ABSTRACT
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Indole alkaloids are so-called because they incorporate an indole ring system 1 in their molecular structure. All indole alkaloids are biogenetically derived from tryptophan 2 and therefore contain two nitrogen atoms, one of which is contained within the five-membered part of the indole nucleus. In a few instances, notably the pharmaceutically important alkaloids such as quinine from Cinchona species and camptothecin from Camptotheca acuminata, this five-membered ring is expanded by the inclusion of an extra carbon and the alkaloids chemically are classified as quinolines 3 rather than indoles, although their biogenetic origins are the same. The chemistry and biological activity of indole alkaloids have received much attention over the last 50 years and several monographs1,2 and detailed reviews* have been published.
