phg 322 pharmacogonsy ii lecture 1 presented by assistant prof dr ebtesam alsheddi n.
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PHG 322 Pharmacogonsy II lecture 1 Presented by Assistant Prof. Dr. Ebtesam Alsheddi. بسم الله الرحمن الرحيم. Office: second flour # 84 Email: ebtesam.saad@yahoo.com Site: faculty.ksu.edu.sa/10252. Topics to be covered: (cont.).

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phg 322 pharmacogonsy ii lecture 1 presented by assistant prof dr ebtesam alsheddi

PHG 322Pharmacogonsy IIlecture 1Presented byAssistant Prof. Dr. EbtesamAlsheddi

بسم الله الرحمن الرحيم

slide2

Office: second flour # 84

  • Email: ebtesam.saad@yahoo.com
  • Site: faculty.ksu.edu.sa/10252
slide3

Topics to be covered: (cont.)

  • 1) Plants containing Alkaloids (botanical and chemical characters):
    • Introduction
    • Phenylalkylamine, Tropolone and Imidazole alkaloids
    • Pyridine and piperidine alkaloids
    • Tropane alkaloids
    • Quinoline and isoquinoline alkaloids
    • Opium alkaloids
    • Indole alkaloids
    • Carboline, purine, steroidal and terpenoidal alkaloids
slide4

Topics to be covered:

  • 2) Marine derived drugs:
    • Biomedical potential of marine natural products
    • Microalgae as a drug source
    • Biologically active substances from marine sponges
slide5

Topics to be covered:

  • 3) Plants containing Glycosides (botanical and chemical characters):
    • Introduction
    • Phenolic, cyanogenic and thioglycosides
    • Coumarins, flavonoidal glycosides and related compounds
    • Anthracene derivatives
    • Cardiac glycosides
    • Saponins
slide6

Topics to be covered:

  • 4) Toxicological Pharmacognosy:
    • Poisonous plants
    • Plants as drugs of abuse
    • Hepatotoxic plants
    • Toxic mushrooms
    • 3) Herb-drug interactions
slide9

Alkaloids

  • Definition
  • Alkaloids, which mean alkali-like substances, are basic nitrogenous compounds of plant or animal origin and generally possessing a marked physiological action on man or animals.
  • The nitrogen is usually contained in a heterocyclic ring system.

Deviation from Definition

Some alkaloids are not basic e.g. Colchicine, Piperine,

Few alkaloids contain nitrogen in a non-ring system

e.g. Ephedrine, Colchicine. Mescaline

3) Plant origin:

Some alkaloids are derived from bacteria, fungi, insects, frogs, animals.

slide10

Function of alkaloids in plants

1) Protective function against insects or herbivores

2) They are end products (detoxification)

3) Source for energy and reserve of nitrogen

distribution in plant
Distribution in Plant:
  • All Parts e.g. Datura.
  • Barks e.g. Cinchona
  • Seeds e.g. Nux vomica
  • Roots e.g. Aconite
  • Fruits e.g. Black pepper
  • Leaves e.g. Tobacco
  • Latex e.g. Opium
slide12

Nomenclature

  • Alkaloids terminate with the suffix: (ine)
  • Their names may be derived from:
  • Genusname e.g. Atropine from Atropa
  • Speciesname e.g. Cocaine from Coca
  • Commonname e.g. Ergotamine from Ergot
  • Physiologicalactivity e.g. Emetine (emetic)
  • Discoverere.g. Pelletierine from Pelletier
slide13

Prefixes and suffixes

These are, usually,addedto the name of theparentalkaloid and are used to designaterelatedalkaloids, generally present in thesameplant.

