PHG 322 lecture 5

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‫بسم هللا الرحمن الرحيم‬
PHG 322
PHARMACOGONSY II
LECTURE 5
PRESENTED BY
ASSISTANT PROF. DR. EBTESAM ALSHEDDI
Indole Alkaloids
4- Rauwolfia Alkaloids (carboline alk.)
• Source: Rauwolfia roots (Rauwolfia
serpentina, Fam. Apocynaceae)
Carboline skeleton
• Constituents: The most important are Reserpine, Deserpine and
Rescinnamine.
• Properties:
 Reserpine and related alkaloids are weakly basic diester,
tertiary alkaloids and possess a carboxylic group on ring "E".
N
H3CO
N
H
E
H3COOC
R= 3,4,5-trimethoxybenzoic acid
R= 3,4,5-trimethoxycinnamic acid
OR
Reserpine
Recinnamine
 Alkaline Hydrolysis:
1- Reserpine → reserpic acid + trimethoxybenzoic acid + methanol.
2- Recinnamine → reserpic acid + trimethoxycinnamic acid + methanol.
 Its solution acquires a yellow color and a pronounced fluorescence especially
after the addition of acids or upon exposure to light.
• Tests for reserpine:
 Vanillin /HCl reagent: → violet color.
 Sodium molybdate in H2SO4 → Yellow → Blue in two minutes.
• Uses:
 Reserpine and the related alkaloid rescinnamine are mainly used as
antihypertensives (250-500 mg daily) and as tranquilizers (0.1- 1mg or more
daily).
Imidazole Alkaloids
Pilocarpus Alkaloids
• Source: Jaborandi leaves (Pilocarpus jaborandi).
• Constituents: (+)-Pilocarpine.
• Properties:
N
1- Oily liquid miscible with water.
2- Non-volatile liquid alkaloid.
N
3- Lactone function.
CH3
• Test:
Helche’s test:
Alkaloid + Dil acid + K2CrO7 → violet colour
(Pilocarpine dichromate)
• Uses:
1- Miotic.
3- Hair preparations.
2- Diaphoretic.
O
O
Effects/Uses:
 Pilocarpine is a cholinergic agent causing
constriction of the pupil (Antagonistic to Atropine).
 Pilocarpine salts are valuable in ophthalmic practice
and are used in eye drops as miotics and for the
treatment of glaucoma.
 Pilocarpine gives relief for dryness of the mouth that
results in patients undergoing radiotherapy for mouth
and throat cancers.
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Tropolone Alkaloids
Colchicum Alkaloids
• Source: Colchicum Corm.
• Constituents: Colchicine.
H3CO
• Properties:
H3CO
1- Neutral Alkaloid.
OCH 3
2- Amid function.
• Test:
1- Red colour with FeCl3.
2- Yellow colour with dil. Mineral acids.
• Uses:
1- Treatment of Gout.
2- Anticancer in vitro.
3- Treatment of Mediterranean Sea fever.
4- Polyploidy in Plants.
NH-CO-CH 3
O
OCH 3
Alkaloids with Exocyclic Nitrogen
(Protoalkaloids- Phenylalkylamines- Biological amines)
 This group of alkaloids have the nitrogen atom located
in an amino group and is not a member of a
heterocyclic ring

Many are simple derivatives of Phenylethylamine and as
such, are derived from the common amino acids
Phenylalanine or Tyrosine.
H
CH2 C COOH
NH2
phenylalanine

H
HO
CH2 C
COOH
NH2
tyrosine
They are sympathomimetic drugs (e.g. rise the blood
pressure).
Protoalkaloids includes the alkaloids of:
1) Ephedra alkaloids
2) Khat alkaloids
3) Peyote alkaloids
Alkaloids with Exocyclic Nitrogen
(Protoalkaloids- Phenylalkylamines- Biological amines)
1- Ephedra Alkaloids
 Source: Ephedra Herb (Ma Huang, Yellow Hemp).
especially Ephedra sinica (Family
Ephedraceae). *
 Ephedra used as remedy for Asthma in Chinese medicine.
 (-)-Ephedrine is the major Alkaloid in Ephedra.
 Ephedrine is a phenylalkylamine with N atom in the side
chaine
• Ephedrine is similar to adrenaline in structures.
• Advantages of Ephedrine over adrenaline:
1- Orally active.
2- Prolonged action
Adrenaline is used to treat a number of conditions including: cardiac
arrest, anaphylaxis, and superficial bleeding. It has been used historically
for bronchospasm and hypoglycemia, but newer treatments for these, such
as salbutamol, a synthetic epinephrine derivative, and dextrose,
respectively, are currently preferred.[8]
Effects/Uses of Ephedrine

