Alkaloids are classified alkaloids are classified in several ways.

Alkaloids are classified

alkaloids are classified in several ways.

1-Taxonomic based:

2-Pharmacological based 3-Biosynthetic based 4-Chemical classification

a-Non-heterocyclic Alkaloids(Hordinine,Ephedrine) b-Heterocyclic Alkaloids:

-Pyrrole-Pyrrolidine -Pyrrolizidine

-Pyridine & Piperidine -Tropane

-Quinoline -Iso Quinoline - Aporphine -Indole Alkaloids

In general, this classification is used more.

I-Non-heterocyclic or atypical alkaloids, sometimes called ‘protoalkaloids’ or biological amines

Hordenine, Mescaline, Ephedrine

II. Heterocyclic or typical alkaloids, divided into 14 groups according to their ring structure.

Alkaloids, may have a nitrogen atom which is primary (mescaline), secondary (ephedrine), tertiary (atropine) or quaternary (one of the N atoms of tubocurarine),

1-Pyrrole,

2-Pyrrolidine

3-Pyrrolizidine

4-Pyridine

5- Piperidine 6-Tropane 7-Quinoline 8-Isoquinoline 9-Indole 10-Indolizidine 11-Quinolizidine 12- Aporphine 13- Imidazole 14- Purine

1-Pyrrole and pyrrolidine

Hygrines Coca spp. (Erythroxylaceae);

2. Pyrrolizidine

Senecionine, seneciphylline, etc. Senecio spp.

3. Pyridine and piperidine

Arecoline Areca catechu (Palmae) Lobeline Lobelia spp. (Lobeliaceae)

Pelletierine Punica granatum, the pomegranate (Punicaceae)

Nicotine (pyridine + pyrrolidine) Nicotiana tabacum and other spp. (Solanaceae) Anabasine Nicotiana glauca; Anabasis aphylla (Chenopodiaceae)

4. Tropane (piperidine/N-methyl-pyrrolidine)

Hyoscyamine, Atropa, Datura, Hyoscyamus, Duboisia, Mandragora and Solanaceae) Cocaine Coca spp. (Erythroxylaceae)

Pesudo-pelletierine Punica granatum (Punicaceae) 5. Quinoline

Quinine, quinidine, cinchonine, cinchonidine Cinchona spp. (Rubiaceae), Remijia spp.

(Rubiaceae) 6. Isoquinoline

Papaverine, narceine, narcotine Papaver somniferum (Papaveraceae)

Hydrastine, berberine Numerous genera of the Berberidaceae, Ranunculaceae and Papaveraceae

Emetine, cephaeline Cephaelis spp. (Rubiaceae)

Tubocurarine Curare obtained from plants of Menispermaceae Morphine, codeine Papaver somniferum (Papaveraceae)

7. Aporphine (reduced isoquinoline/naphthalene) Boldine Peumus boldus (Monimiaceae)

8-Indole or benzopyrrole

Ergometrine, ergotamine Claviceps spp. (Hypocreaceae)

Lysergic acid amide, clavine alkaloids Rivea corymbosa, Ipomoea violacea (Convolvulaceae) Physostigmine Physostigma venenosum (Leguminosae)

Ajmaline, serpentine, reserpine Rauwolfia spp. (Apocynaceae) Yohimbine, aspidospermine Aspidosperma spp. (Apocynaceae) Vinblastine, vincristine Catharanthus roseus (Apocynaceae) Calabash curare alkaloids Strychnos spp. (Loganiaceae) Strychnine, brucine Strychnos spp. (Loganiaceae) 8. Quinolizidine

Sparteine, cytisine, lupanine, laburnine Sometimes called ‘the lupin alkaloids’. Occur particularly in the

Leguminosae, subfamily Papilionaceae, e.g. broom. Cytisus scoparius;

dyer’s broom, Genista tinctoria; Laburnum and Lupinus spp.

