Alkaloids

Abstract

Alkaloids are organic compounds containing nitrogen usually in the heterocyclic ring. True alkaloids are derived from different amino acids. Tropane alkaloids, pyrrolidine alkaloids and pyrrolizidine alkaloids are derived from the amino acid ornithine; pyridine, piperidine, quinolizidine, indolizidine, and Lycopodium alkaloids from aspartate/lysine; isoquinoline alkaloids from tyrosine; imidazole alkaloids from histidine; indole and quinoline alkaloids from tryptophan; and quinazoline alkaloids are anthranilic acid derived. Protoalkaloids are also derived from amino acids, but the nitrogen atom is not present in the heterocyclic ring. Pseudoalkaloids are nitrogen containing metabolites in which the nitrogen is introduced at a late stage by transamination. Many alkaloids have activities against different herbivores to protect the plant. Alkaloids have pharmacological properties. Many of the alkaloids have biological properties such as protection of the heart and liver and act against hypercholesterolemia, hyperglycemia, nervous and hormonal disorders, and cancers. Some of the alkaloids are used clinically as drugs for treatment of different ailments.