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Vinyldithiin
Vinyldithiins, more precisely named 3-vinyl-4''H''-1,2-dithiin and 2-vinyl-4''H''-1,3-dithiin, are organosulfur phytochemicals formed in the breakdown of allicin from crushed garlic (''Allium sativum''). Vinyldithiins are Diels-Alder dimers of thioacrolein, H2C=CHCH=S, formed in turn by decomposition of allicin. In garlic supplements, vinyldithiins are only found in garlic oil macerates that are made by incubation of crushed garlic in oil. __TOC__ Structure and occurrence When a garlic clove is crushed, the enzyme alliinase is released forming allicin from the cysteine sulfoxide alliin. Allicin breaks down into additional organosulfur compounds. In the presence of oil or organic solvents, among the compounds formed are the isomeric vinyldithiins and ajoene. As shown in the Scheme, allicin (1) decomposes into 2-propenesulfenic acid (2) and thioacrolein (3). Compound 2 reforms allicin while 3 gives Diels-Alder dimers 3-vinyl-4''H''-1,2-dithiin (4) and 2-vinyl-4''H''-1,3-dithiin (5) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Garlic
Garlic (''Allium sativum'') is a species of bulbous flowering plant in the genus '' Allium''. Its close relatives include the onion, shallot, leek, chive, Welsh onion and Chinese onion. It is native to South Asia, Central Asia and northeastern Iran and has long been used as a seasoning worldwide, with a history of several thousand years of human consumption and use. It was known to ancient Egyptians and has been used as both a food flavoring and a traditional medicine. China produces 76% of the world's supply of garlic. Etymology The word ''garlic'' derives from Old English, ''garlēac'', meaning ''gar'' (spear) and leek, as a 'spear-shaped leek'. Description ''Allium sativum'' is a perennial flowering plant growing from a bulb. It has a tall, erect flowering stem that grows up to . The leaf blade is flat, linear, solid, and approximately wide, with an acute apex. The plant may produce pink to purple flowers from July to September in the Northern Hemisphere. The bulb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organosulfur
Organosulfur compounds are organic compounds that contain sulfur. They are often associated with foul odors, but many of the sweetest compounds known are organosulfur derivatives, e.g., saccharin. Nature abounds with organosulfur compounds—sulfur is vital for life. Of the 20 common amino acids, two (cysteine and methionine) are organosulfur compounds, and the antibiotics penicillin and sulfa drugs both contain sulfur. While sulfur-containing antibiotics save many lives, sulfur mustard is a deadly chemical warfare agent. Fossil fuels, coal, petroleum, and natural gas, which are derived from ancient organisms, necessarily contain organosulfur compounds, the removal of which is a major focus of oil refineries. Sulfur shares the chalcogen group with oxygen, selenium, and tellurium, and it is expected that organosulfur compounds have similarities with carbon–oxygen, carbon–selenium, and carbon–tellurium compounds. A classical chemical test for the detection of sulfur compounds ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 membranes. When chemically isolated, it is a yellowish crystalline solid. Cholesterol also serves as a precursor for the biosynthesis of steroid hormones, bile acid and vitamin D. Cholesterol is the principal sterol synthesized by all animals. In vertebrates, hepatic cells typically produce the greatest amounts. It is absent among prokaryotes (bacteria and archaea), although there are some exceptions, such as '' Mycoplasma'', which require cholesterol for growth. François Poulletier de la Salle first identified cholesterol in solid form in gallstones in 1769. However, it was not until 1815 that chemist Michel Eugène Chevreul named the compound "cholesterine". Etymology The word "cholesterol" comes from the Ancient Greek ''chole- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 such infections. They may either kill or inhibit the growth of bacteria. A limited number of antibiotics also possess antiprotozoal activity. Antibiotics are not effective against viruses such as the common cold or influenza; drugs which inhibit viruses are termed antiviral drugs or antivirals rather than antibiotics. Sometimes, the term ''antibiotic''—literally "opposing life", from the Greek roots ἀντι ''anti'', "against" and βίος ''bios'', "life"—is broadly used to refer to any substance used against microbes, but in the usual medical usage, antibiotics (such as penicillin) are those produced naturally (by one microorganism fighting another), whereas non-antibiotic antibacterials (such as sulfonamides and antise ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antithrombotic
An antithrombotic agent is a drug that reduces the formation of blood clots (thrombi).http://cancerweb.ncl.ac.uk/cgi-bin/omd?antithrombotic Antithrombotics can be used therapeutically for prevention ( primary prevention, secondary prevention) or treatment of a dangerous blood clot (acute thrombus). In the U.S., the American College of Chest Physicians publishes clinical guidelines for clinicians for the use of these drugs to treat and prevent a variety of diseases. Processes Different antithrombotics affect different blood clotting processes: * Antiplatelet drugs limit the migration or aggregation of platelets. * Anticoagulants limit the ability of the blood to clot. * Thrombolytic drugs act to dissolve clots after they have formed. See also * Direct Xa inhibitor Direct factor Xa inhibitors (xabans) are anticoagulants (blood thinning drugs), used to both treat and prevent blood clots in veins, and prevent stroke and embolism in people with atrial fibrillation (AF). Medic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
N-Vinylpyrrolidone
''N''-Vinylpyrrolidone (NVP) is an organic compound consisting of a 5-membered lactam linked to a vinyl group. It is a colorless liquid although commercial samples can appear yellowish. It is produced industrially by vinylation of 2-pyrrolidone, i.e. the base-catalyzed reaction with acetylene. It is the precursor to polyvinylpyrrolidone (PVP), an important synthetic material. The NVP monomer is commonly used as a reactive diluent in ultraviolet and electron-beam curable polymers applied as inks, coatings or adhesives. Synthesis Starting from γ-Butyrolactone, 2-pyrrolidone is synthesized by treatment with ammonia. Subsequently, acetylene is used to introduce the vinyl group. See also * Methylpyrrolidone ''N''-Methyl-2-pyrrolidone (NMP) is an organic compound consisting of a 5-membered lactam. It is a colorless liquid, although impure samples can appear yellow. It is miscible with water and with most common organic solvents. It also belongs to ... (NMP) * 2-Pyrr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copolymer
