Chemistry of alkaloid

NORSYA

MIMI BT CHE

SULAMAN

(153504)

NUR

FATIHAH BT ABAS (154120)

NURUL

FADZILLAH BT MOHD

HATA (152266)

NOR HIDAYAT

BT YUSOF

(152356)

G4

INTRODUCTION

• Alkaloid~ an example of secondary metabolites• Naturally occurring organic compounds

containing nitrogen moiety, and are usually heterocyclic in nature.

• Contains nitrogen ~ usually derived from an amino acid.

• Normally have a significant physiological action on humans and animals.

CHARACTERISTICS OF ALKALOIDS

• Basic in nature due to the presence of nitrogen in their ring

• Mostly obtained from plant materials.• Have bitter tasting.• Give a precipitate with heavy metal

iodides• Have high pharmacological and

physiological activities.

Quinine •an antipyretic alkaloid•Functional groups present in quinine are: methoxy –OCH3, hydroxyl –OH, tertiary amine group, and etc

Cocaine •obtained from coca leaves.•highly narcotic.•stimulates the central nervous system i.e. CNS depressant.•can lead to psychiatric problem when taken in high dose or when addicted to it.

Caffeine •obtained from tea leaves.•also a strong stimulant which can increases alertness, thereby causing insomnia when the body gets addicted.

EXAMPLES

Tests for Alkaloids

• picric acid• Observation :

yellow precipitate

• mercuric potassium iodide solution

• Observation: white precipitate

• potassium bismuth iodide solution

• Observation : orange coloured precipitate

• iodine in potassium iodide

• Observation : red-brown precipitate

HAGERS REAGENT

MAYER ‘S REAGENT

DRAGENDORFF'S

REAGENT WAGNER’S REAGENT

Occurrence of Alkaloids• Occur in bacteria (Pseudomonas aeruginosa) and rarely

in fungi (pscilocin from hallucinogenic mushrooms).• Some alkaloids occur in several genera from different

species (caffeine), but most occur in closely related species.

• Some occur in certain families (hyoscyamine), while others occur only in a specific species (morphine).

• Rarely do plants contain more than 1 type of alkaloid. • All alkaloids of one plant will have a common

biogenenetic origin

• Alkaloids occur in all plant parts, but are usually localized in one organ (e.g. the bark or seeds).

• Within the plant, [alkaloid] can vary widely from part to part – some parts may contain no alkaloids.

• Occasionally, different alkaloids also form in different parts of the plant.

• Alkaloid concentrations occur in wide ranges – e.g. Madagascan periwinkle contains 3g per (anti-cancer) alkaloids per tonne of leaves.

Classification of alkaloids Alkaloids have a large variety in their botanical & biochemical

origin, in chemical structure and pharmaceutical action. Therefore, like flavonoids, a range of different classification systems exist for grouping alkaloids.

They can therefore be classified according to their• Biological origin• Chemical structure - 2 divisions

• i. Atypical/non-heterocyclic alkaloids (protoalkaloids or biological amines)

• ii. Typical/heterocyclic alkaloids (divided into 14 groups according to their ring structure)

• Biosynthetic pathway

Classification of alkaloids

• Terpenoid Indole Alkaloids• Benzylisoquinoline Alkaloids• Tropane Alkaloids• Purine Alkaloids• Pyrrolizidine Alkaloids• Other alkaloids: Quinolizine, Steroidal

glycoalkaloids

Terpenoid Indole Alkaloids

• Large group of about 3,000 compounds• Indole moiety provided by Tryptamine (derived

from Tryptophan) and a Terpenoid component • Moneterpenenoid indole alkaloid:• the iridoid glycoside secologanin (derived from

the monoterpene Geraniol) and Tryptamine

Benzylisoquinoline Alkaloids

• A large and diverse class present in a range of plant families.

• The first biosynthetic step is decarboxylation of Tyrosine by Tyrosine Decarboxylase (TYDC) to form Tyramine.

• Coupling of two Tyramine derivatives yields (S)-Norcoclaurine.

• Norcoclaurine is the precursor of several thousand benzylquinoline alkaloids.

Tropane Alkaloids

• Plants containing these alkaloids have been used throughout history as poisons, but many of the alkaloids do have valuable pharmaceutical properties.

• Known to be present in the Solanaceae family• The TA Cocaine was found in very small amounts in

the original Coca-Cola formula, but was not the main concern of the USDA at the time. Caffeine was considered to be the major problem with the drink.

Cocaine

Purine Alkaloids

• Caffeine the most important example in coffee, tea, mate', cacao, camellia.

• Purine alkaloid biosynthesis starts with xanthosine, a nucleotide degradation product.

Pyrrolizidine Alkaloids

• The leading plant toxins.• Over 360 different structures, found in 3% of

the world flowering plants.• Primarily restricted to; Boraginaceae,

Asteraceae, Fabaceae, and Orchidaceae.• Most of them are esters of basic alcohols

known as necine bases.

Alkaloids in modern medicine

Atropine-antidote to nerve gas poisoning Codeine, Morphine -Analgesic

(painkiller)

Alkaloids in modern medicine

Caffeine-central nerve system stimulant

Quinine-anti malarial, facilitated exploration of the tropics

Sanguinarine Antibacterial showing

anti plaque activity, used in toothpastes and oral

rinses

Biosynthesis of morphineMORPHINE •Obtained from the opium poppy Papaver somniferum.• used in medical field for relief the pain since early 1500s.

CODEINE•Occur naturally which simply the methyl ether of morphine and converted to morphine in the body•Used in prescription cough medicines and as analgesic.

HEROIN •Does not occur naturally but synthesized in laboratory by diacetylation of morphine.

Pathway of morphine biosynthesized

DERIVATIVE FROM

(S)-RETICULINE

(S)-Reticuline: the Chemical Cameleon(twisted and turned before being oxidized to generate different structures)