Alkaloid
An alkaloid is, strictly speaking, a naturally occurring amine produced by a plant, but amines produced by animals and fungi are also called alkaloids[1]. Many alkaloids have pharmacological effects on humans and other animals. The name derives from the word alkaline; originally, the term was used to describe any nitrogen-containing base. Alkaloids are usually derivatives of amino acids, and many have a bitter taste. They are found as secondary metabolites in plants (e.g. potatoes and tomatoes), animals (e.g. shellfish) and fungi. Many alkaloids can be purified from crude extracts by acid-base extraction. While many alkaloids are poisonous, some are used medicinally as analgesics (pain relievers) or anaesthetics, particularly morphine and codeine, and for other uses.
Alkaloid classifications
Alkaloids are usually classified by their common molecular feat, based on the metabolic pathway used to construct the molecule. When not much was known about the biosynthesis of alkaloids, they were grouped under the names of known compounds, even some non-nitrogenous ones (since those molecules' structures appear in the finished product; the opium alkaloids are sometimes called "phenanthrenes", for example), or by the plants or animals they were isolated from. When more is learned about a certain alkaloid, the grouping is changed to reflect the new knowledge, usually taking the name of a biologically-important amine that stands out in the synthesis process.
· Pyridine group: piperine, coniine, trigonelline, arecaidine, guvacine, pilocarpine, cytisine, nicotine, sparteine, pelletierine.
· Pyrrolidine group: hygrine, cuscohygrine, nicotine
· Tropane group: atropine, cocaine, ecgonine, scopolamine, catuabine
· Quinoline group: quinine, quinidine, dihydroquinine, dihydroquinidine, strychnine, brucine, veratrine, cevadine
· Isoquinoline group: The opium alkaloids (morphine, codeine, thebaine, Isopapa-dimethoxy-aniline, papaverine, narcotine, sanguinarine, narceine, hydrastine, berberine), emetine, berbamine, oxyacanthine
· Phenethylamine group: mescaline, ephedrine, dopamine, amphetamine
· Indole group:
o Tryptamines: DMT, N-methyltryptamine, psilocybin, serotonin
o Ergolines: the ergot alkaloids (ergine, ergotamine, lysergic acid, etc.)
o Beta-carbolines: harmine, harmaline, yohimbine, reserpine
o Rauwolfia alkaloids: Reserpine
· Purine group:
o Xanthines: caffeine, theobromine, theophylline
· Terpenoid group:
o Aconite alkaloids: aconitine
o Steroids: solanine, samandaris (quaternary ammonium compounds): muscarine, choline, neurine
· Vinca alkaloids: vinblastine, vincristine. They are antineoplastic and binds free tubulin dimers thereby disrupting balance between microtuble polymerization and delpolymerization resulting in arrest of cells in metaphase.
· Miscellaneous: capsaicin, cynarin, phytolaccine, phytolaccotoxin



Physicochemical Properties of Alkaloids
· colourless,crystalline,non-volatile solids that are insoluble in water but soluble in organic solvents such as ethanol,ether,chloroform,etc.
· Molecular weight 100-900
· Those without oxygen atoms in the structure are usually liquid at ordinary temperature (e.g. nicotine, sparteine, coniine)
· Those with oxygen atoms are crystalline (e.g. berberine -> yellow)
· Most are optically active (usually laevorotatory), but not those from the purine group
· Basicity depends on the availability of lone pairs of electrons on the N atom & the type of heterocycle and substituents.
· Ability to form salts with mineral acids (e.g. with HCl, H2SO4, HNO3) or organic acids (e.g. tartrates, sulfamates, maleates)

AOA,
here is a v small contribution for chemistry optional paper. If any one is interested to opt for CHEMISTRY plz join this thread. It can be scoring if prepared prperly.

Well done BIBI....

I want to know some of alkaloid reactions, if you know about it...
my optional is not chemistry, but still i need answer of these Questions..

Nicotine( an alkaloids) obtained from the tobbaco leaves, it reacts with
Wagner's reagent, mayer's reagent and Hager's reagent to give ppt of different colour,
if i m not wrong the color of ppt is Red , yellow and off white..

So my Question is what is main chemical changes take place during these chemical reaction and what is chemical formula of these ppt...

DO YOU KNOW???

i have searched it every where, (almost whole library) but can't find answer... if you know answer or if you can ask it to your teacher for me... Do tell me as early as possible...


if you are here, plz do reply me

whether you can solve it. or not..
Plzzzzzzz tell me as early as possible...

I need answer urgently....

Thanx.........

regards....

__________________
"Prejudice is the opinion without judgement"

I m M.Sc. in chemistry. But don t know these reactions. Alkaloids were not included in syllaus. I have asked this question from my teacher via email. So wait plz.

aoa,
mr pharm
i have some information for u. Log on to this web site, hopefully u will find ur answer.
http://www.scribd.com/people/login?just_login=1

Thanx BIBI...

BUT i m not Mr: I m Miss

__________________
"Prejudice is the opinion without judgement"

Oh v nice. Same is here. I think u r a Pharmacist. More learned person than me. Alkaloids, Petrochemicals, ceramics, fermentation, were not included in our msc syllabus. y included in css syllabus?