Alkaloids one

Alkaloids are nitrogen-containing compounds found mainly in plants, though also in fungi, animals, and bacteria. They often have significant physiological effects, such as stimulating or depressing the nervous system. Alkaloids are used in medicine (e.g., morphine for pain relief, quinine for malaria), but some can also be toxic (e.g., nicotine, atropine). They are classified into various types based on their chemical structure, including indole, tropane, and purine alkaloids. Many alkaloids serve ecological roles, like deterring herbivores, and some are psychoactive or addictive.