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SECONDARY METABOLITE PRODUCTION
INTRODUCTION
Higher plants synthesize a wide variety of low molecular weight compounds in addition to the essential primary metabolites. These are called secondary metabolites
These secondary metabolites offer protection against pests,they act as attractatnts and as the plant’s own hormones
WHY SECONDARY METABOLITES
Chemically warfare to protect plants from the attacks by predators, pathogens, or competitors
Attract pollinators are seed dispersal agentImportant for abiotic stressMedicineIndustrial additives
CLASSIFICATION OF SECONDARY METABOLITES
They are classified on the basis of 1)chemical structure 2)chemical composition 3)solubility in various solvents 4)pathways by which they are
synthsized
A simple classification of secondary metabolites includes three main groups
1)the terpenes- made from mevalonic acid, composed almost entirely of carbon and hygrogen
2) phenolics – made from simple sugars, containing benzene rings, hydrogen and oxygen
3) nitrogen-containing compounds – extremely diverse, may also contain sulphur
ALKALOIDS
Most are derived from a few common amino acids (i.e..tyrosine , tryptophan , ornithine or argenine and lysine
Compounds have a ring structure and a nitrogen residue
Indole alkaloids is the largest group in this family , derived from tryptophan
Widely used as medicine
CHARACTERISTICS
They are bitter in taste. Derived from amino acids.The amino acids that are
most often serve as alkaloidal precursors are: phenylalanine, tyrosine, tryptophan, histidine, anthranilic acid, lysine and ornithine.
Alkaloids form double salts with compounds of mercury, gold, platinum and other heavy metals. These salts are obtained as precipitate which are microcrystals.
Insoluble or sparingly soluble in water, but the salts formed on reaction with acids are usually freely soluble.
Most are crystalline solids although a few are amorphous.
Free alkaloids are usually soluble in polar solvents like ether, chloroform
Some alkaloids are liquid because of lacking of oxygen in their molecules. (e.g coniine, nicotine, spartenine)
Sources and Occurrence of Alkaloids
Alkaloids can occur in plant kingdoms; among the angiosperms,
Leguminosae, Papaveraceae, Ranunculaceae, Rubiaceae, Solanaceae,
Berberidaceae are outstanding alkaloid-yielding plants.
Uses of Alkaloids in Plants:
Poisonous agents which protect plants against insects
and herbivores
End products of detoxification reactions representing a
metabolic locking-up of compounds otherwise harmful to
the plants.
For regulatory growth factors
Reserve substance capable of supplying nitrogen or
other elements necessary to the plant’s economy
TERPENES
Terpenes are natural products that are structurally related to isoprene
Isopropene (2-methyl-1,3-butadiene)
H2C C
CH3
CH CH2OR
1. The number of C atoms is a multiple of 5, C5
C10 C15 C20 C25 C30 C35 C40
2. Each group of 5 C is an isoprene subunit3. They can be saturated or unsaturated4. Many contain O atoms as well.
PHENOLICS
• Derived from aromatic amino acids, such as phenylalanine, tyrosin, and trytophan.
• All contain structures derived from phenol• Some examples:
Coumarins: antimicrobial agents, feeding deterrents, and germination inhibitors.
Lignin: abundant in secondary cell wall, rigid and resistant to extraction or many degradation reagents
Anthocyanins Flavones Flavnols Phenols are present in every plant they attract pollinators to the plant
and even impact how these plants act with one another. .
GLYCOSIDES
• Compounds that contain a carbonhydrate and a noncarbohydrate
• Glycosides are present in vacuoles in inactive form
• Glucosinolates: found primarily in the mustard family to give the pungent taste
There are four type of linkages present between glycone and aglycone:
C-linkage/glycosidic bond, O-linkage/glycosidic bondN-linkage/glycosidic bondS-linkage/glycosidic bond
Sources and effects of major secondary metabolites
carotenoids are organic pigments occuring in plants and are mostly found in red orange and yellow fruits and vegetables .
they have antioxidative effects and prevents cancer
They boost the immune system and reduce the risk of heart attacks
PHYTOSTEROLS
Found in- sunflower seeds ,sesame,nuts and soy beans
Protect against colon cancerand low cholestrol level
SAPONINS
Flavour additives found in- legumes and spinach
Boost the immune system
Lower the cholestrol level in blood
Reduce the risk of intestinal cancer
FLAVONOIDS
Organic pigment
Gives plant red violet or blue colour
Inhibit the growth of bacteria and viruses
Protect the cells against the damage of freeradicals
Influence blood coagulation
SULPHIDES
Contain sulphur
Belongs to the lily family onions ,leeks, asparagus, garlic
Inhibit the growth of bacteria
Lower cholestrol levels
Preventive efect against cancer
CURCUMIN
•Extracted from turmeric.•Coloring and medicinal uses•Wound healing•Antiulcer•Anti inflammatory•Antimicrobial & antiviral •Hepatoprotective•Antioxidant•No toxicity.
