Introduction

Abstract

The alkaloids are a group of naturally occurring organic compounds containing nitrogen. Their name, meaning “alkali-like”, was given them because most of them are basic in nature and form salts with acids. Basicity is a common characteristic of organic nitrogen compounds, which can be regarded as derived from ammonia by the substitution of organic radicals for hydrogen. The simple amines are considered a class apart from the alkaloids, although with increasing complexity of structure the dividing line between amine and alkaloid tends to become indistinct. According to one definition, alkaloids contain nitrogen in heterocyclic rings while the nitrogen of amines is aliphatic. Compounds such as colchicine and mescaline would be excluded from the alkaloids by such a definition, but the exclusion seems inadvisable on the basis of historical usage. Introduction of the term “protoalkaloid” [1] for a group of borderline compounds leaves very few compounds unclassified. A few otherwise impeccable alkaloids, such as rutaecarpine and ricinine, that have electron-withdrawing functional groups either adjacent to or conjugated with their nitrogen atoms, do not show the characteristic of basicity.

Glory to God for dappled things —

All things counter, original, spare, strange;

Whatever is fickle, freckled (who knows how?) With swift, slow; sweet, sour; adazzle, dim;

He fathers forth whose beauty is past change:

Praise Him.

Pied Beauty, Gerard Manley Hopkins*