Skip to Content


Pronunciation: al′kă-loyd

Definition: Originally, any one of hundreds of plant and fungal products distinguished by alkaline (basic) reactions, but now restricted to heterocyclic nitrogenous and often complex structures possessing pharmacologic activity; their trivial names usually end in -ine (morphine, atropine, colchicine). Alkaloids are synthesized by plants and are found in the leaf, bark, seed, or other parts, usually constituting the active principle of the crude drug; they are a loosely defined group, but may be classified according to the chemical structure of their main nucleus. For medicinal purposes, due to improved water solubility, the salts of alkaloids (morphine sulfate, codeine phosphate) are usually used. see also individual alkaloid or alkaloid class.

Synonym(s): vegetable base

Disclaimer: This site is designed to offer information for general educational purposes only. The health information furnished on this site and the interactive responses are not intended to be professional advice and are not intended to replace personal consultation with a qualified physician, pharmacist, or other healthcare professional. You must always seek the advice of a professional for questions related to a disease, disease symptoms, and appropriate therapeutic treatments.
© Copyright 2018 Wolters Kluwer. All Rights Reserved. Review Date: Sep 19, 2016.