FLAVORSCocoa seedsVennilaStrawberryCinnamonCardamomClovesPepperareca
PRODUCTION OF SECONDARY METABOLITES IN CULTURES/BIOREACTORS
1)choice of explants any part of the plant can be used dicotelydons are rather amenable for
callus tissue induction procured explants are sterilized prior
to culture by using ethanol
2)NUTIENT CULTURE MEDIA
To induce callus from an explant and to cultivate the callus and cells in suspension
3)Callus induction
A callus cell culture is usually sustained on gel medium. Callus induction medium consists of agar and a mixture of macronutrients and micronutrients for the given cell type. There are several types of basal salt mixtures used in plant tissue culture, but most notably modified Murashige and Skoog medium White's medium, and woody plant medium. Vitamins are also provided to enhance growth such as Gamborg B5 vitamins. For plant cells, enrichment with nitrogen phosphorus, and potassium is especially important.
SUSPENSION CULTURE
The growth rate of suspension cultured cell is generally faster than that of the solid culture. The former is more desirable, particularly in the production of useful metabolites on a large scale
FERMENTORS OR BIOREACTORS
Carboy system-described by tulecke and nickell in 1959,consists of a rubber-stoppered 20 litre carboy fitted with four tubes. Filtered compressed air is employed for oxygen supply, aeration and agitation of the medium
Stirred jar fermetor- used for microbial cultivation
Agitation speed of 50 to 100 rpm
HAIRY ROOT CULTURE
It is the culture produced after the infection of explants and cultures by the gram negative soil bacteria Agrobacterium rhizogens
This process take advantage of the naturally occuring hairy root disease in dicotyledons
Agrobacterium recognizes some signal molecules exuded by wonded plant cells and becomes attached to it.The bacteria contain the Root inducing plasmid ( Ri-plasmid). The bacteria Genetically trasfer part of the
Ri-plasmid called the trasfer DNA (T-DNA) to the plant genome.
The plant cell to proliferate by increasing the rate of cell division ( cytokine expression ) and cell elongation (auxin expression) to produce the hairy roots.
Produce the opines which is a type of unusual amino acids ( octopine, agropine, nopaline, mannopine amd cucumopine) which is used by the bacterium as a carbon , nitrogen and energy source.
Induction of hairy root cultures In Vitro
Explants are wounded and then inoculated with Agrobacterium rhizogenes.
Usually two or three days later, the explant can be transferred into solid media with antibiotics, such as cefotaxime , vancomycine or ampicillin to kill or eliminate redundant bacteria.
The hairy roots will be induced within a short period of time, which varies from one week to over a month depending on different plant species.
The decontaminated hairy roots can be subcultured on phytohormone –free medium.
Commercial production of secondary metabolites
higher plants contain a variety of metabolic products which are useful as medicines ,food additives,perfumes,etc. however , non-compromising reduction in plant sources,increases in labour cost and other problems in order to obtain these high value added substances from natural plants ,have forced to develop analternative approachtowards the use of plant cell culture for production of these metabolic products .since ptc is not affected by changes in environmental conditions such as climate or natural depredation, improved production is possible
PHARMACEUTICALLY IMPORTANT CHEMICALS
1)Morphine alkaloids
Codeine is an anlagesic and cough suppressing drug from Papaver somniferum
also morphine can be converted into codeine
many workers have tried to produce codeine by undifferentiated cells of these plants
BERBERINE
it is an isoquinoline alkaloid which is produced and distibuted in roots of Coptis japonica and cortex of Phellonderon amurense Berberine chloride is used in treatment of intestinal disorders
TORPANE ALKALOIDS
Scopolamine and hyoscyamine areused commercially as anesthetic and antispasmodic drugs.
Occur in the leaves of members of the family Solanaceace including Duboisia myoporoides Datura leichhartdtti, Scopolia, Atropa,and Hyoscyamus
ANTITUMOUR COMPOUNDS
VINCA ALKALOIDS
Extracted from Catharanthus roseusTreat leukemias, hodgkin’s disease and antitumor activity
GINSENG
Roots of Panax ginseng is widely used as tonicEffective for genetic disorders, diabetes and weak circulationRoot contains saponins and sapogeninis
FOOD COLORING AGENTS
SAFFRON
Made from the stamens of Crocus sativus and used as flavouring agent and colourant
Plant contains crocin(yellow pigment), safranal(fragrance), picocrocin(bitter substance)
Baked goods, soaps, cheese
Medicinal value for stomach ailments
SAFFLOWER YELLOW
Yellow pigment obtained from the floret of the Carthamus tinctorius
Major pigment is carthamin
Carthamin is a quinoid form of isocarthamin
Used in baked goods and beverages
CHEWING GUMS CHICLE
Chicle a raw material is obtained from the latex of Achras sapota
Chicle contains 60% resin and 15% of rubber
Resin consisits of lupeo,α-amyrin andβ-amyrin
Rubber consists of cis and trans- 1,4-polyisoprene
Synthesized through mevalonic acid pathway
TAXOL
It is a ditrpene amideExtracted from the bark of wild grown Taxus brevifoliaTreats breast and lung cancer