Biosynthesis of riboflavin and the role of acetoin (3-hydroxybutan-2-one) in the formation of the o-xylene ring

Abstract

Incorporation experiments with [2-¹³C]pyruvate and [4-¹⁴C]acetoin ([4-¹⁴C]-3-hydroxybutan-2-one), in Eremothecium ashbyii have shown that acetoin (6) is not a precursor of riboflavin. Growth studies with the same organism support this conclusion and indicate that the o-xylene ring and the ribityl side-chain of riboflavin differ appreciably in their biogenetic origins.