siust alkaloids and antibiotics

22
B Syrian P By Dr.Hake n Intern ha em Alanee Provided b ational Co arm by IonsClub.C l Unive ollege S ma Com Team ersity Fo Of Ph Second Yea aco or Scie harma ar ogn ence and acy nos d Tech sy nology 2 y SIUST Provided By Www.IonsClub.Com

Upload: momer

Post on 12-Nov-2014

1.077 views

Category:

Documents


0 download

DESCRIPTION

The book which we get in the 2th year at SIUST university provided by ionsclub.com

TRANSCRIPT

Page 1: SIUST Alkaloids and Antibiotics

B

Syrian

P

By Dr.Hake

n Intern

ha

em Alanee

Provided b

ational

Co

arm

by IonsClub.C

l Unive

ollege S

ma

Com Team

ersity Fo

Of Ph

Second Yea

aco

or Scie

harmaar

ogn

ence and

acy

nos

d Tech

sy

nology

2

y

SIUST Provided By Www.IonsClub.Com

Page 2: SIUST Alkaloids and Antibiotics

1  

:تم وبحمد هللا كتابة ھذا الكتاب بمساعدة جمال الباشا

شذا الفريجات نھاد الحاج سعيد محمد معمر حقي

.مع التنقيح اإلمالئي والعلمي، وتحت إشراف وموافقة الدكتور الفاضل حكيم العاني

.لتصحيحھا في اإلصدارات القادمة [email protected] وإن وجد أي خطأ إمالئي نرجوا ارسال رسالة إلى

ل نبتة ذكرت في الكتاب وبعض الصور التفصيلية عنھا، كما وضع في الھامش شرح ألھم تم إضافة صور ك .بھدف تسھيل المادة على الطالب واالستمتاع بھا. المصطلحات العلمية من أسماء أمراض ومركبات كيميائية

مع تحيات فريق موقع IonsClub.Com

Page 3: SIUST Alkaloids and Antibiotics

2  

Alkaloids Are group of organic compounds containing one or more nitrogen atoms in a heterocyclic ring, found mainly in plants. Many alkaloids have physiological effects that make them useful or valuable medicinal agents. The name proto-alkaloids or amino-alkaloids are sometimes applied to compounds such as ephedrine and colchicines which lack one or more of the properties of typical (true) alkaloids.

Alkaloids

True alkaloids 

Have heterocyclic  ring with nitrogen 

Examples: Quinine, morphine,…… 

Derived from amino acids 

Pseudo‐alkaloids 

Have heterocyclic ring with nitrogen 

Not derived from amino acids

Can be derived form terpenoids 

Examples: Aconite, Taxol.

Proto‐alkaloids 

Don't have heterocyclic ring with nitrogen 

Examples: Ephedrine, Colchicine.

Page 4: SIUST Alkaloids and Antibiotics

3  

Properties of alkaloids: Alkaloids have in common a number of physical and chemical properties.

- For the most part, the free (bases) alkaloids are insoluble or sparingly soluble in water, but the salts formed on reaction with acids are usually soluble in water.

- The free alkaloids are usually soluble in organic solvents(ether, chloroform,…) or other relatively non-polar solvents, in which the alkaloidal salts are insoluble. This property permits a ready means for the isolation and purification of the alkaloids as well as for their quantitative estimation.

- Most of the alkaloids are crystalline solids, although a few are amorphous. An additional few such as coniine, nicotine …., which lack oxygen in their molecules are liquids.

- Alkaloids usually contain at least one nitrogen atom which may exist as a primary amine (RNH2 ), as a secondary amine (R2NH), or as a tertiary amine (R3N), or sometimes as a quaternary amine )N(R 4

+− . - Coloured alkaloids are rare such as Berberine which is yellow and the salt of

Sanguinarine are copper-red. - Alkaloids are found in plants in the free state and as alkaloid salts. - Some alkaloids such as Caffeine have exceptional properties. Caffeine (base) is soluble

in water and in organic solvents. - The alkaloids usually posses a bitter taste.

