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Debromoaplysiatoxin
Debromoaplysiatoxin is a toxic agent produced by the blue-green alga ''Lyngbya majuscula''. This alga lives in marine waters and causes seaweed dermatitis. Furthermore, it is a tumor promoter which has an anti-proliferative activity against various cancer cell lines in mice. History The first reported case of seaweed dermatitis was from 1958 in Hawaii on Oahu island. About 125 people who had been swimming in the sea get suffered from symptoms like itching, burning, blisters, rash and desquamation. The causative substance of this seaweed dermatitis was not known till 1968 when people in Okinawa, Japan, suffered from the same symptoms as the people in Hawaii. After researchers took samples in 1973 from ''Lyngbya majuscula'' they found out that this was the causative agent of the dermatitis. In 1980 there was a new outbreak of seaweed dermatitis on Oahu island Hawaii. Samples of ''L. majuscula'' revealed that this blue-green alga contained a mixture of aplysiatoxin, debromoaplysiat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aplysiatoxin
Aplysiatoxin is a cyanotoxin produced by certain cyanobacteria species. It is used as a defensive secretion to protect these cyanobacteria from predation by fish, being a potent irritant and carcinogen, by acting as a powerful activator of protein kinase C. While this action has a tumour-promoting effect, protein kinase C activation can be medically beneficial for some other applications, and synthetic analogues of aplysiatoxin have been researched for anti-cancer effects.Yanagita RC, Kamachi H, Tanaka K, Murakami A, Nakagawa Y, Tokuda H, Nagai H, Irie K. Role of the phenolic hydroxyl group in the biological activities of simplified analogue of aplysiatoxin with antiproliferative activity. ''Bioorganic & Medicinal Chemistry Letters''. 2010 Oct 15;20(20):6064-6. See also * Debromoaplysiatoxin Debromoaplysiatoxin is a toxic agent produced by the blue-green alga ''Lyngbya majuscula''. This alga lives in marine waters and causes seaweed dermatitis. Furthermore, it is a tumor promo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lyngbya Majuscula
''Lyngbya majuscula'' is a species of filamentous cyanobacteria in the genus '' Lyngbya''. It is named after the Dane Hans Christian Lyngbye. As a result of recent genetic analyses, several new genera were erected from the genus ''Lyngbya'': ''e.g.'', '' Moorea'', '' Limnoraphis'', '' Okeania'', '' Microseira'', and '' Dapis''. Almost 300 different secondary metabolites have been isolated from specimens identified as ''L. majuscula''. However, most of these studies lack a molecular identification of the samples. Several specimens identified as ''L. majuscula'' and collected in marine tropical regions are now classified as members of the genera ''Okeania'' and ''Moorea''. Antillatoxin Antillatoxin (ATX) is a potent lipopeptide neurotoxin produced by the marine cyanobacterium ''Lyngbya majuscula''. ATX activates voltage-gated sodium channels, which can cause cell depolarisation, NMDA-receptor overactivity, excess calcium influx ... and Kalkitoxin have been reported to be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hemiketal
A hemiacetal or a hemiketal has the general formula R1R2C(OH)OR, where R1 or R2 is hydrogen or an organic substituent. They generally result from the addition of an alcohol to an aldehyde or a ketone, although the latter are sometimes called hemiketals. Most sugars are hemiacetals. Nomenclature According to the IUPAC definition, in R1R2C(OH)OR R1 and R2 may or may not be a hydrogen. In a hemiketal, neither R-group can be a hydrogen. Hemiketals are regarded as hemiacetals where none of the R-groups are H, and are therefore a subclass of the hemiacetals. The Greek prefix ''hèmi'' means half, refers to the fact that a single alcohol has been added to the carbonyl group, in contrast to acetals or ketals, which are formed when a second alkoxy group has been added to the structure. Cyclic hemiacetals and hemiketals are sometimes called lactols.IUPAC Gold Boolactols/ref> They often form readily, especially when they are 5- and 6-membered rings. In this case an intramolecular OH group r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2,3-Dichloro-5,6-dicyano-1,4-benzoquinone
2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (or DDQ) is the chemical reagent with formula C6Cl2(CN)2O2. This oxidant is useful for the dehydrogenation of alcohols, phenols, and steroid ketones. DDQ decomposes in water, but is stable in aqueous mineral acid. Preparation Synthesis of DDQ involves cyanation of chloranil. J. Thiele and F. Günther first reported a 6-step preparation in 1906. The substance did not receive interest until its potential as a dehydrogenation agent was discovered. A single-step chlorination from 2,3-dicyanohydroquinone was reported in 1965. Reactions The reagent removes pairs of H atoms from organic molecules. The stoichiometry of its action is illustrated by the conversion of tetralin to naphthalene: :2 C6Cl2(CN)2O2 + C10H12 → 2 C6Cl2(CN)2(OH)2 + C10H8 The resulting hydroquinone is poorly soluble in typical reaction solvents (dioxane, benzene, alkanes), which facilitates workup. Solutions of DDQ in benzene are red, due to the formation of a charge- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbonyldiimidazole
