alkaloids lab

Alkaloids

Basic nitrogenous compounds with physiological activity

have pharmacological actions

secondary metabolites extracted from plant samples

amine-containing

Amide-containing

Phenolic containing

Classification of alkaloids

basic in nature

pH of amine-containing

neutral

ph of quarternary amine and amide alkaloid

acidic and basic

pH of phenolic alkaloid

Bitter, colorless, crystalline (except CANS)

physical properties of alkaloids

Coniine, Arecoline, Nicotine, Sparteine

Meaning of CANS

Ranunculaceae

Buttercup family

protoalkaloid

Rubiaceae

caffeine family

Papaveraceae

Opium poppy

source of morphine and codeine

Solanaceae

family of atropine and nicotine

Berberidaceae

plants under this usu. contain berberine (has antimicrobe ppts)

Fabaceae

legume family

Liliaceae

many alkaloids under this have medicinal ppts

Ranunculaceae

Rubiaceae

Papaveraceae

Solanaceae

Berberidaceae

Fabaceae

Amaryllidaceae

Liliaceae

Families associated with alkaloids

Free alkaloids

soluble in non polar solvents (like Hexane & DCM)

water insoluble/ sparingly soluble

addition of acid → alkaloidal salt

Remedy for water insolubility of free alkaloids

stats otto process

Process specific to alkaloids

one of the most common method employed

obtains very minimal impurities

Alkali (NH3 or NH4OH)

used to treat defatted and concentrated plant extract to liberate the free alkaloid from their salts and then separated with organic solvents

aqueous acid (HCl or H2SO4)

used to further remove impurities from the organic liquid and convert the alkaloid into a salt (leaving impurities in liq)

NaHCO3 or NH3

Used to precipitate the alkaloidal salt and convert it into free alkaloids (crude) and then separated by filtration or extraction w/ org solvents

Dragendorff’s

Krauts

Aka KBiI

Forms orange ppt

Mayer’s

Aka HgKI

Forms cream ppt

Wagner’s (Bourchadat’s)

most sensitive

Aka I in KI

Forms reddish brown ppt

Valser’s

Aka HgI

Forms White ppt

Marme’s

Aka KCdI

Forms white ppt

Hager’s

Aka Picric acid

Forms yellow ppt

Sonnenchein’s

Aka PMo Acid

Forms blue/green ppt

Scheibler’s

Aka PW acid

Forms characteristic color

Gold Chloride

Forms yellow ppt

5% Tannic acid

Forms buff ppt, insoluble in NH3

Vitali-Morin

Atropine - Purple

Gerrard’s

Atropine - Red

Hyoscyamine - Red after warming

Hyoscine - White ppt

Van-Urks

Ergot alkaloids - Blue

Thalleiquin

Quinine, Quinidine - Purple

Mandelin’s

Strychnine - Violet

Murexide

Caffeine - Pink

Heterocyclic

Typical

N with the ring

Class based on ring

Ex. quinine, atropine

Non-heterocyclic

atypical

no n-atom in ring

protoalkaloid (biogenic/alkaloidal amine)

Ex. Colchicine

True alkaloids

Derived from amino/anthranilic acid + heterocyclic ring

Ornithine

Tyr

Trp

His

Anthranilic acid

True alkaloids are derived from:

Ornithine

Pyridine-Piperidine, Tropane

Tyrosine

Isoquinoline

Tryptophan

Indole

Histidine

Imidazole

Anthranilic acid

Quinolone, Quinazoline

Protoalkaloids

Amino acid + non heterocyclic ring

biogenic/alkaloidal amine

Pseudoalkaloids

not derived from amino acid + heterocyclic ring

heterocyclic: steroidal & purine