NUCLEIC ACIDS AND RELATED COMPOUNDS 



235 



crotonoside, riboside of 

 isoguanine (Croton tigliutn) 



IBOSYL 



guanos ine (Coffea arabica) 



RIBITYL 

 I 



riboflavin 



Two unusual pyrimidine glucosides occur in vetch {Vicia spp. ), peas, and beets. 

 They are not nucleosides since the glucosyl group is linked through oxygen rather than 

 nitrogen. However, in chemical properties they bear a resemblance to the true nucleo- 

 sides. Structures are given below: 





O-G-LUCOSYL 

 2 



vicin, glucoside of divicin 



O-GLUCOSYL 



convicin, glucoside of 

 4-imidodialuric acid 



The nucleosides are colorless, crystalline compounds, generally more soluble in 

 water than are the free nitrogen bases. Pyrimidine nucleosides are more soluble in water 

 than purine nucleosides. Purine nucleosides are readily hydrolyzed to base and sugar by 



