Chemistry Reference
In-Depth Information
ALKALOIDS
SARAH E. O'CONNOR
Department of Chemistry, Massachusetts Institute of Technology, Cambridge,
Massachusetts
How nature synthesizes complex secondary metabolites, or natural products, can
be studied only by working within the disciplines of both chemistry and biology.
Alkaloids are a complex group of natural products with diverse mechanisms of biosyn-
thesis. This chapter highlights the biosynthesis of four major classes of plant-derived
alkaloids. Only plant alkaloids for which significant genetic information has been
obtained were chosen for review. Isoquinoline alkaloid, terpenoid indole alkaloid,
tropane alkaloid, and purine alkaloid biosynthesis are described here. The chapter is
intended to provide an overview of the basic mechanism of biosynthesis for selected
members of each pathway. Manipulation of these pathways by metabolic engineering
is highlighted also.
Alkaloids are a highly diverse group of natural products related only by the
presence of a basic nitrogen atom located at some position in the molecule.
Even among biosynthetically related classes of alkaloids, the chemical structures
are often highly divergent. Although some classes of natural products have a
recognizable biochemical paradigm that is centrally applied throughout the path-
way, for example, the “assembly line” logic of polyketide biosynthesis (1), the
biosynthetic pathways of alkaloids are as diverse as the structures. It is difficult
to predict the biochemistry of a given alkaloid based solely on precedent, which
makes alkaloid biosynthesis a challenging, but rewarding, area of study.
