Polyketides are a class of
natural product
A natural product is a natural compound or substance produced by a living organism—that is, found in nature. In the broadest sense, natural products include any substance produced by life. Natural products can also be prepared by chemical syn ...
s derived from a precursor molecule consisting of a chain of alternating
ketone
In organic chemistry, a ketone is a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double bo ...
(or
reduced forms of a ketone) and
methylene group
In organic chemistry, a methylene group is any part of a molecule that consists of two hydrogen atoms bound to a carbon atom, which is connected to the remainder of the molecule by two single bonds. The group may be represented as , where the '< ...
s: (-CO-CH
2-). First studied in the early 20th century, discovery, biosynthesis, and application of polyketides has evolved. It is a large and diverse group of
secondary metabolites
Secondary metabolites, also called specialised metabolites, toxins, secondary products, or natural products, are organic compounds produced by any lifeform, e.g. bacteria, fungi, animals, or plants, which are not directly involved in the nor ...
caused by its complex biosynthesis which resembles that of
fatty acid synthesis
In biochemistry, fatty acid synthesis is the creation of fatty acids from acetyl-CoA and NADPH through the action of enzymes called fatty acid synthases. This process takes place in the cytoplasm of the cell. Most of the acetyl-CoA which is conve ...
. Because of this diversity, polyketides can have various medicinal, agricultural, and industrial applications. Many polyketides are medicinal or exhibit acute toxicity. Biotechnology has enabled discovery of more naturally-occurring polyketides and evolution of new polyketides with novel or improved bioactivity.
History
Naturally produced polyketides by various plants and organisms have been used by humans since before studies on them began in the 19th and 20th century. In 1893,
J. Norman Collie
Professor John Norman Collie FRSE FRS (10 September 1859 – 1 November 1942), commonly referred to as J. Norman Collie, was an English scientist, mountaineer and explorer.
Life and work
He was born in Alderley Edge, Cheshire, the second of ...
synthesized detectable amounts of
orcinol
Orcinol is an organic compound with the formula CH3C6H3(OH)2. It occurs in many species of lichens including ''Roccella tinctoria'' and ''Lecanora''. Orcinol has been detected in the "toxic glue" of the ant species ''Camponotus saundersi''. It is ...
by heating
dehydracetic acid with barium hydroxide causing the pyrone ring to open into a triketide. Further studies in 1903 by Collie on the triketone polyketide intermediate noted the condensation occurring amongst compounds with multiple keten groups coining the term polyketides.
![Orsellinsäure_is](https://upload.wikimedia.org/wikipedia/commons/4/44/Orsellins%C3%A4ure_is.svg)
It wasn't until 1955 that the biosynthesis of polyketides were understood.
Arthur Birch used radioisotope labeling of carbon in acetate to trace the biosynthesis of
2-hydroxy-6-methylbenzoic acid in ''
Penicillium patulum
''Penicillium griseofulvum'' is a species of the genus of ''Penicillium'' which produces patulin, penifulvin A, cyclopiazonic acid, roquefortine C, shikimic acid, griseofulvin, and 6-Methylsalicylic acid (via a polyketide synthase
Polyketides ...
'' and demonstrate the head-to-tail linkage of acetic acids to form the polyketide. In the 1980s and 1990s, advancements in genetics allowed for isolation of the genes associated to polyketides to understand the biosynthesis.
Discovery
Polyketides can be produced in bacteria, fungi, plants, and certain marine organisms. Earlier discovery of naturally occurring polyketides involved the isolation of the compounds being produced by the specific organism using organic chemistry purification methods based on
bioactivity screens. Later technology allowed for the isolation of the genes and
heterologous expression Heterologous expression refers to the expression of a gene or part of a gene in a host organism that does not naturally have the gene or gene fragment in question. Insertion of the gene in the heterologous host is performed by recombinant DNA techno ...
of the genes to understand the biosynthesis. In addition, further advancements in biotechnology have allowed for the use of
metagenomics
Metagenomics is the study of genetic material recovered directly from environmental or clinical samples by a method called sequencing. The broad field may also be referred to as environmental genomics, ecogenomics, community genomics or microb ...
and
genome mining
Genome mining describes the exploitation of genomic information for the discovery of biosynthetic pathways of natural products and their possible interactions. It depends on computational technology and bioinformatics tools. The mining process reli ...
to find new polyketides using similar enzymes to known polyketides.
