Elias James Corey is an American organic chemist. In 1990, he won the Nobel Prize in Chemistry "for his development of the theory and methodology of organic synthesis", specifically retrosynthetic analysis. Regarded by many as one of the greatest living chemists, he has developed numerous synthetic reagents, methodologies and total syntheses and has advanced the science of organic synthesis considerably.
Oxytetracycline is a broad-spectrum tetracycline antibiotic, the second of the group to be discovered.
Lovastatin, sold under the brand name Mevacor among others, is a statin medication, to treat high blood cholesterol and reduce the risk of cardiovascular disease. Its use is recommended together with lifestyle changes. It is taken by mouth.
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 against mycobacteria, and are therefore used to treat tuberculosis, leprosy, and mycobacterium avium complex (MAC) infections.
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, biosynthesis, and application of polyketides has evolved. It is a large and diverse group of secondary metabolites caused by its complex biosynthesis which resembles that of fatty acid synthesis. 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.
The Nicolaou Taxol total synthesis, published by K. C. Nicolaou and his group in 1994 concerns the total synthesis of taxol. Taxol is an important drug in the treatment of cancer but also expensive because the compound is harvested from a scarce resource, namely the pacific yew.
Ring-closing metathesis (RCM) is a widely used variation of olefin metathesis in organic chemistry for the synthesis of various unsaturated rings via the intramolecular metathesis of two terminal alkenes, which forms the cycloalkene as the E- or Z- isomers and volatile ethylene.
Doxorubicin (DXR) is a 14-hydroxylated version of daunorubicin, the immediate precursor of DXR in its biosynthetic pathway. Daunorubicin is more abundantly found as a natural product because it is produced by a number of different wild type strains of streptomyces. In contrast, only one known non-wild type species, streptomyces peucetius subspecies caesius ATCC 27952, was initially found to be capable of producing the more widely used doxorubicin. This strain was created by Arcamone et al. in 1969 by mutating a strain producing daunorubicin, but not DXR, at least in detectable quantities. Subsequently, Hutchinson's group showed that under special environmental conditions, or by the introduction of genetic modifications, other strains of streptomyces can produce doxorubicin. His group has also cloned many of the genes required for DXR production, although not all of them have been fully characterized. In 1996, Strohl's group discovered, isolated and characterized dox A, the gene encoding the enzyme that converts daunorubicin into DXR. By 1999, they produced recombinant Dox A, a Cytochrome P450 oxidase, and found that it catalyzes multiple steps in DXR biosynthesis, including steps leading to daunorubicin. This was significant because it became clear that all daunorubicin producing strains have the necessary genes to produce DXR, the much more therapeutically important of the two. Hutchinson's group went on to develop methods to improve the yield of DXR, from the fermentation process used in its commercial production, not only by introducing Dox A encoding plasmids, but also by introducing mutations to deactivate enzymes that shunt DXR precursors to less useful products, for example baumycin-like glycosides. Some triple mutants, that also over-expressed Dox A, were able to double the yield of DXR. This is of more than academic interest because at that time DXR cost about $1.37 million per kg and current production in 1999 was 225 kg per annum. More efficient production techniques have brought the price down to $1.1 million per kg for the non-liposomal formulation. Although DXR can be produced semi-synthetically from daunorubicin, the process involves electrophilic bromination and multiple steps and the yield is poor. Since daunorubicin is produced by fermentation, it would be ideal if the bacteria could complete DXR synthesis more effectively.
In enzymology, an erythronolide synthase is an enzyme that catalyzes the chemical reaction
Thiostrepton is a natural cyclic oligopeptide antibiotic of the thiopeptide class, derived from several strains of streptomycetes, such as Streptomyces azureus and Streptomyces laurentii. Thiostrepton is a natural product of the ribosomally synthesized and post-translationally modified peptide (RiPP) class.
Streptogramin A is a group of antibiotics within the larger family of antibiotics known as streptogramins. They are synthesized by the bacteria Streptomyces virginiae. The streptogramin family of antibiotics consists of two distinct groups: group A antibiotics contain a 23-membered unsaturated ring with lactone and peptide bonds while group B antibiotics are depsipeptides. While structurally different, these two groups of antibiotics act synergistically, providing greater antibiotic activity than the combined activity of the separate components. These antibiotics have until recently been commercially manufactured as feed additives in agriculture, although today there is increased interest in their ability to combat antibiotic-resistant bacteria, particularly vancomycin-resistant bacteria.
Macrophomic acid is a fungal metabolite isolated from the fungus Macrophoma commelinae. The enzyme macrophomate synthase converts 5-acetyl-4-methoxy-6-methyl-2-pyrone to 4-acetyl-3-methoxy-5-methyl-benzoic acid through an unusual intermolecular Diels-Alder reaction. The pathway to formation of macrophomic acid suggests that the enzyme is a natural Diels-Alderase. Formation of this type of aromatic ring compound normally proceeds via the shikimate and polyketide pathways; however, the production of macrophomic acid by macrophomate synthase proceeds totally differently. Learning about the production of macrophomic acid by a possible natural Diels-Alderase enzyme is important in understanding enzyme catalytic mechanisms. This knowledge can then be applied to organic synthesis.
