Analysis of indole-3-acetic acid metabolites from Dalbergia dolichopetala by high performance liquid chromatography-mass spectrometry

A mixture of [2-14C1] and [13C6]indole-3-acetic acid was applied to the cotyledons of 6-day-germinated seeds of "jacaranda do cerrado" (Dalbergia dolichopetala) and after 8 hours the seeds were extracted. Analysis of the fractionated extract by reversed-phase high performance liquid chromatography-radiocounting revealed the presence of five radiolabeled metabolite peaks (I-V). After further purification, the individual peaks of radioactivity were analyzed by combined high performance liquid chromatography-steel filter-fast atom bombardment-mass spectrometry. The metabolite fraction V was found to contain [14C1,13C6]indole-3-acetylaspartic acid and unlabeled indole-3-acetylglutamic acid. Analysis of the metabolite fraction II revealed the presence of dioxindole-3-acetylaspartic acid and putative dioxindole-3-acetylglutamic acid as well as putative benzene ring-hydroxylated derivatives of oxindole-3-acetylaspartic acid and oxindole-3-acetylglutamic acid. There was no evidence of significant incorporation of label from [2'-14C1] or [13C6]indole-3-acetic acid into any of these conjugated indoles