z` PHARMACOGNOSY OF ALKALOIDS – GPAT DISCUSSION CENTER

  • PHARMACOGNOSY OF ALKALOIDS

    • March 9, 2018
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    PHARMACOGNOSY OF ALKALOIDS

    Alkaloids are basic nitrogen containing compounds obtained from plants, animals & microorganisms having a marked physiological action

    ?They answer the following chemical tests:

    ? Mayer’s reagent- (potassium mercuric iodide)——cream coloured precipitate

    ?Wagner’s reagent- (iodine in potassium iodide)——-reddish brown precipitate

    ?Hager’s reagent- (salt solution of picric acid)———–yellow precipitate

    ?Dragendorf’s reagent- (potassium bismuth iodide)———reddish brown precipitate

    ?Caffeine is a pseudo alkaloid drug which does not answer this test.

    TYPES OF ALKALOIDS

    ?TRUE ALKALOIDS

    1. Pyrrole & pyrrolidine eg- coca
    2. Pyridine & piperidine eg- coniine
    3. Tropane eg- atropine
    4. Quinoline eg- cinchona
    5. Indole eg- rauwolfia
    6. Purine eg- caffeine
    7. Steroidal eg- kurchi
    8. Isoquinoline eg- opium

    ? PROTO ALKALOIDS

           eg- ephedrine

    ? PSEUDO ALKALOIDS

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    INDOLE ALKALOIDS

    ?ERGOT / ARGOT / ST. ANTHONY’S FIRE

    ?BIOLOGICAL SOURCE: schlerotium of fungus claviceps purpurea, at the ovary of rye plant secale cereale

    Family: graminae (fungus belongs to family clavicipitaceae)

    ?Chemistry: Derivatives of lysergic acid. Water soluble ones are ergometrine & ergometrinine

    Water insoluble ones are ergotamine & ergotoxine. Only the levo isomer is active

    ?Uses: Ergometrine is an oxytocic drug but its methyl derivative is preferred as it causes less hypertension. Ergotamine is analgesic in migraine

    ?Chemical Test:

    1⃣ Gives a blue colour with Van Curk’s reagent (para dimethyl amino benzaldehyde)

    2⃣ Gives blue fluorescence in water

    ?VINCA / PERIWINKLE

    ?BIOLOGICAL SOURCE: aerial parts of catharanthus roseus

    Family: apocynaceae

    ?Chemistry: Indole alkaloids such as vinblastine, vincristine, ajamlicine & serpentine

    ?Use: Potent anti cancer agent, hypotensive & anti diabetic

    ?NUXVOMICA

    ?BIOLOGICAL SOURCE: dried seeds of strychnos nuxvomica

    ?Family: loganiaceae

    ?Chemistry: Contains two main indole alkaloids strychnine & brucine

    ?Use: Rarely used as a nerve tonic as it is poisonous in large doses

    ?Chemical Test:

    1⃣. Section when treated with concentrated HNO3 shows a yellow colour with brucine

    2⃣ Section when treated with ammonium vanadate & H2SO4 shows a purple colour with strychnine

    3⃣ Strychnine when treated with H2SO4 & K2Cr2O7 develops a violet to yellow colour

    ?RAUWOLFIA / SARPAGANDHA

    ?BIOLOGICAL SOURCE: dried roots of rauwolfia serpentina

    ?Family: apocynaceae

    ?Chemistry: Reserpine, ajamlicine, serpentine

    ?Use: Antihypertensive by preventing uptake of adrenaline

    ?Chemical Test:

    1⃣Freshly fractured surface of the root when treated with concentrated HNO3 shows red coloured medullary rays

    2⃣Reserpine gives a violet colour with vanillin in acetic acid

    ?TROPANE ALKALOIDS

    ?BELLADONA

    ?BIOLOGICAL SOURCE: dried leaves of atropa belladonna

    ?Family: solanaceae

    ?Chemistry: Atropine, hyoscyanine, belladonine

    ?Use: Atropine is a parasympatholytic, thus decreases secretion & spasms

    ?Chemical Test:

    1⃣Vitali morin test – to the drug fuming nitric acid is added & it is evaporated to dryness.