Tests for Alkaloids: Most alkaloids form salts with heavy metals. These salts or precipitates are usually obtained from neutral or slightly acid solution of the alkaloid, and many of them have characteristic crystal forms. The common alkaloidal reagents include: Mayer's reagent (solution of potassium mercuric iodide), Wagner's reagent (solution of iodine in potassium iodide), or by Dragendorff's reagent (solution of potassium bismuth iodide). Mayer's reagent gives cream color ppt. , Wagner's forms reddish-brown ppt., and Dragendorff's gives orange-red colour or ppt. Caffeine and other purine bases don't give ppt. with these alkaloidal test solution. Caffeine can be detected by mixing with a very small amount of potassium chlorate and a drop of hydrochloric acid, evaporating to dryness and exposing the residue to ammonia vapor, a purple colour is produced with caffeine and other purine derivatives. This is known as the Murexide test.

Page 5: SIUST Alkaloids and Antibiotics

4  

Pharmacological activity: The pharmacological action of alkaloids varies widely. Some (morphine, codeine) are analgesics and narcotics, whereas others ( strychnine, brucine ) are central stimulants. Some ( atropine) are mydriatics1, whereas others (pilocarpine, physostigmine) are miotics. Some (ephedrine) cause a rise in blood pressure, but others ( reserpine) produce a decrease in hypertension. The names of the alkaloids are obtained in various ways:

1- From the generic name of the plant producing them. Examples: atropine 2- From the specific name of the plant example: Cocaine, Belladonnine. 3- From the common name of the drug producing them. Example: Ergotamine. 4- From the physiological activity such as: emetine. 5- Occasionally from the discoverer name such as Pelletierine.

The names of all alkaloids should end in (ine). Among the plant families rich in alkaloids are: Apocynaceae, Papaveraceae, Rubiaceae, Solanaceae, Berberidaceae and Ranunculaceae. Extraction of Alkaloids: Method A: the powdered material is moistened with water and mix with lime ( base such as Ca(OH)2 to liberate the Alkaloids ( if exist in the plant as salts). Extraction is then carried out with water immiscible organic solvents (Ether, chloroform, petroleum ether, etc…) the concentrated organic liquid is then shaking with aqueous acid (dilute acid) and allowed to separate in a separatory funnel. Alkaloids' salts are now in aqueous layer, while many impurities remain behind in the organic layer. Scheme of method A: Method A: Powdered drug + base Extract with ether or chloroform Concentrate Chloroform layer Shake with dilute acid Separatory funnel

                                                            pertaining to abnormal dilation of the pupil of the eye 1  

Moistened 

H2O 

Filter 

Chloroform layer contains the impurities 

Aqueous-acid layer contains the alkaloid salt 

Evaporate and crystallize the alkaloid 

Page 6: SIUST Alkaloids and Antibiotics

5  

Method B: The powdered material is extracted with aqueous alcohol mixture containing dilute acid. Pigments and other unwanted materials are removed by shaking with water immiscible organic solvent ( ether, chloroform, petroleum ether….) the free alkaloids are then precipitated by the addition of excess ammonia solution 5% NH4OH and separated by extraction by gentle shaking with water immiscible organic solvent. Powdered drug Filter

Make alkaline with 5%NH4OH

Chloroform layer contains the free alkaloid ( base).

Evaporate and crystallize

Aqueous basic layer contains unwanted substance

Extract with acidified aqueous alcohol

Concentrate Shake gently with chloroform in a separaotry funnel

Aqueous acid layer contains the alkaloid salts.

Gently shake with chloroform in a separaotry funnel

Chloroform layer contains pigments and other unwanted materials

Page 7: SIUST Alkaloids and Antibiotics

6  

Structure and Classification: Alkaloids are usually classified according to the nature of the basic chemical structures from which they are derived. The main classes and their basic chemical structures are shown as follows:

1- Pyridine-Piperidine alkaloids 2- Tropane alkaloids 3- Quinoline alkaloids 4- Isoquinoline alkaloids 5- Indole alkaloids 6- Imidazole alkaloids 7- Alkaloidal amines 8- Purine bases 9- Steroidal alkaloids

Page 8: SIUST Alkaloids and Antibiotics

7  

Pyridine1-Piperidine2 Alkaloids On reduction, the tertiary base (Pyridine) is converted into the secondary base ( Piperidine). These two nuclei form the basis of this group which is sometimes divided into three subgroups:

1- Derivatives of Piperidine including Lobeline from Lobelia. 2- Derivatives of nicotinic acid including Arecoline from Areca. 3- Derivative of both Pyridine and Pyrrolidine including nicotine from

Tobacco. The important drugs containing Pyridine-Piperidine alkaloids are:

1- Areca, Areca nut: is the dried ripe seed of Areca catechu F. Arecaceae (or Palmae)

Areca containing alkaloids which are reduced Pyridine derivatives. The main and most physiologically active alkaloid is Arecoline. Areca is an anthelmintic3 in veterinary practice and used as a vermicide4 and taeniafuge5.

