Alkaloids’ wide world: Biological activity, extraction, quantification

Alkaloids represent one of the widest categories of bioactive secondary metabolites with several biological activities, comprising beneficial and harmful effects on human health. They are naturally occurring in a variety of plant species and are categorized mainly from their precursor. Positive and negative biological effects on humans were largely studied in numerous in vivo and clinical studies, but new compounds are continuously discovered and annotated among alkaloid class generating a renewed interest and new research work. Well-known and latest evidence concerning alkaloids' activity is reported together with the recent techniques applied for their extraction in different matrices. Conventional and innovative analytical methods developed for alkaloid characterization are described, reporting limits of detection and quantification and the latest fast technologies based on analysis by sensors. This chapter covers all aspects related to alkaloids classification, biological properties, and their characterization in several types of matrices by traditional and advanced analytical tools.