ABSTRACT

Alkaloids are laevorotatory basic naturally occurring hetereocyclic organic nitrogen containing compounds which are biosynthesized from amino acids by plants, microorganisms and some animals. Many of them are pharmacologically active and are consequently used as drugs. The main precursors for alkaloid biosynthesis are ornithine, lysine, aspartic acid, phenylalanine, tyrosine and tryptophan. For example the alkaloid in tobacco, nicotine, is derived from ornithine while phenylalanine and tyrosine give rise to simple alkaloids such as ephedrine or more complex ones such as morphine.