Changes in the steroidal alkaloid solasodine during development of Solanum nigrum and Solanum incanum

All tested organs of Solanum nigrum and Solanum incanum elaborated solasodine, but the levels varied widely. In both species, the smallest leaves showed the highest alkaloid concentration. Maximum levels in S. incanum leaves were greater than twice those in S. nigrum. The absolute amount of alkaloid per leaf increased during leaf development whereas the concentration declined. The pattern of change in leaf alkaloid concentration with increasing age of the plant was different in the two species. The concentration of alkaloid in roots was higher than in the stem in S. nigrum, but initially similar to stem levels in S. incanum. Both organs showed alkaloid accumulation with time, although root levels inexplicably fell in S. incanum after 20 weeks. Small unripe fruits of S. nigrum had a high concentration of solasodine, but both the concentration and the absolute amount per fruit decreased with fruit maturation. The concentration and absolute amount of alkaloid also diminished in fruits of all developmental stages with increasing age of the plant. S. incanum plants did not produce fruits during the study period. (C) 1997 Elsevier Science Ltd.