1,5-Anhydro-D-fructose is a breakdown product of starch and glycogen catabolism in bacteria and fungi. Its metabolism in bacteria is shown in the Starch Oligomer Pathway. In white rot fungus and morels, the bifunctional enzyme aldos-2-ulose dehydratase catalyzes the transformation of 1,5-anhydro-D-fructose to ascopyrone M and then to microthecin (Yu et al., 2004). In Peziza echinospora, the 1,5-anhydro-D-fructose intermediate is converted to ascopyrone M and then to 5-epipentenomycin. Ascopyrone M, ascopyrone P, and ascopyrone T are keto-enol tautomers. Ascopyrone T can be nonenzymatically dihydrated to ascopyrone T1 or enzymatically reduced to 2(S)-dihydroascopyrone T (Deffieux G, Vercauteren J, Baute M-A, Neveu A, Baute R, Phytochemistry, 36: 849-852, 1994).