1,1'-Carbonyldiimidazole (CDI) is an organic compound with the molecular formula (C3H3N2)2CO. It is a white crystalline solid. It is often used for the coupling of amino acids for peptide synthesis and as a reagent in organic synthesis. Preparation CDI can be prepared straightforwardly by the reaction of phosgene with four equivalents of imidazole under anhydrous conditions. Removal of the side product, imidazolium chloride, and solvent results in the crystalline product in ~90% yield. :4 C3H4N2 + C(O)Cl2 → (C3H3N2)2CO + 2 3H3N2H2l In this conversion, the imidazole serves both as the nucleophile and the base. An alternative precursor 1-(trimethylsilyl)imidazole requires more preparative effort with the advantage that the coproduct trimethylsilyl chloride is volatile. CDI hydrolyzes readily to give back imidazole: :(C3H3N2)2CO + H2O → 2 C3H4N2 + CO2 The purity of CDI can be determined by the amount of CO2 that is formed upon hydrolysis. Use in synthesis CD ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Chlorite
Sodium chlorite (NaClO2) is a chemical compound used in the manufacturing of paper and as a disinfectant. Use The main application of sodium chlorite is the generation of chlorine dioxide for bleaching and stripping of textiles, pulp, and paper. It is also used for disinfection of municipal water treatment plants after conversion to chlorine dioxide. An advantage in this application, as compared to the more commonly used chlorine, is that trihalomethanes (such as chloroform) are not produced from organic contaminants. Chlorine dioxide generated from sodium chlorite is approved by FDA under some conditions for disinfecting water used to wash fruits, vegetables, and poultry. Sodium chlorite, NaClO2, sometimes in combination with zinc chloride, also finds application as a component in therapeutic rinses, mouthwashes, toothpastes and gels, mouth sprays, as preservative in eye drops, and in contact lens cleaning solution under the trade name Purite. It is also used for sanitizi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
N-Chlorosuccinimide
''N''-Chlorosuccinimide is the organic compound with the formula C2H4(CO)2NCl. A white solid, it is used for chlorinations. It is also used as a mild oxidant. NCS is related to succinimide, but with NCl in place of NH. The N–Cl bond is highly reactive, and NCS functions as a source of "Cl+". Related reagents * ''N''-Iodosuccinimide (NIS), the iodine analog of ''N''-chlorosuccinimide. * ''N''-bromosuccinimide (NBS), the bromine Bromine is a chemical element with the symbol Br and atomic number 35. It is the third-lightest element in group 17 of the periodic table (halogens) and is a volatile red-brown liquid at room temperature that evaporates readily to form a simil ... analog of ''N''-chlorosuccinimide. * Other ''N''-chloro compounds that are commercially available include chloramine-T, trichloroisocyanuric acid ((OCNCl)3), 1,3-dichloro-5,5-dimethylhydantoin. Further reading * References External links''N''-ChlorosuccinimideanN-IodosuccinimideaOrganic Chemi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
N,N'-Dicyclohexylcarbodiimide
''N'',''N''′-Dicyclohexylcarbodiimide (DCC or DCCD) is an organic compound with the chemical formula (C6H11N)2C. It is a waxy white solid with a sweet odor. Its primary use is to couple amino acids during artificial peptide synthesis. The low melting point of this material allows it to be melted for easy handling. It is highly soluble in dichloromethane, tetrahydrofuran, acetonitrile and dimethylformamide, but insoluble in water. Structure and spectroscopy The C−N=C=N−C core of carbodiimides (N=C=N) is linear, being related to the structure of allene. The molecule has idealized C2 symmetry. The N=C=N moiety gives characteristic IR spectroscopic signature at 2117 cm−1. The 15N NMR spectrum shows a characteristic shift of 275 ppm upfield of nitric acid and the 13C NMR spectrum features a peak at about 139 ppm downfield from TMS. Preparation DCC is produced by the decarboxylation of cyclohexyl isocyanate using phosphine oxides as a catalyst: :2 C6H11N ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blaise Reaction
The Blaise reaction is an organic reaction that forms a β-ketoester from the reaction of zinc metal with a α-bromoester and a nitrile. The reaction was first reported by Edmond Blaise (1872–1939) in 1901. The final intermediate is a metaloimine, which is then hydrolyzed to give the desired β-ketoester. Bulky aliphatic esters tend to give higher yields. Steven Hannick and Yoshito Kishi have developed an improved procedure. It has been noted that free hydroxyl groups can be tolerated in the course of this reaction, which is surprising for reactions of organometallic halides. Mechanism The mechanism of the Blaise reaction involves the formation of an organozinc complex with the bromine alpha to the ester carbonyl. This makes the alpha carbon nucleophilic, allowing it to attack the electrophilic carbon of the nitrile. The negative nitrile nitrogen resulting from this attack complexes with the zinc monobromide cation. The β-enamino ester (tautomer of the imine intermediate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Esterification
In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides are fatty acid esters of glycerol; they are important in biology, being one of the main classes of lipids and comprising the bulk of animal fats and vegetable oils. Esters typically have a pleasant smell; those of low molecular weight are commonly used as fragrances and are found in essential oils and pheromones. They perform as high-grade solvents for a broad array of plastics, plasticizers, resins, and lacquers, and are one of the largest classes of synthetic lubricants on the commercial market. Polyesters are important plastics, with monomers linked by ester moieties. Phosphoesters form the backbone of DNA molecules. Nitrate esters, such as nitroglycerin, are known for their explosive properties. '' Nomenclature ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