2- Lobelia, or Indian tobacco: is the dried leaves and tops of Lobelia

inflata F.Lobeliaceae. The main alkaloid is Lobeline. Lobeline produces similar but weaker pharmacologic effect, to those of nicotine on perepheral circulation, neuro muscular junctions, and the CNS. For this reason, Lobeline was formerly used to aid breaking the tobacco habit (smoking deterrents).

                                                            

1 The simplest one is pyridine itself (C5H5N). Natural compounds with pyridine rings include niacin and pyridoxine, the tuberculosis drug isoniazid, and several plant products (e.g., nicotine). Pyridine is used as a raw material for various drugs, vitamins, and fungicides and as a solvent. Because it has a nauseating odour and a burning taste, it is added to ethanol and antifreezes to make them undrinkable.    2 Colorless liquid compound: a colorless liquid compound that has a peppery odor resembling ammonia. Use: manufacture of rubber and epoxy resins.  3 Describes a natural or pharmaceutical substance that destroys or expels intestinal parasitic worms 4 A substance used to kill worms 5 A drug or other agent that expels tapeworms from the body 

Areca: Fruiting specimen

Areca Palm Fruit at

Kolkata,India  

Lobelia 1887 illustration

 

Page 9: SIUST Alkaloids and Antibiotics

8  

3- Nicotine: is a Pyridine-Pyrrolidine alkaloid obtained from the dried leaves of the tobacco plant Nicotiana tabacum F.Solanaceae.

Chronic use of Nicotine may result in physiologic and physical dependence. Nicotine chewing gum and nasal spray are intended to help smokers who want to give up smoking.

Tropane Alkaloids The main alkaloids of medicinal importance in this group are: (-)-Hyoscyamine, Hyoscine (Scopolamine). These compounds are esters of hydroxytropanes (or hydroxytropines) and various acids such as tropic acid. Atropine and Scopolamine are used as antispasmodic to relieve spasms of the gastrointestinal tract (GIT) and to reduce gastric motility1, gastric and respiratory secretions, and as mydriatic2 drug.

                                                            1 capacity to move 2 pertaining to abnormal dilation of the pupil of the eye 

Page 10: SIUST Alkaloids and Antibiotics

9  

 

Illustration from Köhler's Medicinal Plants 1887 

Atropine is an anti-dote in cases of poisoning caused by organophosphate insecticides. Toxicity symptoms that can occur during the therapeutic use of Atropine, Scopolamine and Belladonna extract (Tropane alkaloid) are skin rash1, skin flushing2, mouth dryness, difficulty in urination and blurred vision3. Atropine and Scopolamine are used to a large extent in ophthalmic practice to dilate the pupile of the eye. Drugs containing Tropane alkaloids:

1- Belladonna: consists of the dried leaves and flowering tops of Atropa belladonna F.Solanaceae.

Belladonna contains from 0.3- 0.6% of alkaloids, the chief alkaloid is Hyoscyamine. Small amounts of other bases are found in the root but not in the leaves. These include Belladonnine, Scopolamine,…. etc. Belladonna alkaloids are used as antispasmodic and sedative drug.

2- Stramonium: consists of the dried leaves or dried leaves and flowering tops of Datura stramonium and its varities, Family Solanaceae.

The drug contains Hyoscyamine and Hyoscine. Uses is the same or similar to belladonna alkaloids.

                                                            1 inflammation or eruption on the skin 2 Redden skin 3 Foggy vision 

   Flowers of belladonna. 

   Berries of belladonna. 

   Leaves of belladonna. 

Datura stramonium

Page 11: SIUST Alkaloids and Antibiotics

10  

3- Hyoscyamus or Henbane: consists of the dried leaves or dried leaves and flowering tops of Hyoscyamus niger F. Solanaceae.

The drug contains Hyoscyamine and Hyoscine alkaloids. The alkaloids of Hyoscyamus has similar pharmacological activity to that of belladonna and datura

4- Coca: is the dried leaves of Erythroxylum coca F.Erythroxylaceae. Coca leaves contain mainly cocaine alkaloid. Cocaine and its salts were used as local anaesthetics1, but because of their toxicity and addictive properties, their use is now entirely confined to ophthalmic, ear, nose and throat surgery.