Biosynthesis
Polyketides are synthesized by multienzyme polypeptides that resemble eukaryotic fatty acid synthase but are often much larger.
They include acyl-carrier domains plus an assortment of enzymatic units that can function in an iterative fashion, repeating the same elongation/modification steps (as in fatty acid synthesis), or in a sequential fashion so as to generate more heterogeneous types of polyketides.
Polyketide Synthase (PKS)
Polyketides are produced by
polyketide synthase
Polyketides are a class of natural products derived from a precursor molecule consisting of a chain of alternating ketone (or reduced forms of a ketone) and methylene groups: (-CO-CH2-). First studied in the early 20th century, discovery, biosynth ...
s. The core biosynthesis involves stepwise condensation of a starter unit (typically
acetyl-CoA
Acetyl-CoA (acetyl coenzyme A) is a molecule that participates in many biochemical reactions in protein, carbohydrate and lipid metabolism. Its main function is to deliver the acetyl group to the citric acid cycle (Krebs cycle) to be oxidized for ...
or
propionyl-CoA
Propionyl-CoA is a coenzyme A derivative of propionic acid. It is composed of a 24 total carbon chain (without the coenzyme, it is a 3 carbon structure) and its production and metabolic fate depend on which organism it is present in. Several diffe ...
) with an extender unit (either
malonyl-CoA
Malonyl-CoA is a coenzyme A derivative of malonic acid.
Functions
It plays a key role in chain elongation in fatty acid biosynthesis and polyketide biosynthesis.
Fatty acid biosynthesis
Malonyl-CoA provides 2-carbon units to fatty acids and commi ...
or methylmalonyl-CoA). The condensation reaction is accompanied by the decarboxylation of the extender unit, yielding a beta-keto functional group and releasing a carbon dioxide.
The first condensation yields an acetoacetyl group, a diketide. Subsequent condensations yield triketides, tetraketide, etc. Other starter units attached to a
coezyme A include
isobutyrate,
cyclohexanecarboxylate
Cyclohexanecarboxylic acid is the organic compound with the formula C6H11CO2H. It is the carboxylic acid of cyclohexane. It is a colorless oil that crystallizes near room temperature..
Preparation and reactions
It is prepared by hydrogenation of ...
,
malonate
The conjugate acids are in :Carboxylic acids.
{{Commons category, Carboxylate ions, Carboxylate anions
Carbon compounds
Oxyanions ...
, and
benzoate
Benzoic acid is a white (or colorless) solid organic compound with the formula , whose structure consists of a benzene ring () with a carboxyl () substituent. It is the simplest aromatic carboxylic acid. The name is derived from gum benzoin, wh ...
.
PKSs are multi-domain enzymes or enzyme complex consisting of various domains. The polyketide chains produced by a minimal
polyketide synthase
Polyketides are a class of natural products derived from a precursor molecule consisting of a chain of alternating ketone (or reduced forms of a ketone) and methylene groups: (-CO-CH2-). First studied in the early 20th century, discovery, biosynth ...
(consisting of a
acyltransferase
Acyltransferase is a type of transferase enzyme that acts upon acyl groups.
