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IUPAC name (1S,4R,4aR,14S,14aS,18Z)-6,8,11-trihydroxy-3-methoxy-1-methyl-7,12-dioxo-1,4,7,12,13,14-hexahydro-4a,14a-epoxy-4,14-hex[3]ene[1,5]diynonaphtho[2,3-c]phenanthridine-2-carboxylic acid | |
Other names (2R,4S,5S,8R,11Z,15S)-21,24,28-trihydroxy-7-methoxy-5-methyl-19,26-dioxo-3-oxa-16-azaheptacyclo[15.12.0.02,4.02,8.04,15.018,27.020,25]nonacosa-1(29),6,11,17,20,22,24,27-octaen-9,13-diyne-6-carboxylic acid | |
Identifiers | |
3D model (JSmol) | |
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Properties | |
C30H19NO9 | |
Molar mass | 537.473 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Dynemicin A is an anti-cancer enediyne drug. It displays properties which illustrate promise for cancer treatments, but still requires further research.
Dynemicin A was first isolated from the soil in the Gujarat State of India. It was discovered to be the natural product of the indigenous bacteria Micromonospora chersina . The natural product displays a bright purple color due to the anthraquinone chromophore structure within it. Initially, this compound was isolated for its aesthetic properties as a dye until further research demonstrated its anti-cancer properties. Shortly after the compound's discovery, the Bristol-Myers Pharmaceutical Company elucidated the structure in Japan using X-ray diffraction studies of triacetyldynemicin A; a closely related compound.
The first reported chemical synthesis of dynemicin was accomplished by Myers and coworkers. [1]
Dynemicin A is an antitumor natural product isolated from Micromonospora chersina which causes DNA strand cleavage. Iwasaki et al. first studied the biosynthetic pathway of Dynemicin A by 13C NMR labeling experiments. [2] Dynemicin A is thought to be biosynthesized separately from two different heptaketide chains originated from seven head-to-tail coupled acetate units, which is then connected to form Dynemicin A. Initially, precursors such as 3 and 4 were proposed to derive from the oleate/crepenynate pathway, as initially put forth for NSC Chrom A biosynthesis. [3] However, recent work by Thorson and coworkers revealed the biosynthesis of the dynemicin enediyne core to be catalyzed by an enediyne polyketide synthase (PKSE) similar to that employed in calicheamicin biosynthesis. [4] [5]
Dynemicin A is specific for B-DNA, and functions by intercalating into the minor groove of the double helix. For intercalation to occur, the separation between strands, which is usually 3-4 angstroms, needs to be widened to 7-8 angstroms to allow enough space for the ligand to bind. Given this, the DNA must be strained to accommodate the Dynemicin A, resulting in an induced fit-like process. Once intercalated within the DNA, the epoxide is activated in one of two ways. First, if NADPH or a thiol reduces the molecule the Bergman re-cyclization of the enediyne proceeds. Second, if a nucleophilic mechanism is utilized then the retro-Bergman re-cyclization of the enediyne is used. The final products of these two mechanisms are outlined below. When the re-cyclization occurs, the conformational changes and chemical reactions taking place result in an irreversible double stranded cleavage of the DNA, leading to cell death. During in vitro studies, the molecule showed an increased affinity for the specific 10 base pair sequence CTACTACTTG. However, in vivo studies have yet to confirm this phenomenon. Professor Martin Semmelhack of Princeton University was the first person to propose the NADPH reduction pathway.
The pharmacological properties of this drug have not yet been fully explored but currently suggest that it may be a more potent anti-cancer agent than other chemotherapeutic drugs. The bacterium is believed to use dynemicin A as an antibacterial agent to help it survive in its niche in the environment. Dynemicin A, as a drug, specifically targets B-DNA and is most effective in rapidly dividing cells. The broad spectrum of the drug prevents current use because it creates unwanted damage in normal healthy tissues. In vivo studies in mice and rats suggest that the treatment is most effective in leukemia, breast, and lung cancers. Synthetic alternatives which are more specific to cancer cells and leave healthy tissues unharmed are being researched. Other animal models are available, but have proven ineffective and therefore have no human trials currently underway. The enediyne property of this drug relates to another antibiotic known as neocarzinostatin which is approved for clinical use. As with dynemicin A, neocarzinostatin also interacts with DNA.