                                                            

1 anesthetic: substance that dulls pain 

                                                                           Henbane                                                                            Henbane in flower                                  

 

 Coca 

Page 12: SIUST Alkaloids and Antibiotics

11  

Quinoline Alkaloids Alkaloids containing Quinoline as their basic nucleus include those obtained from Cinchona. Cinchona: consists of the dried bark of the stem or of the root of Cinchona succirubra, or its hybrids, family Rubiaceae The most important alkaloids of Cinchona are: Quinine, Quinidine, Cinchonine and Cinchonidine.

- Quinine is used for the treatment of Malaria1 in many parts of the world.

- Quinidine is employed for the prophylaxis2 of cardiac arrhythmias3 and for the treatment of arterial fibrillation4, it also has antimalarial properties and like Quinine, is effective against chloroquine resistant organisms.

                                                            1 An infectious disease caused by a parasite that is transmitted by the bite of infected mosquitoes. Common in tropical        countries, the disease is characterized by recurring chills and fever. 2 Treatment to prevent disease: a treatment that prevents disease or stops it from spreading, e.g. vaccination 3  An irregularity in the rhythm of the heartbeat 4 Rapid irregular heartbeat 

Page 13: SIUST Alkaloids and Antibiotics

12  

Isoquinoline Alkaloids The isoqunoline structures occurs in a number of alkaloids in widely separated plant families. They represent the largest group of plant alkaloids and there is a great variation in their chemical structures. Some of the important isoquinoline subgroups are:

1- Morphinans, such as Morphine and Codeine. 2- Benzylisoquinoline, such as Papaverine.

Drugs containing isoquinoline alkaloids:

1- Opium: is the air-dried milky exudate1 (or Latex2) obtained by incision from the unripe capsules of the opium poppy Papaver somniferum or its varieties, family Papaveraceae. Opium contains more than 30 alkaloids. The most important of these are: Morphine, Codeine and Papaverine.

Morphine has both a phenolic and alcoholic hydroxyl group and when acetylated forms diacetylmorphine or called Heroin.

Codeine is an ether of morphine ( methylmorphine ). The solubility of morphine in sodium hydroxide is explained by its phenolic nature. Conversely , codeine is precipitated by sodium hydroxide.

Morphine and codeine are morphinan isoquinoline derivatives. Morphine and its salts are classed as narcotic3 analgesics4; they are strongly hypnotic5, narcotic and habit forming.

Codeine and its salts are narcotic analgesic and antitussives6. Codeine is less toxic and less habit forming than morphine. Papaverine has a benzylisoquinoline structure, it is a smooth muscle relaxant.

                                                            1 A substance such as sweat or a cellular waste product that is exuded from a cell or organ 2 Plant sap: a milky white liquid produced by some plants such as the rubber tree, whose sap is used to make rubber 3 Causing sleep: able to induce drowsiness, sleep, or stupor, or alter mental states through its chemical properties 4 Pain‐relieving: describes a type of medication that alleviates pain without loss of consciousness 5 Producing sleep or hypnosis 6 prevents or reduces coughing 

Opium Poppy 

Page 14: SIUST Alkaloids and Antibiotics

13  

2- Ipecacuanha or Ipecac : is the dried roots and rhizomes of Cephaelis ipecacuanha family Rubiaceae. Ipecac in the form syrup is used in certain poisonings. It produces emesis1 through a local irritation effect on the GIT mucosa2 and a central medullary3 effect.

The drug contains the principal isoquinoline alkaloid called Emetine. Ipecac is used as an expectorant and emetic and in the treatment of amoebic4 dysentery5, emetine hydrochloride (salt) is given by injection (not orally) because it produces nausea6 and vomiting.

Indole Alkaloids

This group includes a number of alkaloids which posses an indole ring as part of its structure. The important drug and their alkaloids of the indole group are the following:

1- Rauwolfia ( or Rauvolfia ) :is the dried roots and rhizomes of Rauwolfia serpentina

F. Apocynaceae. The drug contains Reserpine as the major indole alkaloid. Reserpine is used in hypertension, as sedative7 and tranquilizing8 agent.

