The Biosynthesis of Allantoin in Symphytum.

Glycine-2-C¹⁴, hypoxanthine-8-C¹⁴, and urea-C¹⁴ were fed to both leaf disks and sterile root cultures of Symphytum uplandicum (Nyman). In both tissues, hypoxanthine-8-C¹⁴ was largely converted to allantoin, in which the distribution of radioactivity suggested its formation by way of a symmetrical intermediate. In leaf disks, the conversion of glycine-2-C¹⁴ to allantoin was at most very slight. In roots, it was partially converted to allantoin in either tissue. It is concluded that in roots allantoin is synthesised from glycine through purine intermediates. [ABSTRACT FROM AUTHOR]