The following sections of this BookRags Literature Study Guide is offprint from Gale's For Students Series: Presenting Analysis, Context, and Criticism on Commonly Studied Works: Introduction, Author Biography, Plot Summary, Characters, Themes, Style, Historical Context, Critical Overview, Criticism and Critical Essays, Media Adaptations, Topics for Further Study, Compare & Contrast, What Do I Read Next?, For Further Study, and Sources.
(c)1998-2002; (c)2002 by Gale. Gale is an imprint of The Gale Group, Inc., a division of Thomson Learning, Inc. Gale and Design and Thomson Learning are trademarks used herein under license.
The following sections, if they exist, are offprint from Beacham's Encyclopedia of Popular Fiction: "Social Concerns", "Thematic Overview", "Techniques", "Literary Precedents", "Key Questions", "Related Titles", "Adaptations", "Related Web Sites". (c)1994-2005, by Walton Beacham.
The following sections, if they exist, are offprint from Beacham's Guide to Literature for Young Adults: "About the Author", "Overview", "Setting", "Literary Qualities", "Social Sensitivity", "Topics for Discussion", "Ideas for Reports and Papers". (c)1994-2005, by Walton Beacham.
All other sections in this Literature Study Guide are owned and copyrighted by BookRags, Inc.
Alkaloids are nitrogen-containing biochemicals, most of which are natural substances extracted from certain species of plants. The word "alkaloid" is derived from: "like an alkali" (or "base") ( when first discovered by chemists, these botanical chemicals were referred to as "vegetable alkalis." Alkaloids are usually extracted from plants using an alcohol solvent, such as ethanol. Alkaloids vary greatly in their chemical complexity and reactivity, and some show great physiological activity when ingested by animals.
One familiar example of an alkaloid is nicotine, obtained from tobacco (Nicotiana tabacum), a herbaceous plant in the nightshade family (Solanaceae). In small doses, such as those obtained by smoking tobacco in cigarettes, nicotine is a highly addictive stimulant of the nervous system. In higher doses nicotine can be extremely toxic, and in the form of nicotine sulfate it is used as an insecticide.
Other alkaloids are used as medicines or as highly addictive, recreational drugs. These include codeine, heroin, morphine, and opium, addictive narcotics derived or manufactured from the sap of the opium poppy ( Papaver somniferum). Cocaine is another natural alkaloid, derived from the foliage of coca shrubs (Erythroxylon coca and related species), and used as a stimulant and local anaesthetic. The alkaloids atropine and scopolamine are drugs derived from the belladonna plant (Atropa belladonna). A final example is quinine, a bitter-tasting, anti-malarial alkaloid extracted from cinchona trees (Cinchona ledgeriana and related species).