Doxorubicin, sold under the brand name Adriamycin among others, is a chemotherapy medication used to treat cancer. This includes breast cancer, bladder cancer, Kaposi's sarcoma, lymphoma, and acute lymphocytic leukemia. It is often used together with other chemotherapy agents. Doxorubicin is given by injection into a vein.
Mitoxantrone is an anthracenedione antineoplastic agent.
The Masamune-Bergman cyclization or Masamune-Bergman reaction or Masamune-Bergman cycloaromatization is an organic reaction and more specifically a rearrangement reaction taking place when an enediyne is heated in presence of a suitable hydrogen donor. It is the most famous and well-studied member of the general class of cycloaromatization reactions. It is named for Japanese-American chemist Satoru Masamune and American chemist Robert G. Bergman. The reaction product is a derivative of benzene.
Topoisomerase inhibitors are chemical compounds that block the action of topoisomerases, which are broken into two broad subtypes: type I topoisomerases (TopI) and type II topoisomerases (TopII). Topoisomerase plays important roles in cellular reproduction and DNA organization, as they mediate the cleavage of single and double stranded DNA to relax supercoils, untangle catenanes, and condense chromosomes in eukaryotic cells. Topoisomerase inhibitors influence these essential cellular processes. Some topoisomerase inhibitors prevent topoisomerases from performing DNA strand breaks while others, deemed topoisomerase poisons, associate with topoisomerase-DNA complexes and prevent the re-ligation step of the topoisomerase mechanism. These topoisomerase-DNA-inhibitor complexes are cytotoxic agents, as the un-repaired single- and double stranded DNA breaks they cause can lead to apoptosis and cell death. Because of this ability to induce apoptosis, topoisomerase inhibitors have gained interest as therapeutics against infectious and cancerous cells.
Neocarzinostatin (NCS) is a macromolecular chromoprotein enediyne antitumor antibiotic secreted by Streptomyces macromomyceticus.
The calicheamicins are a class of enediyne antitumor antibiotics derived from the bacterium Micromonospora echinospora, with calicheamicin γ1 being the most notable. It was isolated originally in the mid-1980s from the chalky soil, or "caliche pits", located in Kerrville, Texas. The sample was collected by a scientist working for Lederle Labs. It is extremely toxic to all cells and, in 2000, a CD33 antigen-targeted immunoconjugate N-acetyl dimethyl hydrazide calicheamicin was developed and marketed as targeted therapy against the non-solid tumor cancer acute myeloid leukemia (AML). A second calicheamicin-linked monoclonal antibody, inotuzumab ozogamicin an anti-CD22-directed antibody-drug conjugate, was approved by the U.S. Food and Drug Administration on August 17, 2017, for use in the treatment of adults with relapsed or refractory B-cell precursor acute lymphoblastic leukemia. Calicheamicin γ1 and the related enediyne esperamicin are the two of the most potent antitumor agents known.
Rebeccamycin (NSC 655649) is a weak topoisomerase I inhibitor isolated from Nocardia sp. It is structurally similar to staurosporine, but does not show any inhibitory activity against protein kinases. It shows significant antitumor properties in vitro (IC50=480nM against mouse B16 melanoma cells and IC50=500nM against P388 leukemia cells). It is an antineoplastic antibiotic and an intercalating agent.
Indolocarbazoles (ICZs) are a class of compounds that are under current study due to their potential as anti-cancer drugs and the prospective number of derivatives and uses found from the basic backbone alone. First isolated in 1977, a wide range of structures and derivatives have been found or developed throughout the world. Due to the extensive number of structures available, this review will focus on the more important groups here while covering their occurrence, biological activity, biosynthesis, and laboratory synthesis.
Enediynes are organic compounds containing two triple bonds and one double bond.