Examples include:
* Glyceronephosphate O-acyltransferase
* Lecithin-cholesterol acyltransferase
*Long-chain-alcohol O-fatty-acyltransferase
In enzymology, a long-chain- ...
and
ketosynthase Ketoacyl synthases (KSs) catalyze the condensation reaction of acyl-CoA or acyl-acyl ACP with malonyl-CoA to form 3-ketoacyl-CoA or with malonyl-ACP to form 3-ketoacyl-ACP. This reaction is a key step in the fatty acid synthesis cycle, as the result ...
for the stepwise condensation of the starter unit and extender units) are almost invariably modified. Each polyketide synthases is unique to each polyketide chain because they contain different combinations of domains that reduce the carbonyl group to a hydroxyl (via a
ketoreductase), an olefin (via a
dehydratase Dehydratases are a group of lyase enzymes that form double and triple bonds in a substrate through the removal of water. They can be found in many places including the mitochondria, peroxisome and cytosol. There are more than 150 different dehydra ...
), or a methylene (via an
enoylreductase).
Termination of the polyketide scaffold biosynthesis can also vary. It is sometimes accompanied by a
thioesterase
Thioesterases are enzymes which belong to the esterase family. Esterases, in turn, are one type of the several hydrolases known.
Thioesterases exhibit esterase activity (splitting of an ester into acid and Alcohol (chemistry), alcohol, in the pres ...
that releases the polyketide via hydrating the thioester linkage (as in fatty acid synthesis) creating a linear polyketide scaffold. However, if water is not able to reach the active site, the hydrating reaction will not occur and an intramolecular reaction is more probable creating a macrocyclic polyketide. Another possibility is spontaneous hydrolysis without the aid of a thioesterase.
Post-tailoring enzymes
Further possible modifications to the polyketide scaffolds can be made. This can include glycosylation via a
glucosyltransferase Glucosyltransferases are a type of glycosyltransferase that enable the transfer of glucose.
Examples include:
* glycogen synthase
* glycogen phosphorylase
Glycogen phosphorylase is one of the phosphorylase enzymes (). Glycogen phosphorylase cat ...
or oxidation via a
monooxygenase
Monooxygenases are enzymes that incorporate one hydroxyl group (−OH) into substrates in many metabolic pathways. In this reaction, the two atoms of dioxygen are reduced to one hydroxyl group and one H2O molecule by the concomitant oxidation o ...
. Similarly, cyclization and aromatization can be introduced via a
cyclase A cyclase is an enzyme, almost always a lyase, that catalyzes a chemical reaction to form a cyclic compound. Important cyclase enzymes include:
* Adenylyl cyclase, which forms cyclic AMP from adenosine triphosphate (EC 4.6.1.1)
** ADCY1
** ADCY2 ...
, sometimes proceeded by the enol tautomers of the polyketide.
These enzymes are not part of the domains of the polyketide synthase. Instead, they are found in
gene cluster
A gene family is a set of homologous genes within one organism. A gene cluster is a group of two or more genes found within an organism's DNA that encode similar polypeptides, or proteins, which collectively share a generalized function and are o ...
s in the genome close to the polyketide synthase genes.
Classification
Polyketides are structurally diverse family. There are various subclasses of polyketides including:
aromatics
Aromatic compounds, also known as "mono- and polycyclic aromatic hydrocarbons", are organic compounds containing one or more aromatic rings. The parent member of aromatic compounds is benzene. The word "aromatic" originates from the past grouping ...
, macrolactones/
macrolide
The Macrolides are a class of natural products that consist of 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. Macrol ...
s,
decalin
Decalin (decahydronaphthalene, also known as bicyclo .4.0ecane and sometimes decaline), a bicyclic organic compound, is an industrial solvent. A colorless liquid with an aromatic odor, it is used as a solvent for many resins or fuel additives.
I ...
ring containing,
polyether
In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups. They have the general formula , where R and R′ represent the alkyl or aryl groups. Ethers can again be c ...
, and
polyene
In organic chemistry, polyenes are poly- unsaturated, organic compounds that contain at least three alternating double () and single () carbon–carbon bonds. These carbon–carbon double bonds interact in a process known as conjugation, resultin ...
s.
Polyketide synthases are also broadly divided into three classes: Type I PKS (multimodular megasynthases that are non-iterative, often producing macrocodes, polyethers, and polyenes), Type II PKS (dissociated
enzymes
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different molecule ...
with iterative action, often producing aromatics), and Type III PKS (
chalcone synthase-like PKSs, producing small aromatic molecules).