Examples are:

I. Prefixes

  • Nor-: designatesN-demethylation or N-demethoxylatione.g.Nornicotine
  • Apo-: designatesdehydratione.g. Apomorphine
  • Iso-,Pseudo-,Neo-andEpi-indicate different types of isomers
slide14

II. Suffixes

1) –dine:designates isomerism as in case of the Cinchonaalkaloidsquinine (l)& quinidine (d)

cinchonidine (l)& cinchonine (d)

2) –ine:indicates, in case of ergot alkaloids, a lower pharmacological activity e.g. ergotaminineis less potent than ergotamine

slide15

Most alkaloids colourless

-colchicine & berberineyellow

- canadineorange

Physical properties:

1) Condition:

  • Most alkaloids arecrystalline solids
  • Some are liquids

non-volatile

volatile

e.g. pilocarpine and hyoscine

e.g. nicotine and coniine

2) Colour:

  • Some are coloured:
slide16

3) Solubility:

  • Solubility of alkaloids & their salts is importantbecause:

a) They are often administered in solution

b) Differencesin solubility between alkaloids& their

saltsis used for:

- isolation of alkaloids

-purificationfromnon-alkaloidalsubstances

slide17

Solvent

Alkaloidal bases

Alkaloidal salts

Soluble

Alcohol

Soluble

Soluble

except:

Insoluble

except:

Organic

solvents

-morphine&psychotrine

→insol. in ether

- lobeline hydrochloride

→ CHCl3(soluble)

-theobromine&

theophylline

→ benzene (insol.)

except:

Insoluble

Soluble

except:

H2O

quinine sulphate

→insoluble in H2O

- caffeine

- ephedrine

-codeine

- colchicine

- pilocarpine

- quat. ammoniumbases

slide18

4) Optical activity:

  • Many alkaloids are optically active due to ?

→ presence of one or more asymmetric carbon atom(s)

  • Optically active isomers may show different physiological activities.
  • l-ephedrineis 3.5 times more active than d-ephedrine.
  • l-ergotamineis 3-4 times more active than d-ergotamine.
  • d- Tubocurarineis more active than the corresponding l- form.
  • Quinine (l-form) is antimalarial and its d- isomer quinidine is antiarrythmic.
  • The racemic (optically inactive) dl-atropine is physiologically active.
slide19

nicotine

coniine

Chemical properties:

  • Alkaloids contain:C, H, N
  • Most of them contain oxygen
  • Fewalkaloids are oxygen free
chemical properties
Chemical Properties:

I- Nitrogen:

  • Primary amines R-NH2 e.g. Norephedrine
  • Secondary amines R2-NH e.g. Ephedrine
  • Tertiary amines R3-N e.g. Atropine
  • Quaternary ammonium salts R4-N e.gd-Tubocurarine

II- Basicity:

  • R2-NH > R-NH2 > R3-N
  • Saturated hexacyclic amines is more basic than aromatic amines.
slide21

1) Nitrogen in alkaloids

Basicity

Number of

nitrogen atoms

Type of amino

group

1) Number of nitrogen atoms:

  • Usually one N atom
  • Some contain more than one

→ up to 5 N atoms

e.g. nicotine → two

ergotamine→five

21

slide22

2) Type of amino group:

  • N in alkaloids → in form of amine

Primaryamino group

Secondaryamino group

Tertiaryamino group

Quaternaryammonium ion

e.g.

Norpseudo-ephedrine

Ephedrine

Nicotine

Tubocurarine

slide23

]

[

Alkaloid

[

]

3) Basicity:

  • A lone pair of electronsonN atom→ basic character

→alkaloidsresembleNH3in chemical characters

→formsaltswithacidswithout liberation of H2O

+H+Cl-

Alkaloid hydrochloride

23

Present as:

slide24

Pyridine

Piperidine

increase basicity

decrease basicity

unsaturationdecreases basicity

Factors influencing the degree of basicity:

Structure of the molecule

Presence & position of other substituents & fuctional groups

e.g. degree of unsaturation

of heterocyclic ring

Electron

releasing groups

Electron

withdrawing gps

e.g.

carbonyl group

e.g.

alkyl group

Piperidinealkaloids →

morebasicthanpyridinealkaloids

slide25

Narceine

→ Alkaloids may be:

  • Neutral (not basic)

Ricinine

→electronavailabilityon

nitrogen atomdecreases

  • Amphoteric

→due to the presence of acidic group(s)

e.g. phenolicalkaloids

e.g.alkaloids containing

carboxylic group

Morphine