Senecionine n-oxide, the primary product of pyrrolizidine alkaloid biosynthesis in root cultures of Senecio vulgaris
Phytochemistry, 26 (6):
1639--1643 (1987)DOI: 10.1016/S0031-9422(00)82261-X
Abstract
Root cultures of Senecio vulgaris synthesize pyrrolizidine alkaloids which are accumulated in the form of their N-oxides. The cultures incorporate biosynthetic precursors, such as arginine, ornithine, isoleucine, putrescine and spermidine, with high efficiency into the alkaloids. Senecionine N-oxide is found to be the primary product of biosynthesis. With putrescine and spermidine incorporation rates of 20-30% are obtained. The N-oxide synthesized does not appear to undergo significant turnover. Tertiary pyrrolizidine alkaloids, if found at all, occur in small amounts in old tissues only. They are derived from the corresponding oxides, and are easily formed spontaneously during alkaloid extraction. The suitability of N-oxides in alkaloid storage is discussed.