In addition to these subclasses, there also exist polyketides that are hybridized with
nonribosomal peptide Nonribosomal peptides (NRP) are a class of peptide secondary metabolites, usually produced by microorganisms like bacteria and fungi. Nonribosomal peptides are also found in higher organisms, such as nudibranchs, but are thought to be made by bacter ...
s (Hybrid NRP-PK and PK-NRP). Since nonribosomal peptide assembly lines use carrier proteins similar to those use in polyketide synthases, convergence of the two systems evolved to form hybrids, resulting in polypeptides with nitrogen in the skeletal structure and complex function groups similar to those found in amino acids.
Applications
Polyketide
antibiotic
An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention of ...
s,
antifungals
An antifungal medication, also known as an antimycotic medication, is a pharmaceutical fungicide or fungistatic used to treat and prevent mycosis such as athlete's foot, ringworm, candidiasis (thrush), serious systemic infections such as crypto ...
,
cytostatic
Cytostasis (cyto – cell; stasis – stoppage) is the inhibition of cell growth and multiplication. Cytostatic refers to a cellular component or medicine that inhibits cell division.
Cytostasis is an important prerequisite for structured multic ...
s,
anticholesteremic,
antiparasitics
Antiparasitics are a class of medications which are indicated for the treatment of parasitic diseases, such as those caused by helminths, amoeba, ectoparasites, parasitic fungi, and protozoa, among others. Antiparasitics target the parasitic agents ...
,
coccidiostat
A coccidiostat is an antiprotozoal agent that acts upon Coccidia parasites.
Examples include:
* Amprolium
* Arprinocid
* Artemether
* Clazuril
* Clopidol
* Decoquinate
* Diclazuril
* Dinitolmide
* Ethopabate
* Halofuginone
* Lasalocid
* Monens ...
s,
animal growth promoters and natural
insecticide
Insecticides are substances used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. Insecticides are used in agriculture, medicine, industry and by consumers. Insecticides are claimed to b ...
s are in commercial use.
Medicinal
There are more than 10,000 known polyketides, 1% of which are known to have potential for drug activity. Polyketides comprise 20% of the top-selling pharmaceuticals with combined worldwide revenues of over USD 18 billion per year.
Examples
*
Macrolide
The Macrolides are a class of natural products that consist of 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. Macrol ...
s
**
Pikromycin
Pikromycin was studied by Brokmann and Hekel in 1951 and was the first antibiotic macrolide to be isolated.
Pikromycin is synthesized through a type I polyketide synthase system in ''Streptomyces venezuelae'', a species of Gram-positive bacterium ...
, the first isolated macrolide (1951)
** The
antibiotic
An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention of ...
s
erythromycin A
Erythromycin is an antibiotic used for the treatment of a number of bacterial infections. This includes respiratory tract infections, skin infections, chlamydia infections, pelvic inflammatory disease, and syphilis. It may also be used duri ...
,
clarithromycin
Clarithromycin, sold under the brand name Biaxin among others, is an antibiotic used to treat various bacterial infections. This includes strep throat, pneumonia, skin infections, ''H. pylori'' infection, and Lyme disease, among others. Clarith ...
, and
azithromycin
Azithromycin, sold under the brand names Zithromax (in oral form) and Azasite (as an eye drop), is an antibiotic medication used for the treatment of a number of bacterial infections. This includes middle ear infections, strep throat, pneumon ...
** The
antihelminthic
Anthelmintics or antihelminthics are a group of antiparasitic drugs that expel parasitic worms (helminths) and other internal parasites from the body by either stunning or killing them and without causing significant damage to the host. They may a ...
s
ivermectin
Ivermectin (, '' EYE-vər-MEK-tin'') is an antiparasitic drug. After its discovery in 1975, its first uses were in veterinary medicine to prevent and treat heartworm and acariasis. Approved for human use in 1987, today it is used to treat inf ...
