Cyanobacterial Extra-Metabolites Collected By Abobakr
Abdull-Mohsin Aazzam Arashad Supervisor Pro. Dr. Ibraheem Borie
2
Slide 3
Introduction Primary metabolite : a metabolite is directly
involved in normal growth, development, and reproduction. Secondary
metabolites : also known as natural products, are those products
(chemical compounds) of metabolism that are not essential for
normal growth, development or reproduction of an organism. In this
sense they are "secondary". 3
Slide 4
Fig. 1. Main pathways of some secondary and primary metabolites
biosynthesis 4
Slide 5
Soluble extracellular products Blue green algae, in general,
inhabit aquatic environments so it is possible for organic
substances to enter algal cells from the environment and so the
possibility must be considered that the passage of similar
substances can take place equally readily in the opposite direction
with the result that appreciable proportions of the products of
metabolism are liberated in extracellular form from healthy algal
cells. 5
Slide 6
Cyanobacteria are well-known producers of secondary metabolites
of different chemical structures and a wide range of biological
functions. Cyanobacteria such as Microcystis, Anabaena, Nostoc and
Oscillatoria produce a great variety of secondary metabolites.
6
Slide 7
The nature of the extracellular compounds of Anabaena
cylindrica has been found to liberate extracellular pentose in
amounts of up to 1-4% of its dry weight as well as nitrogenous
substances which may represent a considerably greater proportion of
the total carbon fixed by the alga. It is to be noted that the
dissolved organic matter to be found both in freshwater and
seawater consists principally of substances of a nitrogenous nature
and of pentosans. 7
Slide 8
Organic acids, alcohols and other extracellular products
commonly found in cultures of bacteria and fungi have never been
found in appreciable quantities in filtrates from blue green algal
cultures. Extracellular nitrogenous products in cultures of
nitrogen fixing algae have been noted. 8
Slide 9
Cyanobacteria produce a wide variety of toxins and other
bioactive compounds, which include: 40% lipopeptides 5.6% amino
acids 4.2% fatty acids 4.2% macrolides 9% amides. Cyanobacterial
lipopeptides include different compounds like: Cytotoxic (41%)
Antitumor(13%) Antiviral (4%) Antibiotics(12%) The remaining 18%
activities include antimalarial, antimycotics, multi-drug
resistance reversers, antifeedant, herbicides and immunosuppressive
agents ( see the following tables). 9
Slide 10
10 The following Tables summarizing Compounds isolated from
cyanobacteria
Slide 11
11 Tables summarizing Compounds isolated from
cyanobacteria
Slide 12
12
Slide 13
13
Slide 14
14
Slide 15
15
Slide 16
16
Slide 17
17
Slide 18
Carbohydrates and related substances Carbohydrates may occur in
considerable proportions in blue green algae either as
intracellular reserve materials or as cell wall constituents and
more is known of this class of algal product than of any other.
Most of the carbohydrates are built up from units containing a
heterocyclic six-membered, or pyranose, skeleton. 18
Slide 19
Goryonora 1950: discovered secretion of carbohydrates from
Oscillatoria splendida within culture media. Fogg 1952: discovered
7mg/L of secreted pentose from Anabaena cylindrica. Bishop et al
1954: identified this pentose, consisting of glucose xylose,
glocoronic acid,galactose, rhamnose and arabinose Glucose,or other
reducing sugars, occur in low concentrations forming the principal
intracellular reserve products 19
Slide 20
Nitrogenous substances Little is known of the proteins of algae
and as yet only amino- acid analyses of the bulk proteins of
certain species are available. Many researches found cyanobacteria
secrete large quantity of soluble peptides. Peptides can be
classified, based on their common characteristics of chemical
structure, into six classes: aeruginosins, microginins,
anabaenopeptins, cyanopeptolins, microcystins, microviridins and
cyclamides Cyanobacteria contains all of the essential amino acids
as well as most of the nonessential amino acids. 20
Slide 21
TABLE.1.The amino acids of some cyanobacteria compared with
some eukaryotic algae and higher plant Amounts are given as g.
amino-acid N/100 g. protein N 21
Slide 22
Certain amino-acids other than those mentioned in Table 1 may
be characteristic of particular classes. Diaminopimelic acids exist
in Anabaena cylindrica and Oscillatoria sp. Some nitrogenous
substances released from cyanobacteria as secondary products of
protein assimilation as it formed during active growth. Other
nitrogenous products of algae have received little attention.
