Remarkable incorporation of the first sulfur containing indole derivative: another piece in the biosynthetic puzzle of crucifer phytoalexins,

Abstract

The first sulfur labelled compound, [(2)H(4),(34)S]indolyl-3-acetothiohydroxamic acid, is incorporated into the phytoalexins cyclobrassinin and spirobrassinin and the indole glucosinolate glucobrassicin, indicating that both biosynthetic pathways are closely related.

Indole glucosinolate breakdown and its biological effects

“…Assuming that indole phytoalexins in B. juncea are synthesized by a similar pathway, IAN production would be induced by L. maculans infection. In contrast to previous suggestions inspired by structural similarity, other indole phytoalexins are also biosynthesized independently of indole glucosinolates, from the shared precursor indol-3-ylacetaldoxime (Pedras et al 2002;Glawischnig et al 2004;Pedras et al 2007) and from indol-3-ylacetothiohydroxamic acid (Pedras and Okinyo 2008).…”

“…In vivo, metabolism of IAN to IAA in rutabaga (Brassica napus ssp. rapifera) tubers was apparently followed by oxidative chain shortening to indole-3-carboxylic acid and its ester, methyl indole-3-carboxylate (Pedras and Okinyo 2008) (Fig. 2).…”

Phytoalexins from Brassicaceae: News from the front

“…Based on this hypothesis, isotopically labeled ( 2 H and 34 S) indolyl-3-acetothiohydroxamic acid (51) was synthesized and administered to UV-irradiated rutabaga tubers (B. napus ssp. rapifera) (Pedras and Okinyo, 2008). Remarkably, incorporation of indolyl-3-acetothiohydroxamic acid (51) into cyclobrassinin (6), spirobrassinin (20) and glucobrassicin (52) was observed.…”

Indolic glucosinolates at the crossroads of tryptophan metabolism

“…Until recently, the simplest IG, indol-3-ylmethyl glucosinolate (I3M), has been thought to be converted by hydroxylation and/or methoxylation to 4-hydroxyindol-3-ylmethyl, 4-methoxyindol-3-ylmethyl, and 1-methoxyindol-3-ylmethyl glucosinolates. However, recent work suggests that these more complex IGs are synthesized from an earlier intermediate common to all IGs and not from I3M (Pedras and Okinyo 2008). These different IGs probably have distinct roles and regulation (Kim and Jander 2007), but for the purposes of this review we will treat them as one IG class.…”