    2⃣Methanolic KOH is added to the acetone solution of the nitrated residue. It develops a violet colour

    ?STRAMONIUM

    ?BIOLOGICAL SOURCE: dried leaves & flowering tops of datura stramonium

    Family: solanaceae

    ?Microscopic Characters:

    Dorsiventral leaf Collenchyma above & below the mid rib

    Unicellular covering & glandular trichomes Xylem surrounded by phloem Anisocytic stomata

    ?Chemistry: Hyoscine, atropine, belladonine

    ?Use: Hyoscine is an anti emetic

    ?Chemical Test: Vitali morin test

    ?COCA LEAVES

    ?BIOLOGICAL SOURCE: dried leaves of erythroxylon coca (bolivian variety) Erythroxylon truxillense (Peruvian variety)

    Family: erythroxylaceae

    ?Microscopic Characters:

    Dorsiventral leaf. Collenchyma above & below mid rib. Xylem surrounded by phloem & pericyclic fibres. Paracytic stomata

    ?Chemistry: Cocaine, cinnamoyl cocaine, tropocaine, benzoylecgonine

    ?Use: Local anaesthetic

    ?Chemical Test: Drug powder when heated with concentrated H2SO4 gives a typical odour of methyl benzoate

    ?QUINAZOLINE ALKALOIDS

    ?VASAKA LEAF / ADULSA

    ?BIOLOGICAL SOURCE: dried & fresh leaves of adhatoda vasica

    Family: acanthaceae

    ?Chemistry: Vasicine, vasicinone & adhatodic acid

    ?Uses: Vasicine is an expectorant. It gets oxidized to vasicinone which in an abortifacient in large doses, otherwise a bronchodilator

    ?PYRIDINE ALKALOIDS

    ?LOBELIA HERB / INDIAN TOBACCO / ASTHMA WEED

    ?BIOLOGICAL SOURCE: dried aerial parts of lobelia nicotianefolia

    Family: Campanulaceae

    ?Chemistry: Lobeline, lobelidine & isolobanine

    ?Use: Respiratory stimulant

    ?Chemical Test:

    1⃣ lobeline solution if heated gives typical odour of acetophenone

    2⃣ lobeline in H2SO4 when treated with formaldehyde develops red colour

    ?IMIDAZOLE ALKALOIDS

    ?PILOCARPUS

    ?BIOLOGICAL SOURCE: dried leaves of pilocarpus jaborandi Pilocarpus microphyllus

    Family: rutaceae

    ?Chemistry: Contains pilocarpine, pseudopilocarpine, pilosine & limonene

    ?Uses: Antagonist to atropine, causes miosis, increases salivation & sweating

    ?INDOLE ALKALOIDS

    ?CALABAR BEANS

    ?BIOLOGICAL SOURCE: dried type seeds of physostigma venenosum

    Family: leguminosae

    GEOGRAPHICAL SOURCE: Africa

    ?Chemistry: Contains physostigmine, starch & proteins

    ?Use: Helps in contraction of pupil, retards respiration & causes bradycardia

    ?OPIUM / POPPY PLANT

    ?BIOLOGICAL SOURCE: dried latex obtained from capsules of papaver somniferum

    Family: papaveraceae

    ?Chemistry: Contains phenanthrene type of alkaloids such as morphine & codeine & benzyl isoquinoline type of alkaloids such as papaverine & noscapine. These occur as salts of meconic acid

    ?Use: Morphine is a narcotic analgesic & stimulant. Codeine is an anti tussive. Papverine is a smooth muscle relaxant

    ?CINCHONA BARK / JESUIT’S BARK / PERUVIAN BARK

    ?BIOLOGICAL SOURCE: dried bark of cultivated trees of cinchona calisaya ,Cinchona officinalis, Cinchona ledgeriana, Cinchona succirubra

    Family: rubiaceae

    ?Microscopic Characters: Cork cells are thin walled. Cortex has phloem fibres. Medullary rays with radially arranged cells. Idioblast of calcium oxalate is a specific characteristic. Starch grains in parenchymatous tissues

    Stone cells rarely present

    ?Chemistry: Contains quinine, quinidine, cinchonine & cinchonidine. Also contains quinic acid & cinchotannic acid

    ?Chemical Test:

    1⃣n heating the drug in a dry test tube with glacial acetic acid, purple vapours are produced

    2⃣ Thalleoquin test: drug + bromine water + dilute ammonia gives an emerald green colour

    3⃣Drug when treated with quinidine solution gives a white precipitate with silver nitrate which is soluble in nitric acid

    ?Uses: Anti malarial, anti pyretic, quinine is used in arrythmias against atrial fibrillation

