An Intermediate in the Synthesis of Glucobrassicins from 3-Indoleacetaldoxime by Woad Leaves

Abstract

Leaves of woad (Isatis tinctoria L.) were found to incorporate efficiently tritiated indoleacetaldoxime and 35S from 35S-l-cystine into glucobrassicin and sulfoglucobrassicin. Time course of incorporation of 35S from 35S-cystine into the glucosinolates indicated that glucobrassicin was formed first and then sulfoglucobrassicin. Simultaneous administration of tritiated indoleacetaldoxime and 35S-cystine gave doubly labeled glucobrassicin and sulfoglucobrassicin. About twice as much 35S was present in sulfoglucobrassicin as compared to glucobrassicin per unit of 3H incorporated, indicating that a second, probably oxidized, atom of 35S was later introduced into sulfoglucobrassicin. However, the 35S incorporated from cystine into both glucosinolates during the first 8 hours of metabolism was almost exclusively in the divalent sulfur moiety. The incorporation patterns of 35S and titritated indoleacetaldoxime into the glucosinolates suggested a fast turnover of glucobrassicin in the metabolizing leaves.