**
*
Ansamycin
Ansamycins is a family of bacterial secondary metabolites that show antimicrobial activity against many Gram-positive and some Gram-negative bacteria, and includes various compounds, including streptovaricins and rifamycins. In addition, these ...
s
** The
antitumor
Cancer can be treated by surgery, chemotherapy, radiation therapy, hormonal therapy, targeted therapy (including immunotherapy such as monoclonal antibody therapy) and synthetic lethality, most commonly as a series of separate treatments (e.g. ...
agents
geldanamycin
Geldanamycin is a 1,4-benzoquinone ansamycin antitumor antibiotic that inhibits the function of Hsp90 (Heat Shock Protein 90) by binding to the unusual ADP/ATP-binding pocket of the protein. HSP90 client proteins play important roles in the regulat ...
and
macbecin
Macbecin belongs to the ansamycin family of antibiotics and was first isolated from actinomycete bacteria. Macbecin possesses potent antitumor properties. In-vitro studies have shown that Macbecin is effective in the eradication of Gram-positive ...
,
** The
antibiotic
An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention of ...
rifamycin
The rifamycins are a group of antibiotics that are synthesized either naturally by the bacterium ''Amycolatopsis rifamycinica'' or artificially. They are a subclass of the larger family of ansamycins. Rifamycins are particularly effective again ...
*
Polyene
In organic chemistry, polyenes are poly- unsaturated, organic compounds that contain at least three alternating double () and single () carbon–carbon bonds. These carbon–carbon double bonds interact in a process known as conjugation, resultin ...
s
** The
antifungals
An antifungal medication, also known as an antimycotic medication, is a pharmaceutical fungicide or fungistatic used to treat and prevent mycosis such as athlete's foot, ringworm, candidiasis (thrush), serious systemic infections such as crypto ...
amphotericin
Amphotericin B is an antifungal medication used for serious mycosis, fungal infections and leishmaniasis. The fungal infections it is used to treat include mucormycosis, aspergillosis, blastomycosis, candida infections, candidiasis, coccidioidomy ...
,
nystatin
Nystatin, sold under the brandname Mycostatin among others, is an antifungal medication. It is used to treat '' Candida'' infections of the skin including diaper rash, thrush, esophageal candidiasis, and vaginal yeast infections. It may also be ...
and
pimaricin
Natamycin, also known as pimaricin, is an antifungal medication used to treat fungal infections around the eye. This includes infections of the eyelids, conjunctiva, and cornea. It is used as eyedrops. Natamycin is also used in the food industr ...
*
Polyether
In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups. They have the general formula , where R and R′ represent the alkyl or aryl groups. Ethers can again be c ...
s
** The
antibiotic
An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention of ...
monensin
Monensin is a polyether antibiotic isolated from ''Streptomyces cinnamonensis''. It is widely used in ruminant animal feeds.
The structure of monensin was first described by Agtarap et al. in 1967, and was the first polyether antibiotic to have i ...
*
Tetracycline
Tetracycline, sold under various brand names, is an oral antibiotic in the tetracyclines family of medications, used to treat a number of infections, including Acne vulgaris, acne, cholera, brucellosis, plague (disease), plague, malaria, and sy ...
s
**The antibiotic agent
doxycycline
Doxycycline is a broad-spectrum tetracycline class antibiotic used in the treatment of infections caused by bacteria and certain parasites. It is used to treat bacterial pneumonia, acne, chlamydia infections, Lyme disease, cholera, typhus, an ...
*
Acetogenin
Acetogenins are a class of polyketide natural products found in plants of the family Annonaceae. They are characterized by linear 32- or 34-carbon chains containing oxygenated functional groups including hydroxyls, ketones, epoxides, tetrahydrof ...
s
**
bullatacin
Bullatacin is a bis(tetrahydrofuranoid) fatty acid lactone found in some fruits from Annonaceae family. It is a member of the class of compounds known as acetogenin
Acetogenins are a class of polyketide natural products found in plants of the f ...