Its pharmacological action resembles epinephrine (adrenaline),
but is considerably less active.

Ephedrine can be absorbed orally, unlike epinephrine.

Ephedrine increases blood pressure and heart rate.

It is a potent nasal decongestant due to its vasoconstrictor action
on blood capillaries of mucous membranes.

Ephedrine has a longer duration of action.
Chen’s test:
Ephedrine HCl in water + 0.1 ml CuSO4 + 1ml NaOH → Violet
colour, shake with Ether →
Ether layer
→ purple
Aqueous layer → blue
2- Cathe Alkaloids (Kat ‫)القات‬
Khat or “ Abyssinian tea” consists of the
fresh leaves of Catha Edulis (Family
Celastraceae).
CNS stimulant activity
 Abused drug.

OH
CH
O
CH
CH3
C
NH2
Cathine
CH
NH2
Cathinone
CH3
3- Peyote Alkaloids
• Source: Lophophora williamsii ( is a
small, spineless cactus)
• Hallucinogenic
• Major alkaloid
H3CO
NH2
H3CO
OCH 3
Mescaline
Purine alkaloids
Purines are derivatives of a heterocyclic nucleus consisting of a
six-membered Pyrimidine ring fused to a five-membered
Imidazole ring.
Purines are Psudo alkaloids (Are not derived from amino acids
but have nitrogen in a heterocyclic ring)
(True alkaloid- protoalkaloid- pseudoalkaloid)
Purine alkaloids
xanthine
coffeine

theobromine
They are all methyl derivatives of xanthine.
theophyilline
Chemical test:
 Do not give precipitate with Mayer's reagent.
 They give a positive Murexide test (special test).
* are weak bases form salts only with strong acids
22

Caffeine:
Is the best CNS stimulant of the purine bases and has weak
diuretic action.
Source:
Coffee seeds – Sеmina Coffeae
Arabian coffee tree -Coffea arabica
Fam. – Rubiaceae
Added to the analgesics

Theobromine:
Has little CNS stimulant action, but has more diuretic activity,
and has smooth muscle relaxant effect.
From Theobroma cacao tree
 Theophylline:
Has low CNS stimulant action and is an effective diuretic, but it is an important
smooth muscle relaxant & used for relief of bronchial spasms.
Tea Leaves – Folia Theae
Chinese Tea – Thea sinensis
Family Teas – Theaceae
Marine Bioactive Agent
• Over 70% of the earth's surface is covered by oceans
which contain 95% of the earth's biosphere
• Marine environments are considered more
biologically diverse than terrestrial environments
• Ocean contain highly ecological, chemical &
biological diversity starting from micro-organisms to
vertebrates. This diversity has been the source of
unique chemical compounds, which hold
tremendous pharmaceutical potential.
•
• Marine Bioactive Agent, Marine bioactive
compounds or Marine natural products (MNPs)
are organic compounds produced by microbes,
sponges, seaweeds, and other marine organisms.
The host organism synthesizes these compounds
as secondary metabolites to protect themselves
and to maintain homeostasis in their
environment.
•
• Marine organisms are able to generate
bioactive compounds to protect themselves
from external factors.
• Recently, scientists have explored various
health beneficial pharmaceutical bioactives
from marine bio resources such as
macroalgea, microalgea, fungi, bacteria,
actinomycetes, invertebrates and vertebrates.
• The number of potential compounds isolated
from marine exceeds to 10000
• with hundred of new compounds still being
discovered every year
• A number of promising identified molecules
are already in market, clinical trials or
preclinical trials

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