Pyrazofurin
Pyrazofurin (Pyrazomycin) is a natural product present in Streptomyces candidus, a Ribavirin derived nucleoside analog. It has antibiotic, antiviral, and anti-cancer properties but due to extreme side effects, it was not effective in human clinical trials. Nevertheless, it continues to be the focus of ongoing research as a possible 2019-nCoV drug, or as a blueprint for improved synthetic derivatives [16-22].