Alkaloids

AlkaloidsDr. AmitrRatn Gangwal

IndoreIndia

(images and structures are taken from internet and not the authors original content or creation)

Plant secondary metabolites

Alkaloid

Dhatura fruit: To Lord Shiva

Celebrities (brat/s)

Rahul MahajanLindsay LohanBritney SpearsJaswant Singh (exception)Paris HiltonFardin Khan

Most of them were convicted in

court on account of using or

possessing cocaine and other

banned drugs.

Few famous/celebrated drugs

obtained from plants are:

• Cocaine

• Atropine

• Papevarine

• Morphine

• Quinine

• Codeine

• Thebaine

• Caffeine

• Reserpine

• Nicotine

• Vincristine and vinblastine etc

Vinca rosea/Sadabahar/Periwinkle

They all are alkaloids and possess important pharmacological actions viz anticancer, hypotensive, relaxants, painkiller etc.

Most of the allopathic drugs used today, trace their roots to plants metabolites in general and to alkaloids in particular.

Jumbo

molecules

Vincristine

Reserpine

Tubocurarine

IntroductionThey are alkali like compound.

Mainly obtained from plants.

Should possess nitrogen atom essentially in the ring (heterocyclic form)

Should be potent.Should respond to classical four

tests meant for their identification.

Distribution:SolanaceaeRubiaceaeLiliaceaeAmaryllidaceae are the few

families, plants of which are rich in alkaloids.

Example of lower plant possessing alkaloids is fungal alkaloid providing ergot which possess a gamut of biological actions.

PropertiesMainly colorless, crystalline solid.

But coniine, sparteine and nicotine are liquid and berberine and betanidine possess colors.

In general alkaloidal salts are soluble in water and their free forms are soluble in organic solvents (mainly ether and chloroform).

Some of the pseudo and proto alkaloids show higher solubility in water e. g. colchicine and caffeine.

They are basic in nature due to the lone pair of electrons on nitrogen.

Their salt formation with an inorganic acid prevents many a time their decomposition.

ExtractionOne has to consider following steps in sequential manner for the extraction of alkaloids:

Separation of the alkaloid from unwanted material(Hardly any plant which contains only one alkaloid exclusively.)

Separation of each individual alkaloid from the mixture using chromatographic techniques.

Extraction depends mainly on: The alkaline nature of most alkaloids

The ability and ease of formation of alkaloidal salt with acids

Relative solubilities of resulting salts either in organic or aqueous media.

Identification testsMayer’s reagentDragendorff’s reagentWagner’s reagentHager’s reagentBut proto and pseudo alkaloids

do not respond to these tests and so they got the names.

Functions in plantsWaste metabolites Waste products or secretary

productsThey play defensive roles in

plants.But their exact role in plants is a

debatable issue.

Nomenclature From the generic nameAtropine from Atropa belladona

From the specific name

Belladonine from A. belladonaFrom common name

Ergotamine from ergot

From their specific pharmacological actions

Narcotine from Papaver somniferum

Morphine from p somniferum.

From the name of discovererPelletierine from the bark of Puniea granatum.

Generally with all the alkaloids suffix ine is added.

Classification They can be classified based on

their:pharmacological actionsbiosynthetic precursors and mostly used chemical structure which we will see in detail:

Pyrorolidine alkaloids: hygrine

Piperizine:lobeline

Tropane: atropine

Quinoline: quinine

Isoquinoline:morphine

Aporphine: boldine

Indole: ergometrinine

Imidazole: pilocarpine

Purine: caffeine

Steroidal: solanidine

BiosynthesisThey are mainly derived from aromatic amino acids in the plants. But again few alkaloids defy this rule.

Some interesting facts about alkaloids

Hemlock alkaloid (Conium maculatum)

Opium poppy

No manipulation in opium alkaloids can be done without the permission of Govt. of India.

Neemuch and Ghazipur: Govt. opium factories.

Alkaloid colony in Neemuch.

Alkaloids pvt. ltd. (Secunderabad, AP)

Individual drugs

Opium

Thank you