Tetroses Rarely Existing in Nature

D-Erythrose (1) and D-threose (2) are rare sugars, monosaccharides (with 4 carbon atoms) found only in small amounts in nature. In plants and microorganisms, 1 is converted to D-erythrose-4-phosphate (4EP) by phosphorylation and then used in heptose phosphate pathway or shikimate biosynthesis pathway.¹⁾ Moreover, 1 has proved to an inhibitor of tumor cell growth.²⁾ It has been reported that 2 suppresses mannitol dehydrogenase.³⁾