In polymer chemistry, a copolymer is a polymer derived from more than one species of monomer. The polymerization of monomers into copolymers is called copolymerization. Copolymers obtained from the copolymerization of two monomer species are sometimes called ''bipolymers''. Those obtained from three and four monomers are called ''terpolymers'' and ''quaterpolymers'', respectively. Copolymers can be characterized by a variety of techniques such as NMR spectroscopy and size-exclusion chromatography to determine the molecular size, weight, properties, and composition of the material. Commercial copolymers include acrylonitrile butadiene styrene (ABS), styrene/butadiene co-polymer (SBR), nitrile rubber, styrene-acrylonitrile, styrene-isoprene-styrene (SIS) and ethylene-vinyl acetate, all of which are formed by chain-growth polymerization. Another production mechanism is step-growth polymerization, which is used to produce the nylon-12/6/66 copolymer of nylon 12, nylon 6 and nyl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Low-density Lipoprotein
Low-density lipoprotein (LDL) is one of the five major groups of lipoprotein that transport all fat molecules around the body in extracellular water. These groups, from least dense to most dense, are chylomicrons (aka ULDL by the overall density naming convention), very low-density lipoprotein (VLDL), intermediate-density lipoprotein (IDL), low-density lipoprotein (LDL) and high-density lipoprotein (HDL). LDL delivers fat molecules to cells. LDL is involved in atherosclerosis, a process in which it is oxidized within the walls of arteries. Overview Lipoproteins transfer lipids (fats) around the body in the extracellular fluid, making fats available to body cells for receptor-mediated endocytosis. Lipoproteins are complex particles composed of multiple proteins, typically 80–100 proteins per particle (organized by a single apolipoprotein B for LDL and the larger particles). A single LDL particle is about 220–275 angstroms in diameter, typically transporting 3,000 to 6,000 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydroperoxide
Hydroperoxides or peroxols are compounds containing the hydroperoxide functional group (ROOH). If the R is organic, the compounds are called organic hydroperoxides. Such compounds are a subset of organic peroxides, which have the formula ROOR. Organic hydroperoxides can either intentionally or unintentionally initiate explosive polymerisation in materials with unsaturated chemical bonds. Properties The O−O bond length in peroxides is about 1.45 Å, and the R−O−O angles (R = H, C) are about 110° (water-like). Characteristically, the C−O−O−H dihedral angles are about 120°. The O−O bond is relatively weak, with a bond dissociation energy of , less than half the strengths of C−C, C−H, and C−O bonds. Hydroperoxides are typically more volatile than the corresponding alcohols: * ''tert''-BuOOH (b.p. 36°C) vs ''tert''-BuOH (b.p. 82-83°C) * CH3OOH (b.p. 46°C) vs CH3OH (b.p. 65°C * cumene hydroperoxide (b.p. 153°C) vs cumyl alcohol (b.p. 202°C) Mis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lipid
Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include storing energy, signaling, and acting as structural components of cell membranes. Lipids have applications in the cosmetic and food industries, and in nanotechnology. Lipids may be broadly defined as hydrophobic or amphiphilic small molecules; the amphiphilic nature of some lipids allows them to form structures such as vesicles, multilamellar/unilamellar liposomes, or membranes in an aqueous environment. Biological lipids originate entirely or in part from two distinct types of biochemical subunits or "building-blocks": ketoacyl and isoprene groups. Using this approach, lipids may be divided into eight categories: fatty acyls, glycerolipids, glycerophospholipids, sphingolipids, saccharolipids, and polyketides (derived from cond ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cancer
Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal bleeding, prolonged cough, unexplained weight loss, and a change in bowel movements. While these symptoms may indicate cancer, they can also have other causes. Over 100 types of cancers affect humans. Tobacco use is the cause of about 22% of cancer deaths. Another 10% are due to obesity, poor diet, lack of physical activity or excessive drinking of alcohol. Other factors include certain infections, exposure to ionizing radiation, and environmental pollutants. In the developing world, 15% of cancers are due to infections such as ''Helicobacter pylori'', hepatitis B, hepatitis C, human papillomavirus infection, Epstein–Barr virus and human immunodeficiency virus (HIV). These factors act, at least partly, by changing the genes of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen Sulfide
Hydrogen sulfide is a chemical compound with the formula . It is a colorless chalcogen-hydride gas, and is poisonous, corrosive, and flammable, with trace amounts in ambient atmosphere having a characteristic foul odor of rotten eggs. The underground mine gas term for foul-smelling hydrogen sulfide-rich gas mixtures is ''stinkdamp''. Swedish chemist Carl Wilhelm Scheele is credited with having discovered the chemical composition of purified hydrogen sulfide in 1777. The British English spelling of this compound is hydrogen sulphide, a spelling no longer recommended by the Royal Society of Chemistry or the International Union of Pure and Applied Chemistry. Hydrogen sulfide is toxic to humans and most other animals by inhibiting cellular respiration in a manner similar to hydrogen cyanide. When it is inhaled or it or its salts are ingested in high amounts, damage to organs occurs rapidly with symptoms ranging from breathing difficulties to convulsions and death. Despite this, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