Echinomycin is a peptide antibiotic. It is a dimer of two peptides creating a cyclic structure. It contains a bicyclic aromatic chromophore that is attached to the dimerized cyclic peptide core and a thioacetal bridge. It intercalates into DNA at two specific sites, thereby blocking the binding of hypoxia inducible factor 1 alpha (HIF1alpha).
2-Amino-4-deoxychorismate dehydrogenase is an enzyme with systematic name (2S)-2-amino-4-deoxychorismate:FMN oxidoreductase. This enzyme catalyses the following chemical reaction
2-amino-4-deoxychorismate synthase is an enzyme with systematic name (2S)-2-amino-4-deoxychorismate:2-oxoglutarate aminotransferase. This enzyme catalyses the following chemical reaction
Free radical damage to DNA can occur as a result of exposure to ionizing radiation or to radiomimetic compounds. Damage to DNA as a result of free radical attack is called indirect DNA damage because the radicals formed can diffuse throughout the body and affect other organs. Malignant melanoma can be caused by indirect DNA damage because it is found in parts of the body not exposed to sunlight. DNA is vulnerable to radical attack because of the very labile hydrogens that can be abstracted and the prevalence of double bonds in the DNA bases that free radicals can easily add to.
Kedarcidin is a chromoprotein antitumor antibiotic first isolated from an Actinomycete in 1992, comprising an ansa-bridged enediyne chromophore (shown) as well as an apoprotein that serves to stabilize the toxin in the Actinomycete. Like other members of the enediyne class of drugs—so named for the nine-or-ten-membered core structure bearing an alkene directly attached to two alkynyl appendages—kedarcidin was likely evolved to kill bacteria that compete with the producing organism. Because it achieves this by causing DNA damage, however, kedarcidin is capable of harming tumor cells, as well. Kedarcidin is thus the subject of scientific research, both for its structural complexity as well as its anticancer properties.
Maduropeptin consists of a 1:1 complex of a carrier protein (MdpA) and a chromophore isolated from Actinomadura madurae. The chromophore has an enediyne structure and is an antibiotic with anticancer activity.
Ellipticine is an alkaloid first extracted from trees of the species Ochrosia elliptica and Rauvolfia sandwicensis, which inhibits the enzyme topoisomerase II via intercalative binding to DNA.
Thiocoraline is a microbial natural product of the depsipeptide class. Thiocoraline was isolated from the mycelium cake of a marine actinomycete strain L-13-ACM2-092. In vitro, thiocoraline causes an arrest in G1 phase of the cell cycle and decreases the rate of S phase progression towards G2/M phase. Thiocoraline is likely to be a DNA replication inhibitor. Thiocoraline is produced on a nonribosomal peptide synthetase (NRPS) assembly line.
C-1027 or Lidamycin is an antitumor antibiotic consisting of a complex of an enediyne chromophore and an apoprotein. It shows antibiotic activity against most Gram-positive bacteria. It is one of the most potent cytotoxic molecules known, due to its induction of a higher ratio of DNA double-strand breaks than single-strand breaks.
Shishijimicin A is an enediyne antibiotic isolated from Didemnum proliferum. Isolated in 2003 it is part of the family of 10 member ringed enediyne antitumor antibiotic agents, which includes: namenamicin, esperamicin and, calicheamicin. Due to its high potency from cytotoxicity, Shishjimicin A is currently undergoing testing as a possible Antibody-antibiotic Conjugate (ADCs) cancer treatment. Laboratory tests indicate it to be “more than 1,000 times as toxic to cancer cells as the anticancer drug taxol”, also known as Paclitaxel, a prevalent chemotherapy medication. As such, theoretically, only an administration of a minuscule dose of the molecule would be necessary per each treatment. As shishjimicin A supply is scarce and the full extent of its side effects is not yet established, there is still a need for further biological and clinical studies.
Bruceantin is a chemical compound that was first isolated from the plant Brucea antidysenterica in 1973. Chemically, it is classified as a secotriterpenoid and a quassinoid.
This article has an unclear citation style.(May 2011) |