22
Slide 23
Fatty acids The cyanobacteria produced large amounts of
linoleic and linolenic acids, whose content in some strains
exceeded 50% of total FA. 23
Slide 24
Major fatty acids isolated from coccoid unicellular blue-green
algae: genera Aphanocapsa, Gloeocapsa, Microcystis, Chlorogloea
24
Slide 25
Vitamins and growth substances Cyanobacteria may play a role as
producers of vitamin B12 especially Anabaena flos-aquae and
Spirulina sp. Some blue green algae also contains high amounts of
both cis and trans forms of beta carotene (a precursor to Vitamin
A) Leferve & Takob 1949:dicovered growth-enhancing substances
secreted from some blue green algae and can affect on other. Auxins
(plant growth substances and morphogens) were isolated from marine
water containig some Oscillatoria species. 25
Slide 26
Enzymes Some blue green algae capable growth chemotropically
such as Nostoc punctiforme produce enzymes as extrametbolites due
to utilizing starch and other high molecular weight molecules as a
carbon source. -Lactamase (penicillinase) activity was found in a
number of strains of blue-green algae such as Coccochloris
elabens(strain 7003), and Anabaena species (strain 7120). Some blue
green algae produce different types of enzymes such as phytase,
Lipoxygenase, Glycolate Dehydrogenase,etc.. 26
Slide 27
Organic acids Some autotrophic blue green algae,such as
Oscillatoria splendida,secrete some organic acids such as :Succinic
acid, Tartaric acid and Oxalic acid. Some chemotrophic blue green
algae secrete some organic acids such as Lactic acid as result of
glucose fermentation 27
Slide 28
Auto-inhibitors & antibiotics Some studies showed
antibiotic activity of new cyanobacterial secretions on another
organisms such as eukaryotic algae. Auto -inhibition occurs as
result of metabolitie accumulation in culture media at stationary
phase such as Nostoc punctiforme. The naturally occurring
nucleoside/nucleotide antibiotics which have been isolated from
blue-green algae, they have antimycoplasmal, antiviral,
hypotensive, antifungal, antimycobacterial, and antitumor
activities and induce sporulation. A number of compounds in
cyanobacteria are inhibitors of proteases micropeptins,
cyanopeptolins, oscillapeptin, microviridin, aeruginosins- and
other enzymes 28
Slide 29
Toxins Some authors defined two basic groups of cyanobacterial
secondary metabolites based on their biological effects: Biotoxins:
causing death to higher organisms. cytotoxins, compounds causing
inhibition to cell cultures or single cell organisms.
Themicrocystins, cylindrospermopsin, homo- and anatoxin-a,
anatoxin-a(s) and saxitoxins are the most common algae toxins and
are associated with Microcystis, Anabaena, Oscillatoria and Nostoc
species. 29
Slide 30
Fig. 2. Possible implications of cyanobacterial secondary
metabolites for aquaculture species 30
Slide 31
High value metabolites from Cyanobacteria Cyanovirin-N: against
HIV-1. Borophycin: against carcinoma, antimicrobial activity
Cryptophycin: fungicide. Lipopeptides: anticancer, antibiotic,
enzyme inhibitor, antiviral and antifungal activities. Carotenoids
: antioxidant properties. Sulfonic acid :Antiviral Effect (such as
HIV). Sulphated polysaccharide &calcium spirulans: inhibit
tumor invasion and metastasis. Alkaloids:(such as
hydroxymanzamine):Antituberculosis Activity. 31
Slide 32
Compounds That Only Occur in Algae and Their Metabolism Enzymes
of glycolate metabolism, through to the polyglucan organic carbon
stores that act as a metabolic buffer between organic carbon
production (or acquisition) and downstream metabolism.
Alga-specific endproducts such as extracellular structural
materials (e.g. agarose, agaropectin, alginic acid and
carrageenans) and anti-biophage compounds and compatible solutes of
widespread occurrence but with alga-specific synthetic pathways
(e.g. dimethylsulfoniopropionate). 32
Slide 33
Metabolites from Blue- Green algae with economical impact Blue
green algae are promising organisms for providing both novel
biologically active substances and essential compounds for human
nutrition. Both secondary and primary metabolisms have been studied
as a prelude to future rational economic exploitation. The
secondary metabolism is of restricted distribution, while the
primary metabolism furnishes intermediates for the synthesis of
essential macromolecules 33
Slide 34
Biosynthetic studies have been few and mainly concerned with
secondary metabolism, which present a high structural diversity,
due to modifications and combinations of reactions from the primary
metabolic pathways. Emergence of molecular biology tools, metabolic
pathways have been clarified, paving the way for generating novel
bioactive metabolites in quantity by genetic engineering. The main
substances biosynthesized by blue green algae with potential
economic impact in food science, pharmaceutical industry and public
health. Emphasis is given to fatty acids, steroids, carotenoids,
polysaccharides, lectins, mycosporine- like amino acids,
halogenated compounds, polyketides and toxins. 34
Slide 35
Factors affecting on execration rate of extrametbolites Light
intensity. PH. Temperature. Salinity. Mutation. Nature of culture
media. Number of cells(Fogg 1952,1958). 35
