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Combretastatins
Combretastatin is a dihydrostilbenoid found in ''Combretum caffrum''. As a class Combretastatins are a class of natural phenols. A variety of different natural combretastatin molecules are present in the bark of ''Combretum caffrum'', commonly known as South African Bush Willow. Despite having a similar name, combretastatins are unrelated to statins, a family of cholesterol lowering drugs. Natural combretastatins Molecules that fall into the combretastatin family generally share 3 common structural features: a trimethoxy "A"-ring, a "B"-ring containing substituents often at C3' and C4', and ftenan ethene bridge between the two rings which provides necessary structural rigidity. Molecules with such an ethene bridge are also stilbenoids, molecules with a non-ethene bridge are dihydrostilbenoids. Molecules with C3' amino and hydroxyl substituents are very active, and molecules with C4' hydroxyl or methoxy substituents are also cytotoxic. Of the natural products presently known ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Combretastatin A-4
Combretastatin A-4 is a combretastatin and a stilbenoid. It can be isolated from '' Combretum caffrum'', the Eastern Cape South African bushwillow tree or in '' Combretum leprosum'', the mofumbo, a species found in Brazil. Function Tubulin represents a potent target in cancer chemotherapy, given its role in cell division. Combretastatin is a naturally occurring well known tubulin polymerization inhibitor. Combretastatin A-4 comes in two stereoisomers (cis (shown top right), and trans); The cis form binds much better to the 'colchicine' site on tubulin to inhibit polymerization. Derivatives Combretastatin A-4 is the active component of combretastatin A-4 phosphate, a prodrug designed to damage the vasculature (blood vessels) of cancer tumors causing central necrosis. A large number of synthetic derivatives have been reported, including beta-lactam A beta-lactam (β-lactam) ring is a four-membered lactam. A ''lactam'' is a cyclic amide, and ''beta''-lactams are named so be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Combretastatin B-1
Combretastatin B-1 is a combretastatin and a dihydrostilbenoid Dihydrostilbenoids (bibenzyls) are natural phenols formed from the dihydrostilbene ( bibenzyl) backbone. Examples Dihydro-resveratrol is a natural phenol with a bibenzyl structure found in wine. It is also a metabolite of trans-resveratrol for .... It can be found in '' Combretum caffrum'', the Eastern Cape South African bushwillow tree or in '' Combretum kraussii'', the forest bushwillow.Uteroactive constituents from Combretum kraussii. Bridget K Brookes, Olga V Doudoukina, Lynn C Katsoulis and Joy H D Veale, South African Journal of Chemistry, Dec 99, Vol. 52, Issue 4, page 127abstract It can be produced by selective hydrogenation of Combretastatin A-1. It is a potent inhibitor of microtubule assembly in vitro. References Combretastatins Dihydrostilbenoids {{aromatic-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Combretastatin A-4
Combretastatin A-4 is a combretastatin and a stilbenoid. It can be isolated from '' Combretum caffrum'', the Eastern Cape South African bushwillow tree or in '' Combretum leprosum'', the mofumbo, a species found in Brazil. Function Tubulin represents a potent target in cancer chemotherapy, given its role in cell division. Combretastatin is a naturally occurring well known tubulin polymerization inhibitor. Combretastatin A-4 comes in two stereoisomers (cis (shown top right), and trans); The cis form binds much better to the 'colchicine' site on tubulin to inhibit polymerization. Derivatives Combretastatin A-4 is the active component of combretastatin A-4 phosphate, a prodrug designed to damage the vasculature (blood vessels) of cancer tumors causing central necrosis. A large number of synthetic derivatives have been reported, including beta-lactam A beta-lactam (β-lactam) ring is a four-membered lactam. A ''lactam'' is a cyclic amide, and ''beta''-lactams are named so be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Combretastatin A-1
Combretastatin A-1 is a combretastatin and a stilbenoid. It can be found in '' Combretum caffrum'', the Eastern Cape South African Bushwillow tree. Biological effects in mammals It is an antiangiogenic agent acting by destabilizing tubulin, which induces cell apoptosis of proliferating endothelial cells. Derivatives as drugs Currently designated an orphan drug by the FDA, combretastatin A1 diphosphate (OXi4503 or CA1P) is in Phase I clinical trials for relapsed and refractory acute myeloid leukemia and myelodysplastic syndrome A myelodysplastic syndrome (MDS) is one of a group of cancers in which immature blood cells in the bone marrow do not mature, and as a result, do not develop into healthy blood cells. Early on, no symptoms typically are seen. Later, symptoms may .... References Combretastatins Stilbenoids {{Aromatic-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dihydrostilbenoid
Dihydrostilbenoids (bibenzyls) are natural phenols formed from the dihydrostilbene ( bibenzyl) backbone. Examples Dihydro-resveratrol is a natural phenol with a bibenzyl structure found in wine. It is also a metabolite of trans-resveratrol formed in the intestine by the hydrogenation of the double bond by microflora. Combretastatin and combretastatin B-1 are two dihydrostilbenoids found in ''Combretum caffrum'', an African tree. Isonotholaenic acid is another dihydrostilbenoid found in the Andean fern '' Argyrochosma nivea''. Bibenzyls ( 3,4'-dihydroxy-5,5'-dimethoxybibenzyl, 3,3'-dihydroxy-5-methoxybibenzyl ( batatasin III)) can be found in the orchid '' Bulbophyllum vaginatum''. Bis(bibenzyls) and macrocyclic bis(benzyls) can be found in bryophytes, such as the compounds plagiochin E, 13,13'-O-isoproylidenericcardin D, riccardin H, marchantin E, neomarchantin A, marchantin A and marchantin B in the Chinese liverwort ''Marchantia polymorpha''. Prenylated bibenzyls c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microtubules
Microtubules are polymers of tubulin that form part of the cytoskeleton and provide structure and shape to eukaryotic cells. Microtubules can be as long as 50 micrometres, as wide as 23 to 27 nm and have an inner diameter between 11 and 15 nm. They are formed by the polymerization of a dimer of two globular proteins, alpha and beta tubulin into protofilaments that can then associate laterally to form a hollow tube, the microtubule. The most common form of a microtubule consists of 13 protofilaments in the tubular arrangement. Microtubules play an important role in a number of cellular processes. They are involved in maintaining the structure of the cell and, together with microfilaments and intermediate filaments, they form the cytoskeleton. They also make up the internal structure of cilia and flagella. They provide platforms for intracellular transport and are involved in a variety of cellular processes, including the movement of secretory vesicles, organell ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytoskeleton
The cytoskeleton is a complex, dynamic network of interlinking protein filaments present in the cytoplasm of all cells, including those of bacteria and archaea. In eukaryotes, it extends from the cell nucleus to the cell membrane and is composed of similar proteins in the various organisms. It is composed of three main components, microfilaments, intermediate filaments and microtubules, and these are all capable of rapid growth or disassembly dependent on the cell's requirements. A multitude of functions can be performed by the cytoskeleton. Its primary function is to give the cell its shape and mechanical resistance to deformation, and through association with extracellular connective tissue and other cells it stabilizes entire tissues. The cytoskeleton can also contract, thereby deforming the cell and the cell's environment and allowing cells to migrate. Moreover, it is involved in many cell signaling pathways and in the uptake of extracellular material ( endocytosis), the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mitotic Spindle
In cell biology, the spindle apparatus refers to the cytoskeletal structure of eukaryotic cells that forms during cell division to separate sister chromatids between daughter cells. It is referred to as the mitotic spindle during mitosis, a process that produces genetically identical daughter cells, or the meiotic spindle during meiosis, a process that produces gametes with half the number of chromosomes of the parent cell. Besides chromosomes, the spindle apparatus is composed of hundreds of proteins. Microtubules comprise the most abundant components of the machinery. Spindle structure Attachment of microtubules to chromosomes is mediated by kinetochores, which actively monitor spindle formation and prevent premature anaphase onset. Microtubule polymerization and depolymerization dynamic drive chromosome congression. Depolymerization of microtubules generates tension at kinetochores; bipolar attachment of sister kinetochores to microtubules emanating from opposite cell pol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endothelial Cells
The endothelium is a single layer of squamous endothelial cells that line the interior surface of blood vessels and lymphatic vessels. The endothelium forms an interface between circulating blood or lymph in the lumen and the rest of the vessel wall. Endothelial cells form the barrier between vessels and tissue and control the flow of substances and fluid into and out of a tissue. Endothelial cells in direct contact with blood are called vascular endothelial cells whereas those in direct contact with lymph are known as lymphatic endothelial cells. Vascular endothelial cells line the entire circulatory system, from the heart to the smallest capillaries. These cells have unique functions that include fluid filtration, such as in the glomerulus of the kidney, blood vessel tone, hemostasis, neutrophil recruitment, and hormone trafficking. Endothelium of the interior surfaces of the heart chambers is called endocardium. An impaired function can lead to serious health issues throug ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cellular Division
Cell division is the process by which a parent cell divides into two daughter cells. Cell division usually occurs as part of a larger cell cycle in which the cell grows and replicates its chromosome(s) before dividing. In eukaryotes, there are two distinct types of cell division: a vegetative division (mitosis), producing daughter cells genetically identical to the parent cell, and a cell division that produces haploid gametes for sexual reproduction (meiosis), reducing the number of chromosomes from two of each type in the diploid parent cell to one of each type in the daughter cells. In cell biology, mitosis ( /maɪˈtoʊsɪs/) is a part of the cell cycle, in which, replicated chromosomes are separated into two new nuclei. Cell division gives rise to genetically identical cells in which the total number of chromosomes is maintained. In general, mitosis (division of the nucleus) is preceded by the S stage of interphase (during which the DNA replication occurs) and is often fol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polymerization
In polymer chemistry, polymerization (American English), or polymerisation (British English), is a process of reacting monomer, monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks. There are many forms of polymerization and different systems exist to categorize them. In chemical compounds, polymerization can occur via a variety of reaction mechanisms that vary in complexity due to the functional groups present in the reactants and their inherent steric effects. In more straightforward polymerizations, alkenes form polymers through relatively simple free-radical reaction, radical reactions; in contrast, reactions involving substitution at a carbonyl group require more complex synthesis due to the way in which reactants polymerize. Alkanes can also be polymerized, but only with the help of strong acids. As alkenes can polymerize in somewhat straightforward radical reactions, they form useful compounds such as polyethylene and p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Necrosis
Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. Necrosis is caused by factors external to the cell or tissue, such as infection, or trauma which result in the unregulated digestion of cell components. In contrast, apoptosis is a naturally occurring programmed and targeted cause of cellular death. While apoptosis often provides beneficial effects to the organism, necrosis is almost always detrimental and can be fatal. Cellular death due to necrosis does not follow the apoptotic signal transduction pathway, but rather various receptors are activated and result in the loss of cell membrane integrity and an uncontrolled release of products of cell death into the extracellular space. This initiates in the surrounding tissue an inflammatory response, which attracts leukocytes and nearby phagocytes which eliminate the dead cells by phagocytosis. However, microbial damaging substances released by leukocytes would crea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