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    ?ISOQUINOLINE ALKALOIDS

    ?IPECAC

    ?BIOLOGICAL SOURCE: dried roots of cephalis ipecacuanha (brazilian / rio) Cephalis acuminata (panama / cartagena)

    Family: rubiaceae

    ?Chemistry: Brazilian – emetine:cephalin ratio is 4:1

    Panama – emetine:cephalin ratio is 1:1

    ?Uses: Expectorant in mild doses & as an emetic in large doses

    Emetine also possesses anti protozoal activity

    ?PYRIDINE- PIPERIDINE ALKALOIDS

    ?TOBACCO

    ?BIOLOGICAL SOURCE: dried leaves of nicotiana tabacum

    Family: solanaceae

    ?Chemistry: Nicotine, nornicotine & anabasine

    ?Use: Stimulant

    ?STEROIDAL ALKALOIDS

    ?KURCHI

    ?BIOLOGICAL SOURCE: dried bark of holarrhena antidysenterica

    Family: apocynaceae

    ?Chemistry: Steroidal alkaloid conessine & norconessine

    ?Use: Amoebic dysentery

    ?ASHWAGANDHA

    ?BIOLOGICAL SOURCE: dried roots of withania somnifera

    Family: solanaceae

    ?Chemistry:

    2 types of chemical constituents

    1⃣ steroidal lactones called withanolides like withaferine

    2⃣ alkaloids like withanine, somniferine, anaferine. Also contains alcohols known as somnitol & somnirol

    ?Uses:

    Sedative, hypnotic, hypotensive & immunomodulatory

    ?PYRAZOLINE ALKALOIDS

    ?PEPPER

    ?BIOLOGICAL SOURCE: dried fruits of piper nigrum

    Family: piperaceae

    ?Chemistry: Alkaloid piperine is responsible for pungent taste aong with piperetine, resins, volatile oils containing limonene & pinen responsible for the odour

    ?Uses: Bronchitis & gonorrhoea

    ?PROTO ALKALOIDS

    ?EPHEDRA / MA HUANG

    ?BIOLOGICAL SOURCE: dried stem of ephedra gerardiana

    Family: ephedreaceae / gnetaceae

    ?Chemistry: Contains amino alkaloids like ephedrine, norephedrine & pseudo ephedrine

    Uses: Sympathomimetic & bronchodilator

    ?COLCHICUM / AUTUMN CROCUS

    ?BIOLOGICAL SOURCE: dried seeds & corms of colchicum luteum. Family: liliaceae

    ?Chemistry: Contains amino alkaloid colchicine & demecolchicine

    ?Uses: Rheumatism, treatment of gout, anti tumour activity & polyploidy

    ?ACONITE / BACHNAG

    ?BIOLOGICAL SOURCE: dried roots of aconitum napellus

    Family: ranunculaceae

    ?Chemistry: Diterpene alkaloids such as aconitine, neopelline, neoline & small amount of ephedrine. Aconitine is an active constituent but if hydrolysed forms benzoyl aconine & aconine which are less active

    ?Uses: Externally in neuralgia & sciatica

    ?PSEUDO ALKALOIDS

    ?COFFEE

    ?BIOLOGICAL SOURCE: dried seeds of coffee Arabica

    Family: rubiaceae

    ?Chemistry: Contains caffeine which is a salt of chlorogenic acid, volatile oil known as caffeol, enzymes & other phenolic compounds

    ?Uses: Stimulant, diuretic (due to theophylline), & source of caffeine

    ?Chemical Test:

    1⃣ Murexide test: caffeine when heated with HCl & potassium chlorate gives a residue which turns purple when exposed to ammonia vapours

    2⃣ Caffeine forms a white precipitate with tannin solution

    ?TEA

    ?BIOLOGICAL SOURCE: prepared leaves of thea sinensis

    Family: theaceae

    ?Chemistry: Contains caffeine, theophylline, theobromine, oxidase enzyme & tannins

    ?Use: Stimulant, diuretic, source of caffeine

    ?Chemical Test: Murexide test

    ?KOLA NUTS / BISSY SEEDS

    ?BIOLOGICAL SOURCE: seeds of cola nitida

    Family: sterculiaceae

    ?Chemistry: Contains caffeine, theobromine & a red pigment known as kola catechin

    ?Use: Stimulant

    ?COCOA SEEDS

    ?BIOLOGICAL SOURCE: seeds of theobroma cacao

    Family: sterculiaceae

    ?Chemistry: Caffeine. Theobromine, other phenolic compounds

    ?Use: Stimulant

     

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