Biosynthesis of (2-nitroethyl)benzene and (Z)- and (E)-(2-nitroethenyl)benzenes from (Z)- and (E)-phenylacetaldoximes and phenylacetonitrile; defense allomone of Eutrichodesmus elegans (Miyosi) and E. armatus (Miyosi) [Polydesmida: Haplodesmidae]

Abstract

The defense allomones of two haplodesmid millipedes, Eutrichodesmus elegans (Miyosi) and E. armatus (Miyoshi) (Polydesmida: Haplodesmidae), are known as a mixture of the following three nitro compounds: (2-nitroethyl)benzene and (Z)- and (E)-(2-nitroethenyl)benzenes. Administrations of a mixture of ²H-labeled (Z)- and (E)-phenylacetaldoximes and of ²H-labeled phenylacetonitrile as precursors resulted in the same production of three ²H-labeled nitro compounds, [2′-nitroethyl][2,3,4,5,6-²H₅]benzene and [(Z)- and (E)-2′-nitroethenyl][2,3,4,5,6-²H₅]benzenes, in both species. Oxime administration at an appropriate dose resulted in the production of three nitro compounds with similar natural ratios more effectively than nitrile administration. Conversion from oximes to nitrile and vice versa was evidenced during administration. Occurrences of three precursors (Z- and E-oximes and nitrile) were detected sporadically in millipede extracts by selected ion chromatography.