[Degradation of antipyrin by pyrazon-degrading bacteria (author's transl)]

Bacteria with the ability to grow on pyrazon as sole source of carbon were isolated from soil. They also are able to grow on antipyrin. Then three metabolites of antipyrin can be isolated from the culture fluid which were identified as 2,3-dimethyl-1-(cis-2,3-dihydro-2,3-dihydroxy-4,6-cyclohexadiene-1-yl)-pyrazolone (5) (I), as 2,3-dimethyl-1-(2,3-dihydroxyphenyl)-pyrazolone (5) (II) and as 2,3-dimethyl-pyrazolone (5) (III), respectively. Compound I and II were used as substrates for enzyme studies. A dioxygenase catalyzes the enzymatic conversion of antipyrin into compound I. In the presence of NAD as cosubstrate compound I is transformed into compound II by a dehydrogenase. A pure preparation of metapyrocatechase from pyrazon-degrading bacteria converts compound II into the dephenylated heterocyclic moiety of antipyrin (III) and into 2-pyrone-6-carboxylic acid. Based on the results of the enzymatic studies a pathway for the degradation of antipyrin is proposed.