Absinthin is a naturally produced triterpene lactone from the plant Artemisia absinthium (Wormwood). It constitutes one of the most bitter chemical agents responsible for absinthe's distinct taste. The compound shows biological activity and has shown promise as an anti-inflammatory agent, and should not to be confused with thujone, a neurotoxin also found in Artemisia absinthium.
Betaenone B, like other betaenones, is a secondary metabolite isolated from the fungus Pleospora betae, a plant pathogen. Its phytotoxic properties have been shown to cause sugar beet leaf spots, which is characterized by black, pycnidia containing, concentric circles eventually leading to necrosis of the leaf tissue. Of the seven phytotoxins isolated in fungal leaf spots from sugar beet, betaenone B showed the least amount of phytotoxicity showing only 8% inhibition of growth while betaenone A and C showed 73% and 89% growth inhibition, respectively. Betaenone B is therefore not considered toxic to the plant, but will produce leaf spots when present in high concentrations (0.33 μg/μL). While the mechanism of action of betaenone B has yet to be elucidated, betaenone C has been shown to inhibit RNA and protein synthesis. Most of the major work on betaenone B, including the initial structure elucidation of betaenone A, B and C as well as the partial elucidation mechanism of biosynthesis, was presented in three short papers published between 1983–88. The compounds were found to inhibit a variety of protein kinases signifying a possible role in cancer treatment.
Endiandric acid C, isolated from the tree Endiandra introrsa, is a well characterized chemical compound. Endiadric acid C is reported to have better antibiotic activity than ampicillin.
Callystatin A is a polyketide natural product from the leptomycin family of secondary metabolites. It was first isolated in 1997 from the marine sponge Callyspongia truncata which was collected from the Goto Islands in the Nagasaki Prefecture of Japan by the Kobayashi group. Since then its absolute configuration has been elucidated and callystatin A was discovered to have anti-fungal and anti-tumor activities with extreme potency against the human epidermoid carcinoma KB cells (IG50 = 10 pg/ml) and the mouse lymphocytic leukemia Ll210 cells (IG50 = 20 pg/ml).
Carbomycin, also known as magnamycin, is a colorless, optically active crystalline macrolide antibiotic with the molecular formula C42H67N O16. It is derived from the bacterium Streptomyces halstedii and active in inhibiting the growth of Gram-positive bacteria and "certain Mycoplasma strains." Its structure was first proposed by Robert Woodward in 1957 and was subsequently corrected in 1965.
Atrop-abyssomicin C is a polycyclic polyketide-type natural product that is the atropisomer of abyssomicin C. It is a spirotetronate that belongs to the class of tetronate antibiotics, which includes compounds such as tetronomycin, agglomerin, and chlorothricin. In 2006, the Nicolaou group discovered atrop-abyssomicin C while working on the total synthesis of abyssomicin C. Then in 2007, Süssmuth and co-workers isolated atrop-abyssomicin C from Verrucosispora maris AB-18-032, a marine actinomycete found in sediment of the Japanese sea. They found that atrop-abyssomicin C was the major metabolite produced by this strain, while abyssomicin C was a minor product. The molecule displays antibacterial activity by inhibiting the enzyme PabB, thereby depleting the biosynthesis of p-aminobenzoate.
Fostriecin is a type I polyketide synthase (PKS) derived natural product, originally isolated from the soil bacterium Streptomyces pulveraceus. It belongs to a class of natural products which characteristically contain a phosphate ester, an α,β-unsaturated lactam and a conjugated linear diene or triene chain produced by Streptomyces. This class includes structurally related compounds cytostatin and phoslactomycin. Fostriecin is a known potent and selective inhibitor of protein serine/threonine phosphatases, as well as DNA topoisomerase II. Due to its activity against protein phosphatases PP2A and PP4 which play a vital role in cell growth, cell division, and signal transduction, fostriecin was looked into for its antitumor activity in vivo and showed in vitro activity against leukemia, lung cancer, breast cancer, and ovarian cancer. This activity is thought to be due to PP2A's assumed role in regulating apoptosis of cells by activating cytotoxic T-lymphocytes and natural killer cells involved in tumor surveillance, along with human immunodeficiency virus-1 (HIV-1) transcription and replication.
Quinolidomicin A1 is a 60-membered macrocyclic compound isolated from Micromonospora sp. JY16. Quinolidomicins are a class of macrolides that contain a benzoquinone chromophore as well as an immense lactone ring, which far surpasses that in monozanomycin. It is currently the largest identified macrolide of terrestrial origin. It was initially discovered when in a screening for anti-tumor antibiotics, where it was found to be cytotoxic against P388 murine leukemia cells (IC50 8 nM), and has later been found to have strong cytotoxic activity against HT-29, MKN28, K562, and KB.
