Polyketides are secondary metabolites from bacteria, fungi,
plantPlants are living organisms belonging to the kingdom Plantae. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The scientific study of plants, known as botany, has identified about 350,000 extant species of plants, defined as seed plants,...
s, and
animalAnimals are a major group of mostly multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously...
s. Polyketides are
biosynthesizedBiosynthesis is an enzyme-catalyzed process in cells of living organisms by which substrates are converted to more complex products. The biosynthesis process often consists of several enzymatic steps in which the product of one step is used as substrate in the following step...
by the
polymerizationIn polymer chemistry, polymerization is a process of reacting monomer molecules together in a chemical reaction to form three-dimensional networks or polymer chains...
of
acetylIn organic chemistry, acetyl is a functional group, the acyl with chemical formula COCH3. It is sometimes abbreviated as Ac . The acetyl group contains a methyl group single-bonded to a carbonyl...
and propionyl subunits in a similar process to fatty acid synthesis (a
Claisen condensationThe Claisen condensation is a carbon-carbon bond forming reaction that occurs between two esters or one ester and another carbonyl compound in the presence of a strong base, resulting in a β-keto ester or a β-diketone...
). They are the building blocks for a broad range of
natural productA natural product is a chemical compound or substance produced by a living organism - found in nature that usually has a pharmacological or biological activity for use in pharmaceutical drug discovery and drug design...
s or are further
derivatizedDerivatization is a technique used in chemistry which transforms a chemical compound into a product of similar chemical structure, called derivative....
.
Polyketides are structurally a very diverse family of natural products with diverse biological activities and pharmacological properties.
Discussion
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Polyketides are secondary metabolites from bacteria, fungi,
plantPlants are living organisms belonging to the kingdom Plantae. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The scientific study of plants, known as botany, has identified about 350,000 extant species of plants, defined as seed plants,...
s, and
animalAnimals are a major group of mostly multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously...
s. Polyketides are
biosynthesizedBiosynthesis is an enzyme-catalyzed process in cells of living organisms by which substrates are converted to more complex products. The biosynthesis process often consists of several enzymatic steps in which the product of one step is used as substrate in the following step...
by the
polymerizationIn polymer chemistry, polymerization is a process of reacting monomer molecules together in a chemical reaction to form three-dimensional networks or polymer chains...
of
acetylIn organic chemistry, acetyl is a functional group, the acyl with chemical formula COCH3. It is sometimes abbreviated as Ac . The acetyl group contains a methyl group single-bonded to a carbonyl...
and propionyl subunits in a similar process to fatty acid synthesis (a
Claisen condensationThe Claisen condensation is a carbon-carbon bond forming reaction that occurs between two esters or one ester and another carbonyl compound in the presence of a strong base, resulting in a β-keto ester or a β-diketone...
). They are the building blocks for a broad range of
natural productA natural product is a chemical compound or substance produced by a living organism - found in nature that usually has a pharmacological or biological activity for use in pharmaceutical drug discovery and drug design...
s or are further
derivatizedDerivatization is a technique used in chemistry which transforms a chemical compound into a product of similar chemical structure, called derivative....
.
Polyketides are structurally a very diverse family of natural products with diverse biological activities and pharmacological properties. Polyketide
antibioticIn common usage, an antibiotic is a substance or compound that kills or inhibits the growth of bacteria...
s, antifungals, cytostatics, anticholesterolemics, antiparasitics, coccidiostatics, animal growth promoters and natural
insecticideAn insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine, industry and the household. The use of insecticides is believed to be one of the major factors behind...
s are in commercial use.
Examples
- Macrolide
The macrolides are a group of drugs whose activity stems from the presence of a macrolide ring, a large macrocyclic lactone ring to which one or more deoxy sugars, usually cladinose and desosamine, may be attached. The lactone rings are usually 14, 15 or 16-membered...
s
- Picromycin, the first isolated macrolide (1950)
- The antibiotic
In common usage, an antibiotic is a substance or compound that kills or inhibits the growth of bacteria...
s erythromycin AErythromycin is a macrolide antibiotic that has an antimicrobial spectrum similar to or slightly wider than that of penicillin, and is often used for people who have an allergy to penicillins. For respiratory tract infections, it has better coverage of atypical organisms, including mycoplasma and...
, clarithromycinClarithromycin is a macrolide antibiotic used to treat pharyngitis, tonsillitis, acute maxillary sinusitis, acute bacterial exacerbation of chronic bronchitis, pneumonia , skin and skin structure infections, and, in HIV and AIDS patients to prevent, and to treat, disseminated Mycobacterium avium...
, and azithromycinAzithromycin is an azalide, a subclass of macrolide antibiotics.Azithromycin is one of the world's best-selling antibiotics, and is derived from erythromycin; however, it differs chemically from erythromycin in that a methyl-substituted nitrogen atom is incorporated into the lactone ring, thus...
- The immunosuppressant
An immunosuppressant is any substance that performs immunosuppression of the immune system. They may either be exogenous, as immunosuppressive drugs, or endogenous, as e. g. testosterone...
tacrolimus (FK506)Tacrolimus is an immunosuppressive drug whose main use is after allogeneic organ transplant to reduce the activity of the patient's immune system and so lower the risk of organ rejection. It reduces T-cell and interleukin-2 activity...
- Polyene
Polyenes are poly-unsaturated organic compounds that contain one or more sequences of alternating double and single carbon-carbon bonds. These double carbon-carbon bonds interact in a process known as conjugation, which results in an overall lower energy state of the molecule.Organic compounds with...
antibioticIn common usage, an antibiotic is a substance or compound that kills or inhibits the growth of bacteria...
s
- Tetracycline
Tetracycline is a broad-spectrum polyketide antibiotic produced by the Streptomyces genus of Actinobacteria, indicated for use against many bacterial infections. It is a protein synthesis inhibitor. It is commonly used to treat acne today, and more recently, rosacea, and played a historical role...
s
- The tetracycline family of antibiotic
In common usage, an antibiotic is a substance or compound that kills or inhibits the growth of bacteria...
s
- Acetogenins
- Annonacin
Annonacin is a chemical found in fruits such as the guanabana. It is a member of the class of compounds known as acetogenins. Recent reports have shown that daily consumption in rats caused brain lesions consistent with Parkinson's disease....
- Uvaricin
Uvaricin is a bis fatty acid lactone that was first isolated in 1982 from the roots of Uvaria accuminata. Uvaricin was the first in a class of compounds with potent anticancer activity known as acetogenins. Acetogenins, which are found in plants of the family Annonaceae, seem to kill cells by...
- Others
- Discodermolide
-Discodermolide is a recently discovered polyketide natural product found to be a potent inhibitor of tumor cell growth. The molecule's carbon skeleton is made up of eight polypropionate and four acetate units with 13 stereocenters.-History:...
- Aflatoxin
Aflatoxins are naturally occurring mycotoxins that are produced by many species of Aspergillus, a fungus, most notably Aspergillus flavus and Aspergillus parasiticus. Aflatoxins are toxic and among the most carcinogenic substances known...
Biosynthesis
Polyketides are synthesized by one or more specialized and highly complex
polyketide synthase- Background :Polyketide synthases, also known as PKSs, are a family of enzymes or enzyme complexes that produce polyketides, a large class of secondary metabolites, in bacteria, fungi, plants, and animals...
(PKS)
enzymeEnzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process are called substrates, and the enzyme converts them into different molecules, called the products. Almost all processes in a biological cell need enzymes to occur at...
s.