ALKALOIDS-BySweksha SinhaUpasana MahajanSahithi VinjamuriRoli GuptaKavin D.EWhat are Alkaloids?Alkaloidsare a group of naturally occurringchemical compounds, that contain mostlybasic nitrogen atoms.They are produced by a large variety of organisms , includingbacteria,fungi,plants, andanimals, and are part of natural products(also calledsecondary metabolites).They are found in opium poppy and tobacco plant.Pure alkaloid extracts are usually bitter, colourless solids.
ExamplesThe first individual alkaloid,morphine, was isolated in 1804 frompoppy(Papaver somniferum).The most common examples of alkaloids are caffeine, nicotine, quinine, cocaine, and morphine, reserpine.
HistoryThe studies of alkaloids began in the 19th century. In 1804, the German chemist Friedrich Sertrner isolated from opium a "soporific principle which he called "morphium" in honor of Morpheus, the Greek god of dreams. A significant contribution to the chemistry of alkaloids in the early years of its development was made by the French researchers who discovered quinine (1820) and strychnine (1818).The first complete synthesis of an alkaloid was achieved in 1886 by the German chemist Albert Ladenburg.Now, more than 12,000 alkaloids had been identified.
Friedrich Sertrner, the German chemist who first isolated morphine from opium.Distribution in NatureAlkaloids are generated by various living organisms, especially by higher plants .Depending on the type of plants, the maximum concentration is observed in the leaves (black henbane), fruits or seeds (Strychnine tree), root (Rauwolfia serpentina) or bark (cinchona).Beside plants, alkaloids are found in certain types of fungi and in animals ,many marine organisms also contain alkaloids
BiosynthesisWays of alkaloid biosynthesis are too numerous and cannot be easily classified. However, there are a few typical reactions involved in the biosynthesis of various classes of alkaloids. One of them is Synthesis of Schiff bases. Schiff bases can be obtained by reacting amines with ketones or aldehydes. These reactions are a common method of producing C=N bonds.
UsesWhen the first alkaloids were isolated in the 19th century, they immediately found medical application. They are primarily used in medicine, because they can act quickly on specific areas of the nervous system.Alkaloids are the active components of many anesthetics, sedatives, stimulants, relaxants, and tranquilizers.Morphine and cocaine are among the most effective drugs known for temporarily relieving pain without causing loss of consciousness.Colchicineis used as remedy forgout andQuininehas antimalarial action.Nicotine andcaffeineact as stimulants.
Alkaloids present in the skin glands of poisonous frogs is a chemical defense against predation.Prior to the development of a wide range of relatively low-toxic syntheticpesticides, some alkaloids, such as salts of nicotine andanabasine , were used asinsecticides. Their use was limited by their high toxicity to humans
Side Effects Most alkaloids have pronounced effects on the nervous system of humans and other animals Most alkaloids are habit-forming(addictive ) (for example, almost all narcotics are alkaloids) and large doses can be poisonous.Strychnine, used in small doses as a stimulant and a tonic, is highly poisonous. Quinine, used in treating malaria, can cause dizziness if taken in large dosesMost of the alkaloids have Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue). Few also have hallucinogenic properties and cause memory losses.