**
squamocin
**
molvizarin
Molvizarin is a cytotoxic acetogenin derivate with the molecular formula C35H62O7 which has been isolated from the bark of the plant '' Annona cherimolia''. Molvizarin has ''in vitro
''In vitro'' (meaning in glass, or ''in the glass'') studi ...
**
uvaricin
Uvaricin is a bis(tetrahydrofuranoid) fatty acid lactone that was first isolated in 1982 from the roots of the Annonaceae ''Uvaria acuminata''. Uvaricin was the first known example in a class of compounds known as acetogenins. Acetogenins, which ar ...
**
annonacin
Annonacin is a chemical compound with toxic effects, especially in the nervous system, found in some fruits such as the paw paw, custard apples, soursop, and others from the family ''Annonaceae''. It is a member of the class of compounds known ...
* Others
** The
immunosuppressant
Immunosuppressive drugs, also known as immunosuppressive agents, immunosuppressants and antirejection medications, are drugs that inhibit or prevent activity of the immune system.
Classification
Immunosuppressive drugs can be classified in ...
s
tacrolimus (FK506) (a
calcineurin
Calcineurin (CaN) is a calcium and calmodulin dependent serine/threonine protein phosphatase (also known as protein phosphatase 3, and calcium-dependent serine-threonine phosphatase). It activates the T cells of the immune system and can be bloc ...
inhibitor) and
sirolimus
Sirolimus, also known as rapamycin and sold under the brand name Rapamune among others, is a macrolide compound that is used to coat coronary stents, prevent organ transplant rejection, treat a rare lung disease called lymphangioleiomyomatosis, ...
(rapamycin) (a
mTOR
The mammalian target of sirolimus, rapamycin (mTOR), also referred to as the mechanistic target of rapamycin, and sometimes called FK506-binding protein 12-rapamycin-associated protein 1 (FRAP1), is a kinase that in humans is encoded by the ''MT ...
inhibitor)
**
Radicicol
Radicicol, also known as monorden, is a natural product that binds to Hsp90 (Heat Shock Protein 90) and alters its function. HSP90 client proteins play important roles in the regulation of the cell cycle, cell growth, cell survival, apoptosis, ang ...
and the pochonin family (
HSP90
Hsp90 (heat shock protein 90) is a chaperone protein that assists other proteins to fold properly, stabilizes proteins against heat stress, and aids in protein degradation. It also stabilizes a number of proteins required for tumor growth, ...
inhibitors)
**The
cholesterol
Cholesterol is any of a class of certain organic molecules called lipids. It is a sterol (or modified steroid), a type of lipid. Cholesterol is biosynthesized by all animal cells and is an essential structural component of animal cell mem ...
lowering agent
lovastatin
Lovastatin, sold under the brand name Mevacor among others, is a statin medication, to treat hypercholesterolemia, high blood cholesterol and reduce the risk of cardiovascular disease. Its use is recommended together with lifestyle changes. It ...
**
Discodermolide
(+)-Discodermolide is a polyketide natural product found to stabilize microtubules. (+)-discodermolide was isolated by Gunasekera and his co-workers at the Harbor Branch Oceanographic Institute from the deep-sea sponge ''Discodermia dissoluta'' in ...
**
Aflatoxin
Aflatoxins are various poisonous carcinogens and mutagens that are produced by certain molds, particularly ''Aspergillus'' species. The fungi grow in soil, decaying vegetation and various staple foodstuffs and commodities such as hay, sweetcorn ...
**
Usnic acid
Usnic acid is a naturally occurring dibenzofuran derivative found in several lichen species with the formula C18H16O7. It was first isolated by German scientist W. Knop in 1844 and first synthesized between 1933-1937 by Curd and Robertson. Usnic a ...
**
Anthracimycin
**
Anthramycin
**
Olivetolic acid
Olivetolic acid is an organic compound that is an intermediate in the biosynthetic pathway of the cannabinoids in ''Cannabis sativa
''Cannabis sativa'' is an annual herbaceous flowering plant indigenous to Eastern Asia, but now of cosmopoli ...
