One of a varied family of alkaline, nitrogen-containing substances, usually plant-derived, reacting with acids to form salts. Normally intensely bitter, alkaloids form a body of substances widely used in drug and herbal therapy. They are usually biologically active and have a toxic potential. The term is more pharmaceutical and medical than chemical since alkaloids come from a variety of otherwise unrelated organic compounds. (Examples: caffeine, morphine, berberine).
n. one of a diverse group of nitrogen-containing substances that are produced by plants and have potent effects on body function. Many alkaloids are important drugs, including *morphine, *quinine, *atropine, and *codeine.
Substances found commonly in various plants. They are natural nitrogenous organic bases and combine with acids to form crystalline salts. Among alkaloids, morphine was discovered in 1805, strychnine in 1818, quinine and ca?eine in 1820, nicotine in 1829, and atropine in 1833. Only a few alkaloids occur in the animal kingdom, the outstanding example being ADRENALINE, which is formed in the medulla of the suprarenal, or adrenal, gland. Alkaloids are often used for medicinal purposes. The name of an alkaloid ends in ‘ine’ (in Latin, ‘ina’).
Neutral principals are crystalline substances with actions similar to those of alkaloids but having a neutral reaction. The name of a neutral principal ends in ‘in’, e.g. digitalin, aloin.
The following are the more important alkaloids, with their source plants:
Aconite, from Monkshood.
Atropine, from Belladonna (juice of Deadly
Nightshade).
Cocaine, from Coca leaves.
Hyoscine, from Henbane.
Morphine, Codeine, from Opium (juice of
Poppy). Thebaine, Nicotine, from Tobacco. Physostigmine, from Calabar beans. Pilocarpine, from Jaborandi leaves. Quinidine, from Cinchona or Peruvian bark. Strychnine, from Nux Vomica seeds.... alkaloids
A group of powerful CYTOTOXIC (anticancer) drugs used to treat acute LEUKAEMIA, LYMPHOMA and some solid tumours such as breast and lung cancers. Originally derived from the periwinkle plant, the latest vinca alkaloid (VINORELBINE) is a semi-synthetic drug. These alkaloids, which are given intravenously, have potentially serious side-effects on the nervous system and also suppress the production of MYELOID cells in the bone marrow.... vinca alkaloids
A type of alkaloid found in many plants of the Composite and Borage families, once termed a Senecio alkaloid. Some of the pyrrolizidine group have been shown to cause several types of liver degeneration and blood vessel disorders. Several deaths have been attributed to improperly identified plant usage of a Senecio, and some of the desert Boraginaceae annuals and Senecio annuals are overtly toxic. Young leaves and spring roots of Comfrey hybrids should be avoided as well. Not all PAs are toxic, but those that are can produce spontaneous necrosis in the liver hepatocytes of a perfectly healthy person.... pyrrolizidine alkaloid
one of a group of *antimitotic drugs (see also cytotoxic drug) derived from the periwinkle (Vinca rosea). Vinca alkaloids are used especially to treat leukaemias and lymphomas; they include vinblastine, vincristine, and vindesine. Vinorelbine is used in the treatment of advanced breast cancer and *non-small-cell lung cancer. Vinflunine is given by intravenous infusion to treat *transitional cell carcinoma. Vinca alkaloids are highly toxic; side-effects include *myelosuppression, peripheral neuropathy, and severe irritation at the injection site.... vinca alkaloid
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