                                                            1 Vomiting 2 Membrane which secretes mucus 3 Of the marrow 4 Pus‐filled cavity usually in the liver, caused by infection from an amoeba, Entamoeba histolytica. 5 intestinal disease 6The unsettling feeling in the stomach that accompanies the urge to vomit.  7 drug which causes calmness and relaxation, drug that reduces tension and anxiety 8 calm down 

 

Page 15: SIUST Alkaloids and Antibiotics

14  

Calabar bean 

 Calabar bean seed

Physostigmine

2- Catharanthus or vinca : is the dried whole plant of Catharanthus roseus, F. Apocynaceae, formerly designated Vinca rosea .

Catharanthus contains many alkaloids, but the most important and medicinally useful alkaloids of this group are: Vinblastine and Vincristine. The catharanthus alkaloids belong to a class of Bisindole derivatives (dimeric indole ) with antineoplastic1 activity. Vinblastine is used for the treatment of Hodgkin's disease2 , and lymphocytic lymphoma (non-Hodgkin's lymphomas). Vincristin is used in the treatment of acute lymphocytic leukemia in children, small cell lung cancer…..etc.

3- Calabar bean or physostigma: Calabar beans are the dried ripe

seeds of Physostigma venenosum F. Fabaceae ( leguminosae ). Calabar beans contain several alkaloids, the major is Physostigmine or Eserine. Physostigmine is employed in ophthalmology as miotic3 agent for the treatment of glaucoma4. glaucoma4.

4- Ergot or rye ergot: is the dried sclerotium5 of a fungus called

Clavicips purpurea F. Clavicipitaceae. Erogt contains a large a number of alkaloids, the most important of which are 1- water-soluble group, represented by Ergometrine alkaloids. 2- water-isoluble group, represented by ergotamine alkaloids. The medicinally useful alkaloids are all derivatives of Lysergic6 acid, Ergometrine (or Ergonovine ) is used as oxytocic7 drug to assist delivery in labour (incresase uterine contraction ), and to reduce post-partum8 bleeding. Ergotamine is employed as analgesic for the treatment of migraine9 headache (cerebral vasoconstrictor).

                                                            1 Controlling cancer: preventing or inhibiting the growth of cancers  2 Tumor of lymph nodes: a malignant form of lymphoma marked by progressive enlargement of the lymph nodes and spleen and sometimes of the liver 3 Having small pupils of the eye 4 Disease of the eye characterized by increased fluid pressure within the eye (causes impairment or loss of vision) 5 Resting state of a plasmodium, vegetative form of some fungi 6 Acid produced from fungus: a crystalline acid, soluble in most organic solvents. Source: ergot fungus. 7 Inducing or speeding up childbirth by causing contractions in the muscles of the uterus 8 After birth 9 Extremely bad headache: a recurrent, throbbing, very painful headache, often affecting one side of the head and sometimes accompanied by vomiting or by distinct warning signs, including visual disturbances 

Page 16: SIUST Alkaloids and Antibiotics

15  

Page 17: SIUST Alkaloids and Antibiotics

16  

Imidazole Alkaloids The most important pharmaceutical drug of this group is Pilocarpine alkaloid from Pilocarpus. Found in:

1- Jaborandi or Pilocarpus: Consists of the leaflets of Pilocarpus jaborandi and other species of Pilocarpus, F.Rutaceae. The medicinally useful alkaloid of jaborandi is Pilocarpine and its salts (hydrochloride) are used in:

- In ophthalmic practice as they cause contraction of the pupil of the eye. - The action is antagonistic to that of atropine.

Alkaloidal Amines (Protoalkaloids) The alkaloids in this group do not have nitrogen as part of the heterocyclic ring system. The drugs containing alkaloidal amines are:

1- Ephedra:  is the entire plant or the overground portion of Ephedra sinica or other species of ephedra, Family Ephedraceae, Ephedra is a source of the alkaloids Ephedrine and Pseudoephedrine. Ephedrine relaxes the bronchial smooth muscle, i.e. used for the relief of asthma1 and hay fever2. In large doses, Ephedrine may cause hypertension, headache, vomiting, palpitations3, nervousness and insomnia. Pseudoephedrine is used as decongestant4 in common cold.

                                                            1 Respiratory disease: a disease of the respiratory system, sometimes caused by allergies, with symptoms including coughing, sudden difficulty in breathing, and a tight feeling in the chest. 2 Allergy to some kinds of pollen that appear in the springtime.  3 An irregular or unusually rapid beating of the heart, either because of a medical condition or because of exertion, fear, or anxiety. 4Respiratory drug: an agent that relieves nasal congestion. 

