BOTANY WITH THE BASICS OF HYDROBOTANY (AQUATIC PLANTS OF UKRAINE) - B.Ye. Yakubenko - 2011

IV. PLANT ANATOMY AND MORPHOLOGY

Secondary Plant Metabolites

Alkaloids

This group comprises heterocyclic compounds. Alkaloids are organic nitrogenous substances, predominantly of plant origin. In plants, they occur as salts of malic, tartaric, citric, and other acids. While alkaloids themselves are insoluble in Water, their salts are water-soluble.

Alkaloids exhibit potent physiological effects on Human and Animal organisms. Most of them affect various parts of The Nervous system. For instance, cocaine acts as a narcotic by affecting sensory nerve endings in the Peripheral Nervous System, making it useful for topical anesthesia; curare is a toxic substance that targets motor nerve endings, inducing paralysis. Morphine acts on the Central Nervous System to induce Sleep, and its hydrochloride salt is widely used in medicine as a powerful analgesic.

The Effect of alkaloids on the central nervous system depends on the dosage: low doses stimulate the nervous system, whereas high doses suppress it. Currently, over 1,000 plant alkaloids are known.

Based on The Structure of their nitrogen-containing heterocycle, alkaloids are classified into several groups: pyridine derivatives (ricinine), pyrrolidine derivatives (stachydrine), quinoline and isoquinoline derivatives (quinine and morphine, respectively), and indole derivatives (ergotamine, strychnine, ergosine, ergocristine).

Alkaloid-rich taxa include Representatives of the families Apocynaceae, Papaveraceae, Fabaceae, Ranunculaceae, Rubiaceae, Solanaceae, and Apiaceae. Conversely, they are extremely rare in species belonging to the Rosaceae, Lamiaceae, and Orchidaceae families.