(intermediate in
cannabinoid
Cannabinoids () are several structural classes of compounds found in the cannabis plant primarily and most animal organisms (although insects lack such receptors) or as synthetic compounds. The most notable cannabinoid is the phytocannabinoid tet ...
pathways)
Agricultural
Polyketides can be used for crop protection as
pesticide
Pesticides are substances that are meant to control pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microbicide, fungicide, and lampri ...
s.
Examples
* Pesticides
**
spinosad
Spinosad is an insecticide based on chemical compounds found in the bacterial species ''Saccharopolyspora spinosa''. The genus ''Saccharopolyspora'' was discovered in 1985 in isolates from crushed sugarcane. The bacteria produce yellowish-pink ae ...
or spinosyn (an
insecticide
Insecticides are substances used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. Insecticides are used in agriculture, medicine, industry and by consumers. Insecticides are claimed to b ...
)
**
avermectin
The avermectins are a series of drugs and pesticides used to treat parasitic worms and insect pests. They are a group of 16-membered macrocyclic lactone derivatives with potent anthelmintic and insecticidal properties. These naturally occurring co ...
** polynactins
** tetramycin
Industrial
Polyketides can be used for industrial purposes, such as pigmentation and dietary flavonoids.
Examples
* Pigments
** azaphilones
**
hydroxyanthraquinone A hydroxyanthraquinone (formula: C14H9O2(OH)) is any of several organic compounds that can be viewed as derivatives of an anthraquinone through replacement of one hydrogen atom (H) by a hydroxyl group (-OH).
The IUPAC nomenclature recommends hydrox ...
s
**
naphthoquinone
Naphthoquinones constitute a class of organic compounds structurally related to naphthalene. Two isomers are common for the parent naphthoquinones:
* 1,2-Naphthoquinone
* 1,4-Naphthoquinone
Natural products
* Alkannin
* Hexahydroxy-1,4-napht ...
s
* Flavonoids
**
curcumin
Curcumin is a bright yellow chemical produced by plants of the ''Curcuma longa'' species. It is the principal curcuminoid of turmeric (''Curcuma longa''), a member of the ginger family, Zingiberaceae. It is sold as a herbal supplement, cosmetic ...
**
silymarin
Silibinin (International Nonproprietary Name, INN), also known as silybin (both from ''Silybum'', the Genus–differentia definition, generic name of the plant from which it is extracted), is the major active constituent of silymarin, a standard ...
**
daidzein
Daidzein (7-hydroxy-3-(4-hydroxyphenyl)-4H-chromen-4-one) is a naturally occurring compound found exclusively in soybeans and other legumes and structurally belongs to a class of compounds known as isoflavones. Daidzein and other isoflavones a ...
Biotechnology
Protein engineering
Protein engineering is the process of developing useful or valuable proteins. It is a young discipline, with much research taking place into the understanding of protein folding and recognition for protein design principles. It has been used to imp ...
has opened avenues for creating polyketides not found in nature. For example, the modular nature of PKSs allows for domains to be replaced, added or deleted. Introducing diversity in assembly lines enables the discovery of new polyketides with increased bioactivity or new bioactivity.
Furthermore, the use of
genome mining
Genome mining describes the exploitation of genomic information for the discovery of biosynthetic pathways of natural products and their possible interactions. It depends on computational technology and bioinformatics tools. The mining process reli ...
allows for discovery of new natural polyketides and their assembly lines.
See also
*
Esterase
An esterase is a hydrolase enzyme that splits esters into an acid and an alcohol in a chemical reaction with water called hydrolysis.
A wide range of different esterases exist that differ in their substrate specificity, their protein structure, ...
*
Nonribosomal peptide Nonribosomal peptides (NRP) are a class of peptide secondary metabolites, usually produced by microorganisms like bacteria and fungi. Nonribosomal peptides are also found in higher organisms, such as nudibranchs, but are thought to be made by bacter ...
*
ThYme (database) (2010)
References
{{reflist
NADH dehydrogenase inhibitors
Plant toxin insecticides