        

Page 18: SIUST Alkaloids and Antibiotics

17  

2- Colchicum: consists of the dried seed and corm of Colchicum autumnale F.Liliaceae.

The drug contains Colchicine alkaloid which has one amido1 nitrogen atom. Colchicine and Colchicum preparations are used to relieve gout2, but must be used with caution. The alkaloid is also employed in biological experiments to produce multiplication of the chromosomes in a cell nucleus (i.e. causes mutation).

3- Khat (or ghat) or Abyssinian tea: Consists of the fresh leaves of Catha edulis F.Celastraceae. The young, fresh leaves that come from the tips of the branches contain the optimum amount of the alkaloidal amine called: Cathinone. Cathinone is potent phenylalkylamine alkaloid which has pharmacological properties similar to those of Amphetamine3. The leaves of Khat are chewed habitually to alleviate the sensation of hunger and fatigue, to attain a state of euphoria4 and stimulation. In older leaves, the active compound Cathinone is converted to weakly active compounds Norpseudoephedrine5, and Norephedrine. This conversion also occurs rapidly during the drying of young leaves.

                                                            1 Prefix means amide group(R‐CO‐NH‐). 2 A metabolic disorder mainly affecting men in which excess uric acid is produced and deposited in the joints, causing painful swelling, especially in the toes and feet. 3 Stimulant drug (CNS): a drug formerly used to treat depression and as an appetite suppressant, or any of its derivatives. Technical name amfetamine. 4 Extreme happiness: a feeling of great joy, excitement, or well‐being. 5 CNS stimulant. 

Page 19: SIUST Alkaloids and Antibiotics

18  

Steroidal alkaloids Steroidal alkaloids arise by the inclusion of a basic nitrogen at some point in the steroidal molecule. Many plants of the solanum species accumulate steroidal alkaloids based on a C 27, example: Solasodine, Solanidine and Tomatidine. These are nitrogen analogues of steroidal saponins. Solanidine is found in potatoes (Solanum tuberosum ) F.Solanaceae, as glycoside called Solanine. Tomatidine is found in tomato (Lycopersicon escuiente F.solanaceae ) as glycoside called tomatine. These steroidal gluco alkaloids have surface activity and haemolytic properties as do the saponins (They are also toxic). Plants rich in this group of alkaloids could also be employed for commercial production of steroidal sex hormones.

The glycosides derivatives of the steroidal alkaloids give positive tests with Mayer's and Dragendorff's reagent, but negative results with Fehling's solution. On hydrolysis, they give positive Fehling's test (the liberated glucose sugar reduce Fehling's reagent with the formation of red ppt.). Several plants in the Liliaceae family, notably the genus Veratrum, also contain steroidal alkaloids. Some species of Veratrum, namely, Veratrum californicum contains toxic steroidal alkaloids which are responsible for severe teratogenic 1effects. Animals grazing on V.californicum and other species of Veratrum can give birth to young with a single eye in the centre of the forehead. Other Veratrum alkaloids, especially those found in Veratrum album and Veratrum viride have been employed medicinally as hypotensive2 drugs, and used in the same way as Rauwolfia alkaloids. These drugs contain steroidal alkaloids, example Protoveratrine A and Protoveratine B which are esters of Protoverine.

                                                            1 Agent affecting embryo or fetus: an agent that interrupts or alters the normal development of a fetus, with results that are evident at birth, e.g. a chemical, virus, or ionizing radiation. 2 Causing low blood pressure. 

Seed tuber with sprouts 

Early Rose variety 

Page 20: SIUST Alkaloids and Antibiotics

19  

Purine Alkaloids (or Purine bases) The Purines are derivatives of a heterocyclic nucleus consisting of a 6-membered Pyrimidine ring fused to the 5-membered imidazole ring. The pharmaceutically important bases of this group are all derivatives of 2,6-dioxypurine ( Xanthine).

Drugs containing Purine alkaloids:

1- Coffee beans or coffee seeds: Are the dried ripe seeds of Coffea arabica and other species of coffea F.Rubiaceae.