9-. Indolizidine

Castanospermine Castanospermum australe (Leguminosae), Alexa spp. (Leguminosae) Swainsonine Swainsona spp. (Leguminosae), Loco plants (Leguminosae)

11. Imidazole Pilocarpine Pilocarpus spp. (Rutaceae)

12. Purine Caffeine Tea (Ternstroemiaceae), coffee (Rubiaceae), maté (Aquifoliaceae), guarana

(Sapindaceae), cola nuts (Sterculiaceae) Theobromine Cocoa (Sterculiaceae)

13. Steroidal (some combined as glycosides)

Solanidine (glycoside = solanine) Shoots of potato (Solanaceae), etc.

Veratrum alkamine esters and their glycosides Veratrum spp. and Schoenocaulon spp.

(Liliaceae)

Conessine Holarrhena antidysenterica (Apocynaceae) Funtumine Funtumia elastica (Apocynaceae)

14. Terpenoid

Aconitine, atisine, lyctonine, etc. Aconitum and Delphinium spp. (Ranunculaceae)

Physicochemical properties:

-Solid crystalline compound (exception are: coniine and Nicotine are liquid (It doesn't have Oxygen in their structure).

-Colorless compound (exception are berberine (yellow) Alkaloids are solid crystalline substances,

Alkaloid salts, as a rule, are soluble in water and

Slightly soluble in organic solvents. The solubility of alkaloids and their salts is of pharmaceutical importance.

Tests for alkaloids

There are several general reagents, which may be used to test the presence of alkaloids or to help their identification. Some of these reagents are as follows.

A- Colored, water-insoluble complexes of alkaloids are formed with various reagents. It is sensitive and reak with very little alkaloids. they give. These reagents are very sensitive.

1- Bouchardat(Potassium iodo iodide)

2. Mayer’s reagent (potassiomercuric iodide solution) 3. Dragendorff’s reagent (potassium bismuth iodide)

B-They form compounds that crystallize well with the second type of reagent. By examining these crystals, it may be possible to identify and determine the structure of the alkaloid. They can be used in more concentrated alkaloids solutions (such as platinum chloride, picric acid trichloroacetic acid) in 0.1-1% solutions.

C- Can be used in chromatographic methods for the identification of alkaloids.

The same conditions apply to thin layer chromatography. Suitable adsorbents and solvent systems in different alkaloids can be found by testing. Dragendorf is used as reagent.

Extraction of alkaloids

There are several methods that can be used for the extraction of the alkaloids.

However, the common procedures are largely based on:

(1) the basic structure of most alkaloids;

(2) ability to form salts with acids;

(3) the ease by which the free bases can be liberated from their salts by alkalinization (4) the solubility of the alkaloids and their salts in water and various organic solvents.

a) Alkaloids are mostly used in the plant to contain mineral or organic acids.

salt, sometimes also combined with tannin.

b) Basic alkaloids are insoluble in water, soluble in organic solvents.

c) Alkaloids in the form of salt do not dissolve in organic solvents, but dissolve in water.

Alkaloids are generally extracted from plants by two methods.

1-Extraction with organic solvent in alkaline

to plant material add alkali solution (ammonium, sodium hydrocarbonate or carbonate).

Alkaloids bases are extracted by organic solutions. Purification achieve by transferring alkaloids to salts and then to bases. Operation of purification repeat few times.

2.Extraction with acidic alcohol

to plant material add water or ethanol with few drops of tartaric acid. All alkaloids forms salts with tartaric acid. For purification to this extract add base and all alkaloids form bases, which obtained by organic solutions. Purification proceure repeat few times. Then solvent

separated from alkaloids. after that the compound/s is separated from total alkaloids Quantitative methods of alkaloids;

Gravimetric Method- Tea caffeine MT Titrimetric Method- (Total alk. quan. met.) Colorimetric Method

UV Spectrophotometric

Chromatographic Methods (HPLC,GC )