PHG 322 lecture 6

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Transcript PHG 322 lecture 6

‫بسم هللا الرحمن الرحيم‬
PHG 322
6 kingdoms of marine organisms
• Bacteria are single-celled organisms that reproduce by splitting in two. Bacteria live throughout the
marine environment. They play a crucial role in ecosystems, breaking down organic material and
making nutrients available for the phytoplankton.
• Protozoans are single-celled organisms that are generally much larger than bacteria. They may be
autotrophic or heterotrophic. In the marine environment, this kingdom is well represented and
includes amoebae.
• Chromists range from very small organisms such as diatoms (a type of phytoplankton) to
seaweeds. Most chromists photosynthesise but there are some significant differences that have led
scientists to classify them separately to plants, for example, they use a different kind of chlorophyll.
• Fungi rely on breaking down organic material as they are not able to make their own food. There are
very few fungi in the marine environment.
• Plants are multi-cellular and autotrophic – they use photosynthesis to produce food using sunlight.
Plants are much more widespread on land and in freshwater, and there are only a few types that thrive
in the marine environment, for example, eel grass and mangroves. Seaweeds were previously classed
as plants before they were reclassified as chromists.
• Animals are typically large and multi-cellular. They are heterotrophic and rely on other organisms
for food. Animals in the marine environment include jellyfish, sponges, sea spiders, bryozoans,
mussels, sea stars, fish and whales.
 Sources of marine bioactive compounds include:
Marine algae
(= Seaweeds)
Marine bacteria and
Marine algae
• Grow almost exclusively in the shallow waters at the edge of the world's oceans
• Seaweeds are plants because they use the sun's energy to produce
carbohydrates from carbon dioxide and water.
• They are simpler than the land plants mainly because they absorb the
nutrients that they require from the surrounding water and have no need for
roots or complex conducting tissues
• Seaweed draws an extraordinary wealth of mineral elements from the sea
which includes sodium, calcium, magnesium, potassium, chlorine, sulfur
and phosphorus; the micronutrients include iodine, iron, zinc, copper,
selenium, molybdenum, fluoride, manganese, boron, nickel and cobalt
• vitamins like carotenes (provitamin A); vitamin C, B12 along with higher
proportion of essential fatty acids than land plants.
Marine algae (cont.):
 Can be classified into three broad groups based on their color:
(= Phaeophyceae)
(= Rhodophyceae)
Brown seaweeds
Red seaweeds
(= Chlorophyceae)
Green seaweeds
 Are usually large
 Are usually smaller
 Also small
 Range from:
- Giant size (20 m
 Range from:
- Few centimeters
to about 1 m in
 Similar in size to
red seaweeds
Thick, leatherlike seaweeds
from 2 – 4 m
Small species
30 – 60 cm long
 Not always red,
sometimes purple
Brown algae
Red algae
Green algae
 Seaweeds are also called “macroalgae”.
 This distinguishes them from “microalgae” which are:
Microscopic in size
Often unicellular and
Are best known by the “blue-green” algae that
contaminate rivers and streams.
Cyanobacteria (blue-green algae) are microorganisms that
structurally resemble bacteria (they lack a nucleus and
organelles ). However, unlike other bacteria, cyanobacteria
contain chlorophyll a and conduct oxygenic photosynthesis
 Phycology (from Greek, phykos, "seaweed” and -logia) is the
scientific study of algae.
 Sources of bioactive compounds (cont.):
2) Marine bacteria and fungi:
Of considerable importance as new
promising sources of biologically
active products.
 Up till now, only a small number of
microorganisms have been
investigated, yet a huge number of
active substances have been
isolated e.g. some antibiotics.
It was surprising to find that many bioactive compounds, reported from
marine invertebrates are produced by their microbial symbionts
Interestingly microorganisms associated with marine invertebrates are
proved valuable candidates for drug discovery program
 Sources of bioactive compounds (cont.):
3) Marine invertebrates:
They are animals that inhabit a marine environment and
are, lacking a vertebral column.
In order to protect themselves, they may have evolved a
shell or a hard exoskeleton, but this is not always the case.
 Bioactive metabolites have been isolated from many
invertebrates among these are:
marine sponges, jellyfish, tunicates, bryozoans, sea hare
and others.
Marine sponges:
 They are sessile animals that filter
water through their porous bodies.
 They ingest food particles and
dissolved materials.
Marine sponges known to be a very rich source of terpenoids , halogenated alkaloids and
Polyacetylenenic alcohols
 Jellyfish:
 They are free-swimming animal.
 The body of the jellyfish consists of more
than 95% of water and less than 5% of organic
 When removed from water, they collapse
 Their body is a sack with two siphons
through which water enters and exits.
 Water is filtered inside the sack-
shaped body.
 They are living for the most
part in colonies of
interconnected individuals.
Sea hare:
 The common name is derived from:
The two long rhinophores that
project upwards from their heads
→ They resemble the ears of a hare
 Biomedical potential of marine natural
 In recent years, published reviews clearly indicate the
tremendous potential of marine organisms as a source of
new pharmaceuticals.
 Classes of bioactive compounds include:
1) Antiviral substances
2) Cytotoxic compounds
3) Antiparasitic compounds
4) Anticoagulants
 Classes of bioactive compounds include: (cont.)
5) Antimicrobial agents
6) Anti-inflammatory compounds
7) Toxins
Some of the commercialized products
• Also known Ara-A
• From sponge
• Nucleoside it combines a adenosine base with
an arabinose sugar
• Antiviral (herpes virus)
• also known as Ara-C (Arabinofuranosyl
• From sponge
• it combines a cytosine base with an arabinose
• Anticancer
Kainic acid
• Anthelmintic
• From seaweed
• From cone snail
• Peptide
• Analgesic
• From sponge
• Anticancer
• Macrolide
• From fish
• Omega-3-fatty acid
• Hypertriglyceride
• From tunicate
• Alkaloid
• Anticancer
Antiviral compounds
• From sponge
• The search for new antiviral agents from marine sources
particularly sponges yielded several promising therapeutic
1. Ara-A (Adenine arabinoside):
• Vidarabine or Ara-A is a synthetic analogue of spongouridine
with improved antiviral activity.
• Spongouridine isolated from the Caribbean sponge Tethya
• Vidarabine is an inhibitor of viral DNA synthesis
• Active against Herpes viruses
• 2- Avarol and avarone
a sesquiterpenoid hydroquinone or quinone
isolated from the marine sponge Disidea avara
inhibitory effect
on the replication of the etiologic agent of Acquired Immune Deficiency
Syndrome (AIDS)
• From tunicate
• 1- Patellazole B:
 A thiazole-containing macrolide.
 It showed very potent in vitro activity
against Herpes simplex viruses.
 It was isolated from the tunicate Lissoclinum patella.
• 2- Didemnins
are cyclic depsipeptide compounds
isolated from a tunicate (sea-squirt) of the genus Trididemnum
Active against herpes simplex virus type 1
Didemnin B also showed antitumor activity
• 3- Eudistomins
• Isolated from Eudistoma olivaceum
• A family of β-carbolines
• From seaweed
• 1- sulphated fucan
isolated from the brown seaweed Cystoseira indica
Are polysaccharide
have potent antiviral activity against herpes simplex virus types 1
(HSV-1) and 2 (HSV-2)
• 2- Sphingosine derivative
• an 18-carbon amino alcohol