Coffee seeds a contain 1-2% caffeine and traces of Theophylline and Theobromine. - Caffeine is the major CNS stimulant and has weak diuretic action. - Theobromine has little stimulant action, but has more diuretic activity and muscle relaxant properties. - Theophylline also has low stimulant action and is an effective diuretic, but it relaxes smooth muscle better than caffeine or Theobromine. Medicinally: Caffeine is used as a CNS stimulant. Theobromine is of value as a diuretic and smooth muscle relaxant. Theophylline is an important smooth muscle relaxant for relief of bronchospasm1.

                                                            1 Spasmodic contraction of the bronchi. 

Coffea arabica in fruit – Brazil 

Unroasted coffee(Coffea arabica) 

beans ‐ Brazil

Page 21: SIUST Alkaloids and Antibiotics

20  

Camellia sinensis foliage 

Seed bearing fruit of Camellia sinensis 

       Delphinium Aconitum variegatum

2- Tea: Consists of the prepared leaves and leaf buds of Camellia sinensis (thea sinensis) F.Theaceae.

Green tea: prepared by rapidly drying the freshly picked leaves in copper pans over a mild artificial heat.

Black tea: the leaves are allowed to ferment allowing enzymic oxidation of the polyphenol, and then dried artificially with heat. Tea contains 1-4% Caffeine and small amounts of both theophylline and theobromine.

3- Cocoa or Cocoa beans or Cacao: Consists of the dried ripe seeds of Theobroma cacao F.Sterculiaceae. Cocoa seeds contain 35-50% of oil called cocoa butter or Theobroma oil, 1-4% Theobromine, and 0.2-0.5% Caffeine. Theobroma oil or cocoa butter is used in pharmacy as a suppository base.

Terpenoid Alkaloids The most important example of Terpenoid alkaloids are those found in Aconitum species and species of Delphinium family Ranunculaceae. Plants of the two genera are highly toxic due to the terpenoid alkaloids. Accinte in particular is regarded as extremely toxic due to the presence of Aconitine alkaloid. Species of Delphinium contain alkaloids which are less toxic than Aconitine. Aconites are species of Aconitum which are ornamental herbaceous plants grown for their showy blue or purple flowers. The alkaloid content (Aconitine) is mainly in the roots, makes them one of the most toxic plants. All species of Aconitum and Delphinium are potentially toxic to man and animals

Page 22: SIUST Alkaloids and Antibiotics

21  

1-Concentrate 2-Add 5% HCl 3-Add CHCl3

1-5%NH4OH 2-CHCl3

5%NaOH

1-Acidity 2- CHCl3

General Scheme of Extraction: Powdered Plant Material

The scheme shows that if the plant material consists of seeds or other parts rich in lipids, it is advisable to extract the material at room temperature by maceration with hexane or petroleum ether to give Extract (1) (oil) before proceeding, otherwise, one can start directly from the next step which is maceration or percolation of the dried ground plant material with ethanol 95% (or 90% ) until the material is exhausted. Concentration of the filtered ethanol give Extract (2). Purification of extract (2) can be achieved by partitioning between 5% HCl and CHCl3 to produce Extract(3) (the CHCL3 layer contains neutral and acid substances ), And Extract (4) (the aqueous acid layer contain alkaloidal salt, and other water soluble substance ). Extract(4) is made alkaline (PH=10) with 5%NH4OH and extracted with CHCl3 to produce Extract(5) (the aqueous basic layer contains the quaternary alkaloids and any water soluble materials ). Extract (6) (theCHCl3 layer contains other alkaloids). Extract (6) is then extracted with 5%NaOH solution to give Extract (7) (the CHCl3 layer contains the tertiary alkaloids) and Extract(8) (the aqueous basic layer contains phenolic alkaloids as soluble sodium salts ). Extract (8) is acidified and extracted with CHCl3to produce Extract(9) (the CHCl3 Layer contains the phenolic alkaloids).

Hexane or petroleum ether (maceration)

Ethanol (heat)

Extract (6) CHCl3 layer: contains other alkaloids

Extract (5) Aqueous basic layer: contains quaternary alkaloids

Extract (7) CHCl3 layer: contains tertiary alkaloids.

Extract (8) aqueous basic layer: contains phenolic alkaloids as sodium phenolate salt

(9)CHCl3 layer: contains phenolic alkaloid

Extract (4) Aqueous acid layer: contains alkaloid salts and water soluble substances

Extract (3) CHCl3 layer: contains neutral & acid substances

Exhausted plant material Extract (2)

Defatted plant material Extract (1) oil