Alkaloids Flashcards
most important and common feature of alkaloids
they contain an nitrogen atom in a heterocycle and bitter tasting and basic
typical alkaloids are …
derived from plant sources
they are basic
contain one or more nitrogen atoms
have a physiological action on humans or other animals
examples of common alkaloids
caffeine and nicotine
important families of alkaloids
apocyanceae (Dogbane)
Papveraceae (Poppy)
Fabaceae (leguma, pea)
Ranunculaceae (Buttercup)
Rubiaceae (Coffee, Madder)
Rutaceae (Rue or Citrus)
Solonaceae (Nightshades)
applications of alkaloids
medicinal - virtually every pharmaceutical applicaiton imaginable except antibiotic
agriculture - insectisides and veterinary
culturl/entheogenic - most often to idnuce an altered state of consiousness.
recreational - nicotine
testing for alkaloids
mayer’s - cream colour
dragendorffs’s - orange
wagner’s reagent - red/brown
hager’s reagent - yellow
physicochemical properties
most alkaloids that don’ contain oxygens are liquid at room temp
insoluble in water
soluble in polar or slightly polar organic solvents
how are alkaloids classified
according to their origin
eg acontium, amaryllidaceae, ergot, opium etc
chemical classification
True alkaloid
Proto alkaloid
Pseudoalkaloids
False Alkaloids
what are true alkaloids
they are derived from an amino acid and have a nitrogen in a heterocyclic ring
what are proto alkaloids
they are derived from an amino acid but their nitrogen atom is not in the heterocyclic ring
what are pseudo alkaloids
they are not derived from amino acids but the nitrogen atom is in the heterocyclic ring
what type of derived alkaloids are there
there is tryptophan, Phenylalanine/ tyroise
what pathway and compound produce the precursor for the derived alkaloid pathway
the shikimata pathway with the compound chroismate.
indole alkaloids
tryptophan poduct of tryptamine give rise to the indole alkaloids.
these contian 2 nitrogen, on is indolic nitrogen and the second is generally two carobons removed from the b-position of the indole ring.
what determines the type of alkaloid produced for the tryptophan reactions
condensation between tryptamine and an aldehyde or a keto acid.
with the rection either occuring at the alpha or beta carbon.
what terpene pathway is also used for alkaloids
the mevalonate pathway as it is used for non-trypotophan derived
what families does a c10 monoterpenoid provide
the apocynaceae. loganiaceae and rubiaceae
example of tryptophan derived alkaloid
physostigmine
used to treat glaucoma
originally used as a poison
ergotamine
is a tryptophane derived alkaloid,
structural similiarity to several neurotransmitters
functions as a vasoconstrictor
used to treat acute migraine
vinblastine
tryptophane derived,
obtianed from Catharanthus roseus (madagascar periwinkle)
a funsion of two alkaloid precursors
potent mitotic inhibitor used to treat a umber of types of cancer
phenylalanine and tyrosine are ?
essential, aromatic amino acids
benzylisoquinoline and opium are
well known derivatives of aromatic amino acids
amaryllidaceae alkaloids
well known for toxic properties
derived from one phenylalanine and one tyramine
represented by haemanthamine, lycorine, galantamine
potential treatment of galanthamine
Tetrahydroisoquinoline
derive from the condensation of dopamin with secologanin (c10 monoterpene)
cephaelis gives ipecacuanha root
emetine
earliest use of emtine is an emetic.
antiprotozoal,
Ornithine-derived alkaloid
the amino acid ornithine, makes the decarboxylation product putrescine, and proline constitute the basic unit of tropane, ecgonine, nicotine and others
what are the two major ornithine-derived alkaloid groups
tropane and pyrrolizidine
Tropane alkaloid
medical interest in atropine and hyoscine
these are both contained to nightsades
Atropine
comes from deadly nightshade, dilates the pupils, increase heart rrate, reduces salvation and other secreations
used to treate nerve gas poisoning
Hyoscine
antispasmodic used to prevent postoperative nausea and vomiting, treat gatrointestinal spasms,
Pyrrolizidine alkaloids
constitute the natural biocides from plants of genus senecio. these are well known for their toxicity to livestock
Piperine
used for cholera, dyspepsia
Cytisine
also known as baptitoxine or sophorine
currently used as an alternative to nioctine in replacement therapy
Biosynthesis of Protoalkaloid
derived from amino acids but do not have the nitrogen in a heterocyclic ring
are typically classified by what amino acid they came from
Ephedra species
original source of ephedrine and pseudoephedrine
Extraction methods for Alkaloids
Acidic or Basic
choice depends on the chemical state of the particular alkaloid
sample preparation
defatting using a non polar solvent which removes the interfering compounds
Basic Extraction
Moistend with water and mixed with a base so alkaloid is released.
organic solvents used for extraction by seperation. alkaloid salts igrate to teh aqueous phase.
Acid Extraction
moistened with water or aqueous alcohol. unwatned materials removed with shaking with chloroform.
free alkaloids are precipitated by the addition of excess sodium bicarbonate or ammonia and separated with filtration
